Earth and Life Science

EARTH AND
LIFE SCIENCE
Mr. Bern E. Alvis

0921-757-7175
Southwestern College of Maritime, Business and Technology, Inc.
Quezon Drive, Calero, Calapan City, Oriental Mindoro
www.scmbt.edu.ph / slmifnav.official@gmail.com / slmifnav@yahoo.com.ph
SUBJECT: Earth and Life Sciences DATE:

MODULE #: 1 TEACHER: Mr. Bern Evora Alvis
I. TOPIC: Universe and the Solar System

 Origin of the Universe
 Structure, Composition, and Age of the Universe
 Evidence of the Big Bang
 Origin of the Solar System
 Earth as a System & its Subsystem
 Earth’s Internal Structure
II. LEARNING COMPETENCY
The learner should be able to:

 Recognize the uniqueness of Earth, being the only planet in the solar system with
properties necessary to support life. (S11/12ES-Ia-e- 3)
 Explain that the Earth consists of four subsystems, across whose boundaries matter and
energy flow. (S11/12ES-Ia-e- 4)
 Identify common rock-forming minerals using their physical and chemical properties.
(S11/12ES-Ia-9)
III. TARGET LEARNING OUTCOMES
 At the end of the lesson, the student is expected to:

 State the different hypothesis that explain the origin of the universe and the solar system.
 Explain the Big Bang Theory and evidence supporting the theory.
 Describe the Earth’s interior (in terms of crust, mantle, and core)
 Compare the Earth’s layers.
 Define the concept of a system.
 Recognize the Earth as a system composed of subsystems.
 Classify and describe the three basic rock types.
IV. MATERIALS NEEDED AND REFERENCES
To accomplish exercises and activities, you need the following: black pen, pencil and/or other
writing materials and other available references.
REFERENCES Raymond A. Baltazar, Ceazar Ryan U. Cuarto, Jigger P. Leonor, Ph.D.,

2016, Conceptual Science and Beyond Earth and Life Science (A Worktext
for Senior High School), Brilliant Creations Publishing, Inc.: Bonanza Plaza
2, Block 1, Lot 6, Hilltop Subdivision Greater Lagro, Novaliches, Quezon
City, pp. 2-11 & 18-19
Gloria G. Salandanan, Ph.D., Ruben E. Faltado III, Ph.D., Merle B. Lopez,

Ed.D., 2016, Earth and Life Sciences For Senior High School (Core
Subject), LORIMAR PUBLISHING, INC.: 776 Aurora Blvd.,cor. Boston
Street, Cubao, Quezon City, Metro Manila, pp. 4-6, 29-33, & 55-57
V. GEAR UP YOUR MIND

This chapter answers the question: How did our world come to be? It primarily discusses the
beginning of the universe as well as the planets in the solar system. This will provide a glimpse of how
all things have started as postulated through the various studies and discoveries in our universe. As
stewards of nature, knowing the origin of our planet Earth may help us understand how to take care of
it.
This chapter will focus on the different theories explaining the origin of the universe and the solar
system, as well as the origin and the structure of Earth.
1.1 How did the Universe Come to Be?
Rigveda
 Can be found the earliest musings about the origin of the universe
 an ancient Indian collection of Vedic Sanskrit hymns along with associated
commentaries on liturgy, ritual and mystical exegesis
 one of the four sacred canonical texts (śruti) of Hinduism known as the Vedas
Hymn of Creation of Rigveda

 reveals that ancient Indians believed that the universe had an
origin
Ancient Greeks
 the cosmos was timeless and infinite
 came the idea of the universe having a center PHILOLAUS
Philolaus (470-385 B.C.)

 Central fire is the center
 Other celestial objects (sun, moon, & other planets) revolved
uniformly
ARISTARCHUS
Aristarchus
 Central fire was actually the Sun
 1st to propose a heliocentric model
Aristotle (384-322 B.C.) ARISTOTLE

 One of the greatest minds in Greek Classical Antiquity
 Propose the geocentric model
HELIOCENTRIC MODEL GEOCENTRIC MODEL
PTOLEMY
Claudius Ptolemy
 Greco-Egyptian mathematician, geographer, astrologer, and
astronomer
 Elaborated the geocentric model
 Ptolemaic model
Albert Einstein
 the universe was a finite and static closed four-dimensional
sphere
 lead to the dev’t of the Big Bang
1.1.1 Structure, Composition, and Age

EINSTEIN
 4.6% baryonic matter (“ordinary” matter consisting of protons, electrons, and neutrons:
atoms, planets, stars, galaxies, nebulae, and other bodies),
 24% cold dark matter (matter that has gravity but does not emit light)
 71.4% dark energy (a source of anti-gravity).
Most Abundant Elements
 hydrogen
 helium
 lithium
Galaxy
 cluster of billions of stars and clusters of galaxies form superclusters.
Recent data
 13.7 billion years old.
 diameter of the universe is possibly infinite but should be at least 91 billion light-years
(1 light-year = 9.4607 × 1012 km).
 density is 4.5 x 10-31 g/cm3.
Now, let’s move on the different theories in the origin of the universe.
1.1.2 Origin of the Universe
 Non-Scientific Thought
Ancient Egyptians
- believed in many gods and myths which narrate that the world arose from an
infinite sea at the first rising of the sun
Kuba
- people of Central Africa tell the story of a creator god Mbombo (or Bumba) who,
alone in a dark and water-covered Earth, felt an intense stomach pain and then
vomited the stars, sun, and moon.
India
- there is the narrative that gods sacrificed Purusha, the primal man whose head,
feet, eyes, and mind became the sky, earth, sun, and moon respectively.
Judaism, Christianity, and Islam
- claim that a supreme being created the universe, including man and other living
organisms.
Unlike hypotheses in the sciences, religious beliefs cannot be subjected to tests using the scientific
method. For this reason, they cannot be considered valid topic of scientific inquiry.
 Creationist Theory- God, the Supreme Being created the whole universe. The proof can be
read in the Holy Bible stipulating that God created the heavens and the earth including the
man.
 Oscillating Universe Theory- this theory was proposed by a Russian-born US cosmologist
George Gamow who helped explain the Big Bang Theory. He said that the expansion will stop,
then it collapses until it returns to its original form then another Big bang will occur. This theory
is a never-ending cycle known as Oscillating Universe.
 Steady-State Theory- this theory states that the universe has always been the same since the
beginning and will remain that way forever. The now discredited steady state model of the
universe was proposed in 1948 by Bondi and Gould and by Hoyle.
 Big Bang Theory- the most accepted theory today. According to this theory developed by
various scientist and philosophers, about 13.7 billion years ago, matter and energy were
compressed and condensed in a hot tiny dense mass. But due to random fluctuations, this tiny
dense and compact point exploded tremendously. This explosion is termed as the Big Bang
Theory.
Misconception: the “bang” was an explosion, like with the fire and sound, and well, kind
of like a bomb but it was probably more like a balloon being blown up. This means that it was
just an expansion.
- The Big Bang Theory has withstood the tests for expansion: 1) the redshift 2) abundance
of light elements, and 3) the uniformly pervasive cosmic microwave background radiation-
the remnant heat from the bang.
1.1.3 Evidence of the Big Bang Theory

 Occurrence of Red Shift- it was proposed by Edwin Hubble. It is stated that galaxies are
moving away from each other. He observed that spectral lines of starlight made to pass
through a prism are shifted toward the red part of the electromagnetic spectrum.
 Cosmic Microwave Background- is an Electromagnetic radiation left over from an early
stage of the universe in the Big Bang cosmology. It was accidentally discovered in1964 by
Arno Penzias and Robert Woodrow Wilson.
 Abundance of Light Elements- the theory predicts that the universe is composed of 75 %
hydrogen and 25 % helium by mass.
Now, that we are already know how the universe form, let us now proceed on how did the Solar
System form.
1.2 Overview about Solar System

 The solar system is in the Milky Way galaxy-- a huge disc- and spiral-shaped aggregation
of about at least 100 billion stars and other bodies.
 Its spiral arms rotate around a globular cluster or bulge of many, many stars, at the center
of which lies a supermassive black hole.
 This galaxy is about 100 million light years across (1 light year = 9.4607 × 1012 km).
 The solar system revolves around the galactic center once in about 240 million years.
 The Milky Way is part of the so-called Local Group of galaxies, which in turn is part of the
Virgo supercluster of galaxies.
 Based on the assumption that they are remnants of the materials from which they were
formed, radioactive dating of meteorites, suggests that the Earth and solar system are 4.6
billion years old. On the assumption that they are remnants of the materials from which
they were formed.
1.2.1 How did the Solar System Form?

Recent advances in science and technology aided us in explaining the origin of the Earth and other
planets. Information derived from optical telescopes, space probes, computer power, and better
techniques for detecting planets serve as considerable pieces of evidence in testing earlier theories.
Some of these important pieces of information were:
1. Mass distribution- the mass of the system is not evenly distributed. Most of the mass is
concentrated in the sun.
2. Angular momentum distribution- like mass distribution, the angular momentum (tendency to
rotate) is concentrated more among the planets in comparison to the sun.
3. Shape and alignment of orbits- the planets move in nearly circular orbits that nearly align
with the equator of the sun in the same direction.
4. Chemical compositions- the planets and the sun have similar chemical compositions,
although in varying proportions. Planets in the solar system are subdivided into two groups: the
small, heavy, and non-volatile planets; and the large, light, and volatile planets.
From these scientific data, various models had been created to explain the origin of the Earth.
1.2.2 Origin of the Solar System

Many theories have been proposed since about four centuries ago. Each has weaknesses in
explaining all characteristics of the solar system. A few are discussed below.
 Nebular Hypothesis- is proposed by Emanuel Swedenborg, Immanuel Kant, and Pierre-
Simon Laplace in 1700s. This states that a rotating gaseous cloud that cools and contracts in
the middle to form the sun and the rest into a disc that become the planets.
 Encounter Hypothesis- is proposed by Chamberlin and Moulton. According to this theory, the
planets formed from debris torn off the Sun by a close encounter with another star. That our
planets, moons, and sun all spun off from a collision between stars.
 Protoplanet Hypothesis- developed by Carl von Weizsacker and Gerard Kuiper. According to
this theory Solar System begins to form, as a rotating cloud, or nebula collapses. But
instabilities develop in the nebula causing dust particles to pull together. Then the dust
particles merge into billions of planetesimals then collide and form protoplanets. At the center
of the nebular disk the protosun increases in mass and becomes a star by the process of
hydrogen fusion.
1.3 Earth: A Habitable Planet

For 4.6 billion years, Earth’s structure has undergone– and is continuously undergoing – grand
changes. In fact, in its primitive form, Earth did not look like how it looks today: a beautiful blue marble.
Between 3.8 to 4 million years ago, Earth experienced heavy bombardment, making Earth a dangerous
place for any living thing. After the bombardment period, land and bodies of water have begun to form.
In addition, gaseous materials formed the atmosphere that was finally able to support life on the
surface.
1.3.1 Earth as a System and its Subsystems

Scientists view Earth as a system that is composed of different parts that are independent from
one another but are interrelated and interact with one another. These parts are known to be the
components of Earth but can viewed as subsystems of the Earth. These subsystems are the
geosphere, the hydrosphere, the atmosphere, the cryosphere, and the biosphere. Cryosphere, the
layer pertaining to ice, is usually considered as part of the hydrosphere, thus limiting the subsystems
into four.
 Geosphere- comprises the solid layer of Earth, that is, rocks and minerals that provide
nutrients to plants and animals.
 Hydrosphere- comprises the 70% of the Earth’s surface that is water.
 Atmosphere- comprises the air that we breathe. This is made up of many layers that protect
us from the outer space.
 Biosphere- pertains to every life form, which includes us humans.
Each subsystem may be independent from one another but are interconnected through a
biogeochemical cycle.
1.4 The Internal Structure of the Earth

Before we proceed to knowing what the Earth really looks like, let us test your prior knowledge
about the internal structure of the Earth. Look at Pre-Activity 1.1 the next pages of this module and
answer what is ask.
After having finished Activity 1.3, let us proceed with the composition of the Earth.
Earth consists of three concentric layers: —the crust, mantle, and core. Based on physical
properties, Earth is also divided into layers. Think of the layers of the Earth like the layers of a cake.
Layers of the Earth

a. Crust
The Crust is the thin, outermost layer of the Earth. It is composed of a great variety of igneous,
metamorphic, and sedimentary rocks. The rocks found in the crust consist mostly of lighter
elements such as silicon, potassium, and sodium. The density of these rocks is about three times
that of water. Difference in chemical composition resulted into two types of crust: oceanic and
continental crust.
2 Types of Crust
Oceanic crust- is 5 km to 10 km thick, is cc
Continental crust- which is 30 km to 50 km thick, is mostly composed of less dense
rocks than the oceanic crust. Some of these less dense rocks, such as granite, are
common in the continental crust, but rare in the oceanic crust.
It is said that the crust is divided into two layers: sial and sima.
2 Layers of Crust
Sial- the uppermost layer whose name is derived from the first two letters of the two
most abundant elements found in it, silicon (Si) and aluminum (Al).
Sima- the lower crust made up mostly of silicon (Si) and magnesium (Mg).
 MOHOROVICIC DISCONTINUITY- “MOHO” is the boundary separating the crust and the
mantle
b. Mantle
The mantle middle layer of the earth between the crust and the core. Earth’s mantle is a 2,885
km thick shell of rock surrounding the planet’s outer core, lying directly beneath the thin crust,
roughly between 30 and 2,900 km below the surface. It occupies about 84 % of Earth’s volume.
The term “mantle” is also applied to the rock shell surrounding the core of the other planets. In the
solar system, the Earth’s mantle is the only one that is continually active.
The mantle differs from crust in terms of mechanical characteristics & chemical compositions.
Mantle rocks consist of olivine’s, diff. pyroxenes, and other mafic minerals. Mantle rocks also
possess a high portion of iron and magnesium and a smaller portion of silicon and aluminum than
the crust. The mantle temperature ranges between 1,000 °C at the upper boundary near the crust
– which extends from the crust to a depth of about 410 km– to over 4,000 °C at the lower boundary
near the outer core– which extends from about 660 km to about 2,700 km beneath the crust.
Between the upper and lower mantle is the transition zone where rocks undergo radical
transformation.
Mantle activity accounts for our planet’s changing geological landscape. It is caused by
convection currents which transfer hot, buoyant magma from the core to the lithosphere and
denser, cooler rocks to Earth’s interior through subduction.
c. Core
With a thickness of 1,216 km, the inner core of the Earth is mostly composed of solid iron and
nickel; surrounded by the liquid iron outer core with a thickness of 2,270 km. The core is believed
to have a maximum relative density of 13 and has a maximum temperature of 6,400ºC. The flowing
iron and nickel in the outer core resulted to the formation if the magnetic field that further protects
the Earth.
1.5 What Makes Up the Crust of the Earth?

The Earth’s crust is made of rock, which in turn are composed of minerals.
1.5.1 Rocks
Petrology is the study of rocks.
Rocks
 natural solid materials that make up the most of the Earth’s lithosphere
 found lying around the surface of the Earth and even beneath it
 Rocks that form a bigger mass are composed of tiny particles of minerals compressed
together due to pressure and temperature
 They can be composed of a single mineral or different minerals.
There are three types of rocks which can interchangeably transform from one type to another.
These are igneous, sedimentary, and metamorphic rocks.
1. Igneous rocks – rocks are formed from the solidification of lava when a volcano erupts. There
are two basic types—intrusive or plutonic igneous rocks, and extrusive or volcanic igneous
rocks. Magma does not always reach the surface of the Earth and sometimes gets trapped
beneath the ground.
2 Type of Igneous Rocks
1. Intrusive or plutonic igneous rocks- Cools below the earth’s surface (slowly!). Form
larger crystals and coarse- grained rocks
Ex: granite, diorite, gabbro, pegmatite, dunite and peridotite
2. Extrusive or volcanic igneous rocks- Cools at the earth’s surface (quickly!). Cools at the
earth’s surface (quickly!)
Ex: basalt, andesite, obsidian, pumice, rhyolite, scoria, and tuff
Igneous rocks can be classified according to their mode of occurrence, texture, mineralogy,
chemical composition, and the geometry of the igneous body.
Textures describes the physical appearance of the rock based on the size and arrangement of
its crystal components. Igneous rocks can be classified as follows.
a. Fine-grained igneous rocks- consist of very small crystals formed through rapid cooling
at the surface of the earth.
b. Coarse-grained igneous rocks- consist of large crystals and likely formed far below the
surface of the earth.
c. Porphyritic igneous rocks- consist of large crystals embedded on a group of smaller
crystals.
d. Glassy igneous rocks- formed when a molten rock is ejected by a volcano into the
atmosphere causing the lava to cool instantly.
2. Sedimentary Rocks- are rocks formed by the accumulation of sediments. There are three
basic types of sedimentary rocks: clastic, chemical, and organic.
a. Clastic sedimentary rocks- are composed of clasts, which are little pieces of broken rock
particles that have been joined together as a result if compaction and cementation.
Ex: breccia, conglomerate, sandstone, siltstone, and shale
b. Chemical sedimentary rocks- are formed as a result if repeated flooding and
evaporation. Usually, when water evaporated, it leaves a layer of dissolved minerals
behind.
Ex: rock salt, iron ore, chert, flint, some dolomites, and some limestones
c. Organic sedimentary rocks- form from the accumulation of plant or animal debris.
Ex: coal, some dolomites, and some limestones
3. Metamorphic Rocks- have been modified by heat, pressure, and chemical processes usually
while buried deep below the Earth’s surface. Exposure to these extreme conditions can alter
the mineralogy, texture, and chemical composition of the rocks. Metamorphic rocks can be
foliated or nonfoliated.
a. Foliated metamorphic rocks- have layered or banded appearance caused by exposure

of minerals to heat and pressure.
b. Nonfoliated metamorphic rocks- do not display layering or banding that are present in
foliated rocks.
1.5.2 Rock Cycle

The rock cycle summarizes the transformational processes that change rocks from one kind to
another. It shows the entire journey of rocks formed as they changed. These may take millions of years
NAME OF STUDENT: Earth and Life Sciences
SECTION: MODULE #: 1
VI. BOOST UP YOUR LEARNING
Activity 1.1: A Model of an Expanding Universe

I.Objective:
 To make a model of an expanding universe
II.Materials
 1 balloon (not red or black)
 marker pens (1 red, 1 black)
 1 tape measure
III. Procedure
1. Make a data table with 5 columns and 10 rows like the one shown below.
IV. Data and Observations:
Dots Distance from Distance from the dot Change of Factor by

the dot at the at the Center after distance from which
Center (cm) expansion (cm) center (cm) distances
change (cm)
(1) (2) (2-1) (2÷1)
A
B
C
D
E
F
G
H
I
J
Diameter of the balloon: _______
1. Blow the balloon with air until it is stretched tight and hold it closed.
2. Using a tape measure, measure its diameter.
3. Draw red dots on the surface of the balloon about two centimeters apart.
4. Locate a central dot and encircle it with a black marker.
5. Choose 10 dots- some far and some near the central dot. Label these dots A to J.
6. Measure the distances of dots A to J from the central dot. Record these distances in
column 2 of your data table.
7. Blow again your balloon. This time, measure the distance of dots A to J from the central
dot. Record the distances in column 3 of the data table.
8. Subtract the data in column 2 from the corresponding data in column 3. Record the
resulting data in column 4.
9. Divide the data in column 3 by the corresponding data in column 2. Record your answers
in column 5.
IV. Guide Questions:
1. What do blowing the balloon represent?
2. Compare the data in column 2 with the data in column 4. Explain your answer.
3. Compare the set of data in column 2 with the set of data in column 5. Explain your answer.
What conclusion can be drawn about the universe based on the activity.

I. TOPIC: Earth Materials and Processes

 Classification of Rocks
 Exogenic Processes
Weathering
Erosion
Mass Wasting
 Endogenic Processes

 Identify common rock-forming minerals using their physical and chemical properties.
(S11/12ES-Ia-9)
 Classify rocks into igneous, sedimentary, and metamorphic (S11/12ES-Ib-10)
 Explain how the products of weathering are carried away by erosion and deposited
elsewhere (S11/12ES-Ib-12)
At the end of the lesson, the student is expected to:

 Classify and identify the three types of rocks;
 Explain the rock cycle;
 Define weathering and distinguish between the two main types of weathering: and
 Identify the factors that affect the rate of weathering

City, pp. 18-22

Street, Cubao, Quezon City, Metro Manila, pp. 55-57 & 60-62
1.1 Rock Classifications
Petrology – study of rocks

Rocks
 Natural solid materials that make up the most of the Earth’s
lithosphere
 Found lying around the surface of the earth and even
beneath it
 Rocks that form a bigger mass are composed of tiny
particles of minerals
compressed due to pressure and temperature
 Composed of a single mineral or several different minerals
Three (3) Types of Rocks

 Igneous Rocks
 Sedimentary Rocks
 Metamorphic Rocks
A.Igneous Rocks
 Derived from the latin word ignis meaning “fire”
 Formed from the solidification of lava when a volcano erupts
Magma vs. Lava

Magma
 molten rock material beneath the surface.
Lava
 molten rock material extruded to the surface of the earth
through a volcanic or a fissure eruption
Two (2) Basic Types of Igneous Rocks
Intrusive or plutonic igneous rocks

 Cools below the earth’s surface (slowly!). Form
larger crystals and coarse- grained rocks
 This is because the longer time for cooling is, the
more the time for crystals of the same chemical
composition to group together.
Example: granite, diorite, gabbro, pegmatite, dunite, and peridotite
Extrusive or volcanic igneous rocks

 Cools at the earth’s surface (quickly!). Form small
crystals
 This is because, there is less time for crystals of
the same chemical composition to group together.
Example: basalt, andesite, obsidian, pumice, rhyolite,
scoria, and tuff
Types of Texture
Texture Description Example

a.Fine-grained igneous  Consist of very small
rocks crystals
 Formed at the surface of
the earth
 Fast rate of cooling
Rhyolite
b.Coarse-graned igneous  Consists of large crystals
rocks  Formed far below the
surface of the earth
 Slow rate of cooling
Granite
c.Porphyritic igneous  consist of large crystals
rocks embedded on a group of
smaller crystals.
 Two (2) rates of cooling
Andesite porphyry
d.Glassy igneous rocks  formed when a molten rock
is ejected by a volcano into
the atmosphere causing the
lava to cool instantly.
 Very fast rate of cooling
Obsidian
B. Sedimentary Rocks
From the root word sediments which means “remaining particles”
 rocks formed by the accumulation of sediments. There are three
basic types of sedimentary rocks: clastic, chemical, and organic
Three (3) Basic Types of Sedimentary

Rocks
1. Clastic Sedimentary Rocks
2. Chemical Sedimentary Rocks
3. Organic Sedimentary Rocks
Clastic Sedimentary Rocks

 Composed of clasts, which are little pieces of broken rock
particles that have been joined together because of
compaction and cementation
Examples: breccia, conglomerate, sandstone, siltstobe, and shale
Chemical Sedimentary Rocks

 are formed as a result if repeated flooding and
evaporation. Usually, when water evaporated, it leaves a
layer of dissolved minerals behind
Examples: rock salt, iron ore, chert, flint, some dolomites, and
some limestones
Organic Sedimentary Rocks

 form from the accumulation of plant or animal debris.
Examples: coal, some dolomites, and some limestones
C.Metamorphic Rocks
 Meta means “change”
 have been modified by heat, pressure, and chemical processes usually
while buried deep below the Earth’s surface. Exposure to these extreme
conditions can alter the mineralogy, texture, and chemical composition
of the rocks.
Two (2) Types of Metamorphic

Rocks
Foliated metamorphic rocks

 have layered or banded appearance caused by
exposure of minerals
Non-foliated metamorphic rocks
 do not display layering or banding that are present in foliated
rocks.
1.1.2 Rock Cycle
To conveniently discuss the When igneous rocks make

rock cycle let us begin with the their way to the surface, they
formation of igneous rocks. will be pick up, transported and
Igneous rocks are formed by deposited by any number of
solidification and cooling of erosional agents such as
molten materials. This running water, glaciers, wind
process called crystallization and waves. Due to these
may occur either beneath the agents, the rocks will turn into
earth’s surface or following sediments, which will be
volcanic eruption at the surface deposited, usually as
horizontal beds in the ocean
and will undergo lithification.
This process where rocks
experience cementation and
compaction of converting the
sediments into solid rock
(sedimentary rocks).
If the resulting sedimentary is buried deep within the earth or involved in the
dynamic of mountain building, it will be subjected to great heat and pressure.
The sedimentary rock will react to changing environment turn into the third
type, metamorphic rock. When metamorphic rock is subjected to still greater
heat and pressure, it will melt to create magma, which will eventually solidify
as igneous rock
Alternative Path….
The path shown in Figure 1 is only the basic cycle; this is not the only possible path. For
example, if the igneous rock did not reach the surface instead is subjected to heat and
pressure beneath, it will turn into a metamorphic rock. Metamorphic rocks may be
exposed to the surface and be subjected to the agents that will turn them into sediments
and eventually through lithifications turn them into sedimentary rocks. Sedimentary rocks
may be get buried and melt turning into magma which will turn into igneous rocks. Rocks
can transform from one form to another. When magma pours out on Earth's surface,
magma is called lava. Lava is the same liquid rock matter that you see coming out of
volcanoes.
2.1 What Factors Cause the Different Shapes and Structures of the Earth?
If you look at the Earth from a distance, it looks as if it does not have a uniform
appearance. The Earth has varying shapes, structures, and formations, which could be attributed
to the different processes that alter its face. These processes could be either exogenic, which
occurs externally at or near the Earth’s surface, or endogenic, which occurs internally below the
Earth’s surface.
Let us discuss first the exogenic processes!
2.1.1 Exogenic Processes
Exogenic processes are caused by exogenic factors, or agents supplying energy for
activities that are located at or near the Earth’s surface. Exogenic factors are usually driven by
gravitational and/or atmospheric forces. Processes that are caused by exogenic factors are
weathering, erosion, and mass wasting.
Before we proceed to knowing what weathering is, I will ask you something. Look at Pre-
Activity 1.1 in the next pages of this module and answer what is ask.
After having finished Pre-Activity 1.3, let’s proceed on the definition of Weathering.
Weathering
 Process of degradation or breaking down of rocks into smaller fragments known as
sediments.
 occurs when mechanical force is applied on rocks or through chemical reactions
happening on the surface or within the rocks
We have two types of weathering: the physical weathering and chemical weathering. Let
us discuss it one by one!
3 Types of Weathering
1. Physical Weathering- is also called mechanical weathering and it is caused by the
breaking apart of rocks without changing their chemical composition.
Ex: place a tablet on the table and break or crush it with its spoon and tearing a
paper
This shows a physical weathering as the tablet broken down into pieces without
changing its chemical composition.
The following are some examples that illustrate physical weathering.
Frost heaving and wedging- this occurs when water seeps into the rocks or occupies
spaces in between rocks and freezes, acting like a wedge. When water gets inside the
joints, alternate freezing and thawing episodes pry the rock apart.
Plant roots- huge trees that produce large roots anchor themselves on rocks and force
their way into them.
Burrowing animals- some animals create their homes by making holes on the rocks.
Abrasion- is wearing away of rocks by repeated collision or impacts. Rocks in the rivers,
seas, valleys, mountains, or deserts, degrade or disintegrate due to friction or repeated
collisions or impacts.
Temperature changes- sudden changes in temperature weaken the integral structure of
rocks, resulting to weathering.
2. Chemical Weathering- involves the chemical decomposition of rocks due to the chemical
reaction of minerals within rocks & the environment. It occurs when the internal structure of
a rock is changed by the removal or addition of elements.
Ex: dissolving an antacid in water or burning a piece of paper
This shows a chemical weathering as the antacid dissolve in water that cause changing its
chemical composition
Some agents of chemical weathering are as follows:
Water- it dissolves the soluble minerals present in rocks. This process is known as
hydrolysis.
Oxygen- it facilitates the oxidation process in the presence of water in some metallic
minerals, such as pyrite.
Living organisms- organisms, such as lichens, produce weak acids that slowly corrode
the rocks.
Acids- Carbon acid (H2CO3) is formed when carbon dioxide (CO2) present in the
atmosphere reacts with water. It easily decomposes limestones and marbles. Acid rain is
formed from non-metallic oxides (Cox, NOx, & SOx). These oxides are formed from the
burning of coal and natural activities that react with rainwater to form acids in the
atmosphere. Abundance of these acids results in observable damages to structure,
buildings, plants, and vegetation as well.
Erosion
Erosion happens when fragments of rocks move from one place to another. It is called
erosion if rock fragments are moved by various agents, such as air, water, and ice.
Mass Wasting
Mass wasting is the movement of large fragment of rocks down the slope due to gravity.
Ex: landslide, mudslide, slumps, and debris flow
Landslide- Masses of rocks or sediment slide downslope along surfaces

Rockslides- Rapid flow of rock mass along flat inclined surface
Slump- Due to slow moderate sliding of sediment or rock mass along a curved surface
Creep- Extra slow movement of rocks
Mudflow- Very slow to rapid movement of fine-grained sediment and rock particles up to
30% water.
Pre-Activity 1.1
Answer the following question:
1. Can you name any natural cause or process that could possibly break the rock into
smaller pieces?
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2. If the early Earth’s crust was mainly composed of rocks, why do we have layers of soil
on the surface now? Where did these soils came from?”
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Activity 1.1
Where Do I Belong?
I. Objective:
 Classify rocks into igneous, sedimentary, and metamorphic
II. Materials:
 Activity sheet/ module
 Pen
III. Procedure:
Classify the following rocks in the first box as to Igneous, Sedimentary and Metamorphic.
granite marble basalt gypsum
conglomerate calcite slate schist
pumice sandstone diorite quartzite
halite andesite limestone
Igneous Rocks Sedimentary Rocks Metamorphic Rocks


I. TOPIC: Earth Materials and Processes

 Heat in the Interior of the Earth
 Internal temperature of the Earth
 Magma Formation
 Metamorphism
 Different Igneous Rock Types

 Describe where the Earth’s internal heat comes from. (S11/12ES-Ib-14)
 Describe how magma is formed (magmatism) (S11/12ES-Ic-15)
 Describe the physical and chemical changes in rocks due to changes in pressure
and temperature (metamorphism)
 Compare and contrast the formation of the different types of igneous rocks
(S11/12ES-Ic-18)

 Know the sources and significance of the Earth's internal heat.
 Understand and explain the requirements for magma generation.
 Discuss metamorphism.
 Discuss the relationship of the different igneous rock types and the environment of
formation

REFERENCES Gloria G. Salandanan, Ph.D., Ruben E. Faltado III, Ph.D., Merle B. Lopez,
Street, Cubao, Quezon City, Metro Manila, pp. 66
Earth and Life Science Teachers Guide, pp. 91-95 & p. 101
3.1 Heat in the Interior of the Earth

We have two categories of the internal heat sources of the Earth: primordial heat and
radioactive heat.
a. Primordial heat: heat from accretion and bombardment of the Earth during the early
stages of formation. If you hit a hammer on hard surface several times, the metal in the
hammer will heat up (kinetic energy is transformed into heat energy).
b. Radioactive heat (the heat generated by long-term radioactive decay): its main sources
are the four long-lived isotopes (large half-life), namely K40, Th232, U235 and U238 that
made a continuing heat source over geologic time.
3.2 The estimated internal temperature of the Earth
a. The mantle and asthenosphere are considerably hotter than the lithosphere, and the core
is much hotter than the mantle.
b. Core-mantle boundary: 3,700°C
c. Inner-core – outer-core boundary: 6,300°C±800°C
d. Earth’s center: 6,400°C±600°C
Temperature increases with depth, yet the mantle and inner core remain solid!
3.3 Magma Formation

This are the special conditions required for the formation of magma:
a. Crust and mantle are almost entirely solid, indicating that magma only forms in special
places where pre-existing solid rocks undergo melting.
b. Melting due to decrease in pressure (decompression melting): The decrease in pressure

affecting a hot mantle rock at a constant temperature permits melting forming magma. This
process of hot mantle rock rising to shallower depths in the Earth occurs in mantle plumes,
beneath rifts and beneath mid-ocean ridges.
c. Melting as a result of the addition of volatiles (flux melting): When volatiles mix with hot,
dry rock, the volatile decreases the rock’s melting point, and they help break the chemical
bonds in the rock to allow melting.
d. Melting resulting from heat transfer from rising magma (heat transfer melting): A rising
magma from the mantle brings heat with it that can melt the surrounding rocks at the shallower
depths.
3.4 Metamorphism
The word metamorphism comes from the Greek words:

 “meta”- change
 “morph”- form
So, it literally means to change form. In geology, this is the process by which the
composition, texture, and internal structure of rocks are altered due to pressure, extreme heat, and
even introduction of new chemical substances.
Each type of metamorphism is characterized by differences in mechanical deformation and
recrystallization.
Dynamic metamorphism
 involves mechanical deformation like shearing and grinding that take place in fault
zone.
Contact metamorphism
 occurs when a body of rock is intruded by magma.
Regional metamorphism
 the alteration of rock by both thermal and mechanical means over a whole region.
3.5 Different Igneous Rock Types
a. Basalt and basaltic magma: form when hot rocks in the mantle slowly rise and encounter
lower pressures. This leads to decompression melting (melting due to reduced pressures).
This commonly occurs along places where plates are moving away from each other (i.e.,
extensional plate boundaries such as continental rifts and hotspots. This type of magma
has low viscosity, low silica, high iron, and low volatile (H2O) contents.
b. Rhyolite and rhyolitic magma: formed by either (1) melting of mantle fluxed by water and
sediments carried into the mantle in subduction zones; and /or (2) interaction of mantle
derived basaltic magmas with continental crust. The magma is highly viscous with
relatively high silica, low iron, and high volatile (H2O) contents.
c. Andesite and andesitic magma: Andesitic magmas maybe formed in a variety of ways:
some are formed when water and sediments on the ocean floor are pushed into the mantle
along subduction zones, leading to melting in the mantle. Others are formed when hot basaltic
magma interact with continental crust on the way to the Earth’s surface, which likewise leads to
melting. The silica, iron and volatile (H2O) contents and viscosity are intermediate between
basalt and rhyolite.
Activity
Chocolate Mantle Convection
I. Objective:
 To illustrate how heat works in the mantle.
II. Materials:
 PPE
 Pan
 Chocolate powder/cocoa
 Candle
 water
III. Procedure:
1. Put water in the pan. Sprinkle it with chocolate powder until the top is thickly covered
with dry powder.
2. Slowly put it on the pan holder. Light the candle and place it under the center of the
pan.
3. Let it boil for few minutes. Observe what happens.
IV. Guide Questions:

1. How is heat transferred in the activity? Give evidence for your answer.
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2. How does this activity relate to the formation of magma?
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II. I. TOPIC: Movement of the Earth’s Crust

 Plate Tectonic Theory
 Continental Drift Theory
 Seafloor Spreading
 Folds and Faults
The learner shall be able to:

 Explain how the movement of plates leads to the formation of folds and faults.
(S11/12ES-Id-22)
 Describe how layers of rocks (stratified rocks) are formed. (S11/12ES-Ie-25)
 Describe the different methods (relative and absolute dating) to determine the age of
stratified rocks. (S11/12ES-Ie-26)

1. Explain how the continents drift.
2. Explain how the seafloor spreads.
3. Discuss how the movement of plate leads to the formation of folds and faults.
To accomplish exercises and activities, you need the following: black pen, pencil and/or
other writing materials and other available references.

City, pp. 22-26

Street, Cubao, Quezon City, Metro Manila, pp. 36-42
3.6 Deformation of the Earth’s Crust
A.Plate Tectonic
 Explains that the lithosphere was so brittle that it was divided into major plates considered
to be floating over the hot liquid asthenosphere.
7 Major Plates
1. North American Plate
2. South American Plate
3. Pacific Plate
4. African Plate
5. Eurasian Plate
6. Australian Plate
7. Antarctic Plate
Aside from being divided into several plates, these plates move across Earth’s surface, each in
diff. directions from their neighbors. They glide slowly over the weak asthenosphere at rates
ranging from one to about 18 cm a year. As these plates move, they bump and grind together at
their boundaries, leading to the formation of various landforms.
As discussed earlier, the lithosphere is divided into plates that are constantly moving in diff.
directions. As a result, it leads to the formation of plate boundaries.
3 Types of Boundaries
Transform Fault Boundary

 occurs when two (2) plates slide or grind past each other
Divergent Boundary
 occurs when two plates move away from each other
 creates a rift valley
Convergent Boundary
 occurs when two plates come together or move towards each other.
B. Continental Drift Theory
Alfred Wegener
o German meteorologist
o Created the map of the Earth by fitting the continents into one.
o Claimed that earth used to have only one supergiant and land mass
where all continents came from.
o He called this land mass Pangaea, meaning “all land” that existed about
225 million years ago, wherein it is surrounded by an ocean mass called
“Panthalassa”.
Since then, as explained in the plate tectonic theory, the continents were constantly
moving that resulted to the splitting of the supercontinent in to two major continents.
4 Major Continent
Laurasia
 comprised the northern continents of today’s times.
Gondwanaland
 comprised the continents in the present southern hemisphere.
The continents further moved, eventually leading to the seven continents that we have at
present.
Evidence to Continental Drift Theory

1. Jigsaw puzzle fit of continents
2. Similarity of fossils found in different continents
Glossopteris
- a late Paleozoic plant found in rocks on all five continents.
Lystrosaurus
- early Triassic terrestrial mammal-like reptile
- about 1 meter long with two long teeth protruding from the upper jaw
Cynognathus- early Triassic terrestrial mammal-like reptile
- about 1 meter in length
3. The rock types and structures that match across continents
C. Seafloor Spreading
 proposed by marine geologists Robert S. Dietz and Harry H. Hess
 states that the oceanic crust is created as the seafloor spreads apart along mid-ocean
ridges.
 researchers used sound waves to discover under water system of mountain (ridges)
 they saw that the ocean floor was not flat instead it is filled with mountain ridges
1.2 Folds and Faults
Folds
 bent rock layer or series of layers that are originally horizontal and subsequently
deformed.
2 Types of Folds
Anticline
 fold in the sedimentary strata, resembling an arch.
Syncline
 a linear downfold in the sedimentary strata.
Faults
 fractures in the crust along which appreciable displacement has occurred on a scale from
centimeters to kilometers.
Graben
- valley formed by downward displacement of the fault-bounded block.
Horst
- elongated, uplifted block of crust bounded by faults.
4 Types of Faults
Normal fault
 a dip slip fault in which the rock above the fault plane has moved relative to the
rock below
Reverse fault-
 a dip slip fault in which the material above the fault plane moves up in relation to
the material below
Trust fault
 a reverse fault with dip less than 45 degrees
Strike-slip fault
 a fault on which the movement is horizontal
Activity
Continental Jigsaw Puzzle
I. Objective
 Fit the edges of the continents to one another
II. Materials
 Jigsaw puzzle
 Glue
 scissors
III. Procedure
1. Get a map and cut the continents using scissors.
2. Fit the edges of the continents to one another.
3. Explore on the plants and the animals that can be found at the edges of the continents,
IV. Guide Question
1. Did the edges of the continents fit together? What can you say about it?
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2. Do you agree or disagree with the theories on the movements of the Earth’s crust?
Support your answer.
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3. What can you conclude from this activity?
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III. I. TOPIC: History of the Earth

 Age of the Earth
 Rocks and Fossils
 Rocks, Fossils, and the Geologic Time Scale
 Subdivisions of Geologic Time

 Explain how relative and absolute dating were used to determine the subdivisions.
(S11/12ES-Ie-27)
 Describe how the Earth’s history can be interpreted from the geologic time scale
(S11/12ES-Ie-29)

 Acquire familiarity with the Geologic Time Scale.
 Describe how relative and absolute dating was used to subdivide geologic time.
 Appreciate the immensity of geologic time and recognize that the Earth has a very long
history.
 Identify the timing and duration of the major events in Earth’s History.

City, pp. 26-28
Earth and Life Science Teachers Guide, pp.130-33 & pp.135-140
4.1 Age of the Earth
The Earth has a very long history — 4.6 billion of years of history.
The age of the Earth is based on the radioactive isotopic dating of meteorites.
 Meteorites represent primitive and undifferentiated (unaltered) solar system
material
 The Earth differentiated or separated into the crust, mantle, and the core. Dating
the Earth’s crust provides the age of the crust and not necessarily the whole Earth
The oldest dated rock from the Earth is only ~3.8 billion years
old.
Rocks and Fossils
Petrology
 A branch of geology that deals with the origin, composition, structure
and classification of rocks.
Stratigraphy
 The study of rock layers (strata) and layering (stratification)
Paleontology
 The study of fossils to determine how they have evolved and interacted with
the environment.
a. The history of the Earth is recorded in rocks, but the rock record is inherently incomplete.
Some of the "events" do not leave a record or are not preserved. Some of the rock record may
have also been lost through the recycling of rocks (Recall the rock cycle)
 The rock record is not a video documentary of Earth’s History. A large amount of
analysis and interpretation is required to extract information from rocks.
b. Fossils- Preserved in rocks are the remains and traces of plants and
animals that
have lived and died through-out Earth's History.
 The fossil record provides scientists with one of the most
compelling evidence of
Charles Darwin's Theory of Evolution. (Increasing complexity of
life through time).
Relative Dating
 Layers where the fossils are found tells a scientist the relative
age of fossil.
Estimating age of fossil by its position in the rock layers.
Absolute Dating
 When scientists want to determine the age of a fossil more
precisely, they use
absolute dating to get an exact age. It is a method of
measuring age of object in years.
Rocks, Fossils, and the Geologic Time Scale

Geologic Time Scale
 the timeline of the History of the Earth, is based on the rock record.
 subdivided into hierarchal intervals, the largest being Eon, followed by Era,
Period, and Epoch, respectively
 subdivision of Geologic time is based on signiﬁcant events in the Earth’s History
as interpreted from the rock record.
Subdivisions of Geologic Time
Precambrian Time
 Our planet was spinning rapidly, and it looked like an alien planet
 Molten lava was flowing, and it took only six hours for a day to last.
 All the elements are in disorder.
 Gravity made all things in order.
 The heavier elements forming the core and the lighter materials floating and turning into
crust.
 The molten iron and nickel core created a magnetic field that protected the Earth from
harmful charged particles in space and allowed life to span.
 About 4.5 billion years ago, the planet experienced a turning point as it was hit by an
object as huge as Mars. The impact tilted the Earth’s axis of rotation, creating seasons and
provided stability to the planet
 Some of the molten debris created another sphere moving around the Earth now known as
the moon.
 The tilted axis of the Earth lengthens the day into 24 hours and cools down the Earth.
 About 4.4 billion years ago, the Earth’s surface was too hot, vaporizing water into steam.
 As the Earth started to cool down, rain poured down from the sky for millions of years,
creating the different bodies of water.
 In these bodies of water, abiogenesis took place.
 Key elements combined forming the foundation of all life forms – the DNA.
 These molecules created the first organism: the cyanobacteria.
 These microorganisms evolved and later developed the ability to harness the energy from
the sun ad produced the most essential of gases, the oxygen.
 These oxygen molecules occupied the primeval ocean and reacted with iron, forming iron
oxide, constituting our major land mass.
 Later, they escaped into the atmosphere, creating the ozone layer that further protected us
from the harmful radiation of the sun.
 Large solid continents appeared, making the crust more suitable for living organisms. This
leads to Cambrian explosion.
Palaeozoic Era
 About 550 million years ago, with oxygen in the primeval ocean
and the atmosphere,
marine communities flourished.
 Early fishes and aquatic plants developed.
 Plants began to occupy the land and soon some forms of fishes
also conquered the land.
 The first amphibians emerged from the ocean and lived on land.
 The amphibians could only reside near water from them to deposit their eggs. Later they
developed the ability of producing hard shells allowing them to carry their eggs anywhere
on land.
 Reptiles and insects emerged.
 About 250 million years ago, volcanic activity filled up the atmosphere with carbon
dioxide.
 Species that evolved during the Cambrian rime got extinct, leading to Permian extinction.
 This marked the end of Paleozoic era and the new era emerged, giving birth to new
dominant species.
The mass extinction event which leads to the extinction of the dinosaurs occurred around
66.4 million years ago marks the boundary between the Mesozoic Era (Age of the Reptiles) and
the Cenozoic Era (Age of Mammals). This mass extinction event may have been pivotal in the rise
in dominance of the mammals during the Cenozoic Era.
Mass Extinction
 many species died out completely, or became extinct at the
end of each era
 when species is extinct, it does not reappear
 periods when many species suddenly become extinct are
called mass extinction
 Most scientists think that the extinction of the dinosaurs
happened because of
extreme changes in the climate on Earth
 These changes could have resulted from a giant meteorite
hitting the earth, or
forces within causing major earthquakes and volcanic
eruptions
 Extinction is a normal part of the evolutionary process and
most species that
have ever existed are not living today. The normal loss of
species through time is
generally balanced by the rise of new species. Mass extinctions, however,
disrupt this balance – representing times when many more species go extinct that
are replaced by new ones
Mesozoic Era
 Also known as the “age of dinosaurs”.
 Gymnosperms emerged and the land was dominated by reptiles.
 Mammals started to evolve too but were held back by the
dinosaurs.
 The supercontinent Pangaea began to separate.
 The dominance of the dinosaurs faced an end as the asteroid hit
surface of the Earth,
causing mass extinction of the dinosaurs and giving way for
mammals to flourish and new era to emerge.
Cenozoic Era
 Sometimes called “Age of Mammals”
 About 65 million years ago, the continued evolution of mammals,
birds, insects,
and flowering plants took place.
 Mammals became the dominant species and the first primates
evolved.
 Major crustal movement occurred during this era, creating
mountains like the
Himalayas, connecting North and South America. As these two
continents,
connected, it disrupted the ocean current in the Atlantic, altering
the climate
and forming the ice age.
 As the Earth cooled down, our primate ancestors inhabited the warm climate
of the tropics.
 About 10 million years ago, new plant species—the grasses – emerged and
dominated the land, giving way to grassland.
 Early primates inhabited most of the treetops but as the grassland emerged, they moved to
explore it. With fewer trees, the apes adapted and moved into grassland. With tall grasses,
they started walking on two feet and free hands. They later evolved to become the first
humans: the hominid.
 From that day on until present time, humans dominated the planet.
Directions: Classify the following events in Earth’s geologic history according to the era where they
occurred. Arrange them chronologically under each era.
a. abiogenesis
b. domination of dinosaurs
c. domination of mammals
d. asteroid impact
e. collision of a huge mass on Earth, resulting to the formation of the moon
f. formation of the Earth’s atmosphere
g. emergence of cyanobacteria
h. evolution of humans
i. flourishing of gymnosperms
j. Pangaea
k. emergence of first amphibians
l. long duration of rain, resulting to the formation of the ocean
m. crustal formation
Precambrian Era Paleozoic Era Mesozoic Era Cenozoic Era

I. TOPIC: Natural Hazards

Natural Geologic Hazards
 Volcanic Eruptions
 Earthquake
Natural Hydrometeorological Hazards
 Tsunami
 Typhoons and Hurricanes
 Storm Surge
 Floods

 Describe the various hazards that may happen in the event of earthquakes, volcanic
eruptions, and landslides (S11/12ES-If-30)
 Using hazard maps, identify areas prone to hazards brought about by earthquakes,
volcanic eruptions, and landslides (S11/12ES-If-31)
 Identify human activities that speed up or trigger landslides (S11/12ES-If-33)
 Using hazard maps, identify areas prone to hazards brought about by tropical
cyclones, monsoons, floods, or ipo-ipo (S11/12ES-If-36)

 Describe and explain the hazards associated with earthquakes
 Identify and give examples of possible geologic hazards associated with earthquakes
 Identify and understand how certain human activities can hasten the occurrence of
landslides.
 Identify and classify the different types of hydrometeorological hazard.
 Evaluate their community for potential hazards induced by extreme atmospheric and
hydrologic conditions

City, pp. 39-46
The previous chapters have provided us an understanding of our Earth’s structure

and changes it has undergone. This chapter will now focus on the discussion of the
different natural hazards—geological and hydrometeorological—and possible mitigation
and adaptation.
1.1 What are Natural Hazards?
Natural Hazards
 Severe and extreme weather and climate events that occur naturally in all
parts of the world (World Meteorological organization)
Natural Disasters
 When people’s lives and livelihoods are destroyed
Geologic location & tectonic setting
 reason why Philippines frequently experiences a lot of natural hazards
1.1.1 Natural geologic Hazards

 Movement of the plates and volcanic eruptions
 Toppling down of soil
 Degradation of rocks beneath the ground
 Common natural events
 Threat to properties, plants, animals & especially humans
 Formidable forces that cannot be prevented to occur, but effects could be reduced
 It can be done by means of understanding the nature and how to adapt to situation
to reduce
Volcanic Eruptions
Volcanoes
 like mountains and hills
 formed by either the converging of
tectonic plates or the accumulation of
materials erupted through one or more
openings on the Earth’s surface
 most have steep sides; some can be
gently sloping mountains
or can be flat tablelands or plateaus
 found above sea level and even along the ocean floor
 Accumulated by the molten rocks- MAGMA
 Magma is formed deep because of high temperature and pressure &
rises through openings or cracks known as FISSURE VENTS
 Molten rocks flowing out of a volcanic vent are called LAVA
Difference of volcanoes
 shapes and sizes
 depending on the makeup of the magma
 how they erupt
Types of volcanoes
 Cinder
 Composite
 Shield
 Calderas
 Plateaus
How do volcanoes erupt?

1. begins when the magma deposited inside the volcano rises up through the vent,
forms ever-larger blobs and moves towards the surface of the Earth
2. as magma continues to move up, it accumulates in one or more underground
storage known as magma reservoirs
3. the magma that builds up pressure within the reservoirs may suddenly erupt onto
the surface releasing various volcanic material
Volcanoes erupt differently:

 composition of the magma
 amount of gas in the magma
 type of vent
Explosive Non- Explosive
Types of eruptions
1. Explosive
 volcanic materials are
ejected
2. Non-explosive
 volcanic materials flow on the surface
Active Volcano
3 Common types of volcanic materials that may be ejected:
 Lava
- may break into the surface or flow rapidly down the
slope
- rarely life threatening but can cause great damages
to property
 Tephra or Pyroclastic Materials
- rock fragments thrown airborne during an explosive
eruption
- can cause greater damage and casualties to a
nearby town
- rarely life threatening but can cause great damages to property
 Gases & Volcanic Ash
- most threatening
- consist of water vapor, carbon dioxide, and sulfur
dioxide with a mix of smaller amounts of
hydrogen chloride and hydrogen fluoride.
- It results to acid rain when these gases mix with
water in the atmosphere
- can cause pulmonary ailments
- collapse roofs and damage crops
 Lahar travels more quickly than lava, thus it is more life-threatening and produces greater
damages.
Eruption of Mt. Pinatubo (1991)

 2nd largest eruption in the 20th century
 rains and extreme precipitation rate after the eruption
brought at least one-centimeter-thick lahar that
deposited in Luzon, particularly in the major parts of
Pampanga and Zambales
Eruption of Mt. Krakatoa (Krakatau in East Java)
 more cataclysmic phenomenon occurred in Indonesia
 two days explosions on August 26-27, 1883
 2/3 of the island had been destroyed
 one of the most destructive and deadliest volcanic events in recorded history
 generated tsunamis and reduces global temperature
Types of Volcanoes
 Active
- volcanoes that have erupted within the last 100 years
 Potentially active
- morphologically young-looking volcanoes but with no historical records of
eruptions
 Inactive
- have no record of eruptions
Earthquakes
 refers to the movement or shaking of the ground on the
Earth’s crust.
 another natural hazards that may cause disaster
 results from the dynamic release of elastic strain energy that
radiates seismic waves
Origin
 volcanic activity
 tectonic-related
Elastic-Rebound Theory
 Derived from the concept of a spring
 When a spring is compressed, it gains energy & releases the energy when the
stress is removed, resulting it a wavelike movement.
 Earth is made up of tectonic plates that are constantly moving

 As the plates meet, stress accumulates and later, energy is released from the stress in the
form of ground movements
 Additional movements of the plates may occur accompanying the main shock in order to
gain stabilization of the plates
Aftershocks
 Additional movements
Geologic location and tectonic setting

 reason why the Philippines is prone to earthquake
 part of the Pacific Ring of Fire (consist of various faults and trenches)
Three (3) major earthquake generators in the Philippines

1. Philippine Trench- 1, 320 km & located east of the Philippines
2. Manila Trench- 560 km and located west of Luzon
3. Philippine Fault Zone (PFZ)- 1, 200 km across the archipelago
 These faults were responsible for the earthquakes which the country has experienced in
recent history
Active Faults in Manila

1. 10-km East Valley Fault
2. 90-km West Valley Fault
 Acc. PHILVOCS, the longer the fault, the higher is the magnitude of the earthquake that it
can generate.
 Movements along these faults pose a threat to the residences and infrastructures in Metro
Manila.
Seismometer
 instrument use to record earthquakes
Epicenter
 Epicenter of an Earthquake is the location directly above
the hypocenter on the surface of the earth
Hypocenter
 Hypocenter of an Earthquake is the location beneath the
earth’s surface where the rupture of the fault begins.
Magnitude
 Is a measured value of the earthquake size. The magnitude
is the same no matter where you are, or how strong or weak
the shaking in various location.
Intensity
 a measure of the shaking created by the earthquake and this

value does vary with location
Landslides
 Movement of mass of Earth (soil, mud, rocks, or debris) down a

slope
 Pertains to the wide variety of processes resulting from the
downward and outward movement of slope- forming materials
including rocks, soil, artificial fill, or a combination of these.
 these processes may be categorized as erosion, but on a large
scale, they are known
as landslide.
 a common cause of landslide is slope saturation by water
 in the Philippines, the usual cause of landslides is rainfall, which can be resulted to
flooding that can lead to a landslide.
 another common cause of landslides is Earthquake.
 whenever tectonic plates move, the crust above them also moves. As such when quakes
generate under a steep slope, soil slips or topples, triggering a landslide
Causes of Landslides
 Saturation by water
 Earthquake
Human Activities
 Deforestation
 Cultivation
 Construction
 Blasting
 Logging
1.1.2 Natural hydrometeorological hazards
 can be rain-related
 majority of the natural disasters in the
Philippines are hydrometeorological induced
Tsunami
 the sudden rush of water forms waves
 generated when the epicenter of an earthquake is
located beneath the sea
 the sea floor drops as a direct result of an earthquake
on the Earth’s crust, water rushes into filling up the
depression
 the height of the wave greatly depends on the depth of
the depression &
velocity of the rushing water
 the deeper the depression, and the faster the water move towards the shore, the
bigger the waves that are created
Typhoons and Hurricanes

 most destructive natural hazards
 bring the great damage and number of casualties
 both are generally known as tropical cyclones
 differ only in terms of where they were formed
 Typhoons
- develop in the Northwestern part of the Pacific Ocean
- includes the Philippines and neighboring Asian countries
 Hurricanes
- form in the Central or Northeastern part of the Pacific or in the North
Atlantic, Caribbean Sea, or Gulf of Mexico
How do tropical cyclones develop?

There are six (6) main requirements for a tropical cyclone to form:
1. a sufficiently warm sea surface temperature
2. atmospheric instability
3. high humidity in the lower to middle levels of the atmosphere
4. enough Coriolis force to develop a low-pressure center
5. pre-existing low-level disturbance
6. low vertical wind shear
Tropical Cyclone
 described based on its sustaining wind and speed and classified based on its intensity
 it derives its energy from the latent heat of condensation, which makes the cyclone
form over the oceans and weaken rapidly on land
 typhoons generals weaken rapidly on land because the main fueling ingredient that
sustain it—the moist air of the ocean—cannot sustain it anymore
 has a central sea-level pressure of 900 mb or lower and surface winds often exceeding
100 knots and reaches its greatest intensity while located over warm tropical waters
and begins to weaken as it moves inland.
Classification of tropical cyclones according to the strength of the associated winds

Tropical Cyclone Wind Strength
Tropical Depression (TD) maximum sustained winds of up to 61 km per hour (kph) or less
than nautical miles per hour (knots)
Tropical Storm (TS) maximum wind speed of 62-88 kph or 34-47 knots
Severe Tropical Storm (STS) maximum wind speed of 89-117 or 48-63 knots
Typhoon (TY) maximum wind speed of 118-220 kph or 64-120 knots
Super Typhoon (STY) maximum wind speed exceeding 220 kph or more than 120
knots
Typhoons form in the warm, moist air of the tropics mostly coming from the ocean. Every
few days, thunderstorms form in this environment and move with the winds. The moisture from the
warm ocean “feeds” the thunderstorms, converting the moisture to heat. These thunderstorms
have low pressure surfaces that attract more moisture from the ocean, making them larger.
Coriolis force
 makes the air mass rotate counterclockwise in the Northern Hemisphere
 makes the air mass rotate clockwise in the Southern Hemisphere
“Eye”
 where the winds are calm
“Eyewall”
 strongest winds occur
Storm Surge
 abnormal rise of water brought by a storm
 water level increases its height beyond the normal tide and
moves inland
 occur during the storm
 caused by a storm
 cause greater damage along the coast
Floods
 overflow or large accumulation of water that submerges the
land
 occur when water from the bodies of water escapes its usual
boundaries and therefore overflow
 occur also due to an accumulation of rainwater on saturated
ground
Types of Floods
1. Areal flood
- caused by lowland areas
- categorized as flood plains
Flood plains
- serving as catch basin of water coming from the highlands or mountains
- a flat area with areas of higher elevation on both sides and is therefore
prone to flooding
2. Riverine flood
- due to the overflowing of water from rivers and
streams
- occurs when rivers become narrow and shallow and
cannot hold too much water
3. Coastal or Estuarine flood
- some parts are remains flooded even without rain
- due to inability of estuaries or openings to coastal
areas to release the water faster than the intake of
water
- affected also by the changing tides
4. Urban flood
- Result of non-functional drainages and canals in urban areas
Effects of Flood
 health risks
 damage to buildings and structures
 loss of life
 economy of the city/country
A. Each student will come with a campaign material for their neighbor in the community.
The campaign material must:
a. contain information on the potential danger of earthquake hazards within the

community
b. be a brochure, poster, or a PowerPoint presentation.
Criteria:
 Color Harmony- 15%
 Creativity- 20 %
 Originality- 25%
 Relevance to the Theme- 30%
 Visual Impact- 10%
TOTAL- 100%
B. Each student will interview their respective barangay officials and find out the
following:
1. Areas in their barangay susceptible to hydrometeorological hazards (e.g., flooding,

storm surges and landslides)
2. Preparation and response of the Barangay to these hazards
 Location of evacuations site/s
Location of nearest emergency health service (e.g., hospitals etc.)

I. TOPIC: Introduction to Life Science

 Theory of Special Creation
 Theory of Spontaneous Generation
 Abiogenesis
 Scientist who disproved Spontaneous Generation
 Biogenesis
 Unifying Themes

 Explain the evolving concept of life based on emerging pieces of evidence.
(S11/12LT-IIa-1)
 Describe how unifying themes (e.g., structure and function, evolution, and
ecosystems) in the study of life show the connections among living things and how
they interact with each other and with their environment (S11/12LT-IIa-3)

1. Discuss the historical development of the concept of life including theories,
experiments and evidence.
2. Describe the conditions on early Earth that made the origin of life possible and the first
life forms.
3. Discuss the unifying themes of life and how they are interconnected.

City, pp. 56-64
The fact of life has since intrigued human, prompting them to ask questions as regards its very
origin: Where did life come from? How did life come from? How did life happen in Earth? Why is
there life on Earth?
In this chapter, you will learn how philosophers and scientists tried to answer these
questions. You will understand that through time, different hypotheses have been proposed, tested,
and reevaluated, and these hypotheses have only led to more wonders about life.
You will further understand what life science all is about—it is the study of the origin,
process, and interactions of life.
1.1 Where and How Did Life Begin?
In the ancient times, human beings have asked the questions: Where did I come from?
Where did life originate? Drawing inspiration from their natural geographical landscapes, human
beings have tried to answer these questions in different ways. The inquiries about how life came
about are not easy to answer, so some thinkers looked up in the heavens to search for possible
explanations. Meanwhile, others examined their surroundings to find some clues. Their proposals
and findings now form a body of hypotheses and theories that provide a deeper understanding of
the concept and origin of life.
Theory of Special Creation
Earliest hypotheses about the origin of life. There is
no found evidence to support this explanation other than the
belief that a Supreme Being or supernatural deities brought
the universe and all living organisms into existence. This
core
belief in most of the major religious in the world & most widely accepted explanation about the
origin of life. Figure 1.1 Christians believe that God
created the universe and the world, including
all living things, in just six days.
Theory of Spontaneous Generation

Similar to the creation theory in that it states that living things just suddenly came into
existence. This theory claims that living things can spontaneously arise from non-living things. The
Greek philosopher and biologist Aristotle are one of the firm believers of this theory. His support for
this theory comes from his belief that all things are full of soul so that, living or nonliving, matter
could generate life. As such, he believed that some insects develop from manure as evidenced by
flies appearing in animal dung. He also believed that oysters generate from slime, barnacles from
rocks, and some insects from morning dew falling on leaves, animal flesh, human hair, vegetation,
snow, old wax, dried sweat, fire, or books.
The ancient Egyptians also believed in spontaneous generation. They observed that after
the Nile River inundate areas along the river, it left behind nutrient-rich soil, enabling them to grow
crops. Along with the mud, frogs and meadow mice plagued the areas that had been flooded,
leading ancient Egyptians to conclude that the Nile River could spontaneously give rise to many
forms of life.
Abiogenesis
The theory that living things can spontaneously generate from living or decaying matter.
Abiogenesis was popular until the Renaissance period. This idea was backed up by evidence,
which you will examine in the following activity. (Proceed to activity sheet. Activity 1, Activity 2, and
Activity 3)
In the late 17th century, several scientists disproved the theory of spontaneous generation
by putting the maggot observation under further investigation and performing other experiments.
Scientist Who Disproved Spontaneous Generation
Francisco Redi
- Italian physician
- On 1668 he disproved the theory of spontaneous generation through the
same experiment (activity 2)
- He also used different kinds of meat, such as snake, fish, eels, and veal Francisco Redi
Lazarro Spallanzani
Lazaro Spallanzani
- Italian scientist
- Performed the experiment (activity 3)
- Disprove the theory of spontaneous generation
Louis Pasteur
- French chemist
- In 1864, he finally put an end to the theory of spontaneous generation
- He conducted an experiment like that by Spallanzani
- He put broths in a long swan-necked flask
- Then he boiled the broths to kill any microorganisms
- He left the flask uncovered for some time and no microorganism appeared
Louis Pasteur
- He concluded that the flask with the bent/curved neck filtered the dust particles in the air
Figure 1.2 Louis Pasteur discovered that the

source of microorganisms for fermentation,
such as for milk, sugar, and wine, was the air.
In the experiments conducted, you found out that living organisms did not spontaneously arise
from nonliving matter. Rather, foreign living organisms brought forth the maggots and
microorganisms. This is an example of biogenesis.
Biogenesis
- The theory that life comes only from pre-existing life and therefore does not explain the
origin of life per se.
In the late 18th century, some scientists thought that if life on Earth did not come spontaneously
out of nonliving things, perhaps it came from outside of Earth—just like how the maggots were
brought to the meat pieces through the eggs which the flies laid on the meat in Redi’s experiment
and how the microorganisms were transported to the broths from the germ-laden dust in the air.
Theory of Panspermia
According to theory of panspermia, life exists in the Universe and that life on Earth may
have been transported to our planet from somewhere else in the Universe. A microbe-containing
Martian meteorite that was found in Antarctica in 1984 after they got blasted off their home planet
about 15 million years ago by cosmic impacts not only give clues as regards life on Mars, but also
suggest that Earthlings were originally Martians. Other scientists have also suggested that life
might have been transported to Earth from other star systems via comets, meteorites, and
asteroids as such extra-terrestrial objects that have been landed on Earth were found to contain
organic compounds, including amino acids. If you remember, organic compounds are compound
that primary contain carbon.
Svante Arrhenius
- In 1903, he hypothesized that the “seed of life” came in the form of
bacterial spores which were spread through space and transported
from one object to another by radiation pressure.
Panspermia
- Greek word Svante Arrhenius
- Means “seeds everywhere”
- Hence, the idea is that “seeds of life” were scatted in the Universe and that life was seeded
on Earth from outer space.
Organic compounds may be found on the extra-terrestrial objects, but organic matter is not life.
Rather, organic compounds are the building blocks of life. Hence, although the panspermia theory
gives us strong clues about how life began on Earth, it does not really answer the question “What
is the origin of life?”
Theory of Evolution
- The idea that life was the result of slow and gradual chemical processes
- In early 20th century scientists thought that perhaps life generated because of the physical
events and chemical processes
Scientists who support this theory believe that the chemical processes that eventually gave
rise to life took place on Earth about 3.8 billion years ago. Geologists believe that between 4.35 to
3.38 billion years ago, Earth was enduring heavy meteor bombardment. During the Earth’s
primitive form was hot and violent: volcanoes were forming and ejecting gases, and the planet was
being shrouded by a cloudy and carbon dioxide-laden atmosphere. By 3.8 to 3 billion years ago,
the first organisms started to appear. But how?
Alexander Oparin and John Burton S. Haldane

- a Russian biochemist and British-Indian geneticist
- in 1920s, independently hypothesized that the first
organisms called “primordial soup” appeared in
the oceans, during a period when the atmosphere
was reducing
- These microorganisms contain H2 (hydrogen),
H2O (water), NH3 (ammonia),
CH4 (methane), and CO2 (carbon dioxide) – compounds that synthesized
upon exposure to energy, such as lightning and ultraviolet (UV) light from the sun,
eventually serving as the chemical building blocks of life.
- They also assumed that there was no free O 2 (oxygen) in the atmosphere as free O2 will
react with the metals in the Earth’s crust, causing oxidation.
- The Oparin-Haldane hypothesis provides a stronger support to
abiogenesis.
Stanley L. Miller
- In 1953, under the supervision of Harold C. Urey, put the Oparin-
Haldane hypothesis into a test
- Through an experiment, now known as the spark-discharge
experiment, Miller showed that biological molecules could indeed have
been created by lightning discharges, Stanley L. Miller
which were believed to be common in Earth’s early atmosphere.
Louis Lerman
- Geophysicist
- In 1986, he suggested the bubble hypothesis for the origin of life on Earth.
- He proposed that the chemical processes that led to the evolution of life took place within
bubbles on the surface of the oceans
The bubbles were produced by erupting undersea volcanoes and vents trapped the simple
organic chemicals. When the bubbles rose to the surface and popped, the more concentrated
organic compounds were ejected into the air. Hit by lightning and UV radiation, the simple organic
molecule became more complex. The more complex organic molecules re-entered the seas
packaged in raindrops or snow. The bubble hypothesis explained how the primordial soup might
have been prepared.
1.2 What Do We Know About Life, So Far?
In the theories on the origin of life on

Earth, there are unifying themes that deepen our
scientific understanding of life. These themes
show the connections among living things and
how they interact with one another and with their
environment.
All living organisms are made up of one
or more cells.
Cell
- the basic unit of life.
- like tiny capsules that hold the biological equipment necessary to keep an organism alive
- some living organisms are very simple in structure, such as
single-celled animals, and some are very complex like the humans.Plant and Animal Cell
For an organism to function and survive, it must undergo metabolism.

Metabolism
- the sum of all the chemical reactions necessary for the maintenance of life, occurring
within and carried out in an organism
- it involves the breaking down of substances to yield energy for vital processes and the
production of other substances necessary for life
Organisms struggle not only for their own survival, but also for survival of their species. Hence,
organisms reproduce to make more of their own kind.
Reproduction
- most important concepts in life science
- the process of making new individual organisms (offspring) produced from their parents,
thereby providing for the continued existence of species
Heredity
- the process of passing traits from one generation to the next takes place
Living things also adapt to their environment as a means to stay alive.

Adaptation
- a life-sustaining process by which living organisms adjust to environmental changes
In response to such environmental changes, organisms undergo homeostasis.

Homeostasis
- maintain a constant internal environment
As living organisms adapt to their environment, they gradually change over time.
Evolution
- the process of changing into a better
- in the process, acquire traits are passed on to the next generation.
To survive, organisms interact with abiotic and biotic factors in their environment.
Abiotic factors
- non-living things in the environment
Example: water, air, and land
Biotic factors
- the living members of the biological community.
This clearly shows that organisms are interdependent on one another.

Activity 1.1
Materials:
 raw meat/raw fish
 container
Procedure:
1. Place a piece of raw meat/fish on a disposable container.
2. Leave it outside for a day.
3. Keep the meat/fish out of reach of animals (such as cats) and other people.
4. Return on the following day and check the meat/fish.
5. Observe Carefully.
Guide Question:
1. What else do you see aside from the meat?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
____________________________
2. How does this explain the theory of spontaneous generation?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
____________________________
Activity 1.2
Materials:
 3 jars (only one jar need to have a lid)
 Gauze
 Rubber band
 Three small pieces of cooked meat/ fish
Procedure:
1. Put a piece of cooked meat/fish into each jar. Label the jars A, B, and C.
2. Cover jar B with gauze. Use a rubber band to secure the gauze.
3. Leave jar A uncovered, while seal jar C with a lid.
4. Leave the three jars outside the house for several days. (3-7 days)
5. From time to time. Check out the jars and record your observations
Guide Question:
1. What have you observed in jar A? in jar B? in jar C?
Jar A:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Jar B:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Jar C:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Activity 1.3
Materials:
 Meat or vegetable broth
 Two Bunsen burners
 Match or lighter
 Two flasks
 Cork that can fit the mouth of one of the flasks
Procedure:
1. Put an equal amount of broth into the flasks. Label one flasks A, the other B.
2. Simultaneously boil the two broths using the Bunsen burners.
3. Set aside flask A, while flask B with a cork.
4. Set aside both flasks for several hours. From time to time, check out the flasks and record
your observation.
Guide Question:
1. What have you observed in flask A? in flask B?
Flask A
Flask B
Flask A:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Flask B:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Follow-up:
 Remove the cork of flask B. Set the flask aside for several hours.
 From time to time, check the flask and record your observation.
2. What did you find out?

________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________

MODULE #: 8-9 TEACHER: Mr. Bern Evora Alvis
I. TOPIC: Animal Reproduction

 Asexual Reproduction
 Sexual Reproduction
 Genetic Information
 Protein Synthesis
 Benefits and Risks of GMO

 Describe the different ways of how representative animals reproduce. (S11/12LT-
IIej-15)

4. Identify the different ways how animals reproduce.
5. Differentiate asexual reproduction from asexual reproduction
6. Explain how the information in the DNA allows the transfer of genetic information and
synthesis of proteins.
7. Describe the process of genetic engineering.
8. Evaluate the benefits and risks of using GMOs.

City, pp. 89-99
Reproduction is the process by which organisms produce offspring’s; thereby allowing the
propagation and continuation of species. The focus of this chapter is about reproduction in major
groups of living organisms, such as animals. Reproduction can either be sexual or asexual. Sexual
reproduction involves the formation of offspring by the fusion of gametes.
To further understand how characteristic traits are carried on from one generation to the next,
one should first understand how information in the DNA is carried on in the synthesis of proteins.
This leads to the study of genetic engineering which is about the alteration of the genome of an
organism to produce new traits. Since modification in the natural characteristics of organism is the
end goal of genetic engineering, we must be aware of the benefits as well as the coupled risks it
can bring.
1. Budding
This occurs when an offspring grows out of the body of the parent.
Example: hydra
2. Gemmation
This asexual reproduction happens when an organism spontaneously develops a
bulge that turns into a new organism.
Example: Sponge
3. Fragmentation
This type of asexual reproduction occurs when one part of an organism give rise to
another. In the case of the flatworms, the animal splits at a particular joint and two
fragments regenerate the missing organs and tissues.
4. Regeneration
This happens when there is a regrowth of new parts of an organism’s body to
replace those that have been damaged. Regeneration enable’s a green anole lizard
(Anolis carolinensis) to grow back a lost tail.
Regeneration
Figure 1. Asexual reproduction in animals. Some animals undergo a) budding (hydra), b)

gemmation, c) fragmentation (flatworm)l, and d) regeneration (green anole lizard)
Sexual Reproduction of Animals

In sexual reproduction, two organisms produce offspring that have genetic characteristics
coming from both parents. Through sexual reproduction, new gene combination is introduced in a
population through genetic recombination with more variation among species towards better
adaptation and survival.
There are two types of fertilization among animal organisms: external and internal
fertilization.
1. External Fertilization
This type of sexual reproduction is marked by the release of both sperm and eggs into an
external environment. It is advantageous for aquatic animals because it does not require
specialized structures (e.g., placenta), freeing them from any parental role (like nurturing the young
within the womb) and allowing the offspring to mature, adapt,
and become independent quickly. As such, there is potential
for high rate of reproduction. In addition, since it happens in
or near bodies of water, the eggs are prevented
from desiccation (dehydration), even allowing the
environment to nourish the eggs. Figure 2. External fertilization in fish
Also, the developing larvae are supplied by the egg
resources.
External fertilization occurs when the sperm fertilizes the egg outside of the organism as
shown in the spawning of fish in Figure 2. It also occurs mostly in wet environments and requires
both the male and the female to release their gametes (sex cells) into their surroundings, which is
usually water. Amphibians and fish are examples of animals that reproduce this way.
1.1 Reproduction of Animals
There are some unusual styles of reproduction in the Kingdom Animalia. Animals can
reproduce either asexually or sexually.
Do you know that it is the male seahorse that becomes pregnant and gives birth to its
young? In coral reef fishes called wrasses, if the male seahorse dies, the largest female becomes
a male. Find out other interesting facts about animal reproduction.
Asexual Reproduction of Animals

In this type of reproduction, an individual produces offspring that are genetically identical to
itself since the genetic makeup is not changed.
Several types of invertebrates, such as sponges, cnidarians, flatworms, annelids,
and echinoderm, can reproduce asexually. There are several types of asexual reproduction, such
as:
2. Internal Fertilization
In this type of sexual reproduction, the sperm fertilizes the egg within the female. It protects
the fertilized egg or embryo from predation and harsh environments. It includes three methods.
a. Oviparity
Oviparous animals retain the fertilized egg
inside the body where development occurs, and
nourishment is received from the yolk. They include
those that reproduce by laying eggs, with little or no
embryonic development within the mother.
This is the reproductive method of most fish,
amphibians, reptiles, Figure 3. A hen brooding on the eggs
insects, arachnids, birds, and egg-laying mammals.
b. Ovoviviparity
Ovoviviparous animals produce eggs that
develop within the mother’s body. When the eggs hatch within
the mother, the offspring stay within the mother for some time,
eating unfertilized eggs in the womb for nourishment.
The offspring does not have an umbilical cord to
attach the embryo to its mother. Figure 4. A snake that has hatched
Some examples of ovoviviparous animals include some sharks (e.g., basking
shark) and other types of fish, snakes, and insects.
c. Viviparity
This type of sexual reproduction is one
wherein young develop within the female and nourishment are
received directly from the mother through a placenta.
Viviparous animals, like humans and most mammals, give
birth to living young that have been nourished I closed contact
with their mother’s bodies.
Figure 5. a mother guinea pig that has
given birth to numerous Guinea piglets
1.2 How Is Genetic Information Passed on from the Parents to the Offspring?
When an organism reproduces—be it asexually or sexually – it produces for the purpose of

propagating its own kind. When a parent organism reproduces, it either makes an exact copy of
itself or leaves an imprint on its offspring. Either way, the parent’s traits are passed on to the
offspring.
Heredity is the passing on of traits, or physical characteristics, from one generation to the
next. It is the reason why children may look either like their father or their mother, or a cross from
both of their parents. Heredity also explains why puppies look like dogs, and not like cats or other
animals. It occurs among all kinds of organisms—fungi, bacteria, protists, plants, and animals.
In asexual reproduction, all the genes of an organism are inherited from a single parent
through mitosis. This explains why all offspring are genetically identical to the parent. In sexual
reproduction, an organism inherits half of the genetic information from its mother and half from its
father. Hence, the produced offspring becomes a unique individual.
All the traits that an organism possesses are encoded in the genes of the organism. A
gene is a DNA segment that contains the instructions providing all the information necessary for a
living organism to grow and live. These instructions tell what role the information will play in the
organism’s body.
In this lesson, you will recall how this genetic information flow from the DNA to build an
organism and ensure that the organism functions correctly.
1.3 Flow of Genetic Information
This genetic information characterizes the structure and function of any organisms that are
present and stored in the sequence encoded proteins, which carry out most of the functions in all
organisms. The information on the DNA is made
available by transcription of genes to mRNAs. Messenger RNAs, or mRNAs, is a class of RNA
molecules that carry information in protein in an organism. In summary, the flow goes like this:
DNA encodes RNA through transcription; the, RNA encodes proteins through translation. This is
known as the Central Dogma of molecular biology.
Figure 6. Simplified diagram showing the flow of genetic information: DNA encodes RNA through
transcription; then, RNA encodes proteins through translation
All on Earth uses a single genetic system based on DNA and RNA. The genetic
information flows from a DNA to an RNA copy of the DNA gene, to the amino acids that are joined
together to produce the protein coded for by the gene.
1.4 Protein Synthesis
The function of a gene is to specify the sequence of amino in a protein. Proteins are the
molecular workers of a cell. This means that their activities control the shapes, function, and
synthesis of carbohydrates, lipids, and nucleic acids. Information flows from the DNA found in the
genes of a cell to the proteins that specifically carry out the functions of every cell.
Proteins, in turn, are expressed as the different traits of an organism (e.g., eye color,
enzymes, and hormones). One’s physical characteristics are dictated by the genes in the
chromosomes of every cell that makes up his/her body.
Protein synthesis is one of the most fundamental biological processes. It refers to the
process in which individual cells make or generate new specific proteins. The making of proteins
makes up one of the four building block of life and are involved I just about every life process. The
process starts with instructions carried by a gene to build a particular protein.
Recall the four key players in protein synthesis: First, the DNA, which stores genetic
information; second, the gene, a sequence of DNA that encodes for a particular protein; third, the
proteins, which are large molecules, composed of amino acids; and finally, the RNA, a polymer of
nucleotides, usually single-stranded, that copies the genetic information.
Before a protein can be made, the instructions carried by a gene are first copied, by the
RNA molecule. RNA, which is usually single stranded, makes base pairs with DNA nucleotides in
this manner: cytosine (C) pairs with guanine (G), and adenine (A) pairs with uracil (U). Remember
that in RNA-DNA pairing, uracil is paired with adenine and not thymine (T).
Particularly, the mRNA serves as a copy that tells the cell which amino acids must join to
produce a protein. The process of going from protein to protein involves two steps: transcription
and translation.
a. Transcription
Just like a transcript of a speech which is a written version of an oral presentation,
transcription is the copying of a DNA gene into RNA. The process, which happens inside
the nucleus of a cell, produces a transcript of the original gene, with the RNA nucleotides
substituting for DNA nucleotides. The copy is produced by the help of RNA polymerase, a
n enzyme that bonds nucleotides together to make a new RNA molecule.
The result of transcription is the production of a single-stranded RNA molecule that
is complementary to the DNA sequence of a gene. This copy of the DNA gene is called
messenger RNA (mRNA) since it carries the message of the gene that is to be expressed.
b. Translation
After DNA is transcribed into an mRNA molecule during transcription, the mRNA
must be translated to produce a protein. In translation, mRNA, transfer RNA (tRNA), and
ribosomes work together to produce proteins. Translation is the process that converts or
translates an mRNA message into polypeptides which make up a protein.
To determine the sequence of amino acids that a gene codes, scientists use the genetic
code. It is like a dictionary that cells use to determine which amino acid will be translated from each
sequence of mRNA codons. A codon is a sequence of three nucleotides that codes for an amino
acid. Amino acids are strung together to form a polypeptide. Finally, polypeptides form a properly
folded molecule called protein.
Each code word is a unique combination of three letters that will be interpreted eventually
as a single amino acid in a polypeptide chain. There are 64 code words possible from an
“alphabet” of four letters.
Of the 64 codons, 61 codons specify amino acids and three (UAA, UAG, UGA) serve as
stop signals to mark the end of protein synthesis. The codon AUG, which codes for the amino acid
methionine, serves as a start signal for the beginning of translation.
Figure 7. The genetic code
Multiple codons may also specify the same amino acid. For example, the codons CUU,
CUC, UCA, and CUG all specify leucine. The abbreviations and names of all 20 amino acids are
listed in the table 4.1 below.
Table 4.1 List of Amino Acids and their Abbreviations

Amino Acid Abbreviation
Alanine Ala
Arginine Arg
Asparagine Asn
Aspartic Acid Asp
Cysteine Cys
Glutamic Acid Glu
Glutamine Gln
Glycine Gly
Histidine His
Isoleucine Ile
Leucine Leu
Lysine Lys
Methionine Met
Phenylalanine Phe
Proline Pro
Serine Ser
Threonine Thr
Trytophan Trp
Tyrosine Tyr
Valine Val
A DNA sequence (e.g., AAC-GCC-GUU), which corresponds to an amino acid sequence
(i.e., Asn Ala Val), represents a genotype, a set of genes in the DNA responsible for a particular
physical trait. The phenotype is the physical expression or observable characteristic of that trait.
1.5 Can New Traits Be Introduced?
In the previous lesson, you have learned that naturally, organism’s inherent traits only from
their parent/s. However, as advancements in biotechnology progresses, scientists have made new
discoveries and innovation as regards genetics. Today, through genetic engineering, organisms
can artificially acquire traits from a different organism other than its parent/s.
1.6 Genetic Engineering
In 2007, a team of South Korean scientists, led by Kong II-keun at Gyeonsang National
University, clones three fluffy white Turkish Angora cats after altering a gene so that the felines will
glow in the dark.
The scientists extracted skin cells of the mother cat (donor) and modified the genes by
adding red fluorescence protein genes to the skin cells. Then they transplanted the gene-altered
skin cells into egg cells, which were implemented to the womb of the mother cat. Two of the cats
were born in January and February 2007, while the other was stillborn. Still, all of them glowed red
under UV light.
The procedure done by the scientists could be used for developing treatments for both
animal and human genetic diseases.
The cloning of the glow-in-the-dark cats is an example of genetic engineering. Genetic
engineering is the modification of an organism’s DNA by artificial means to give the organism new
traits. The resulting organism, such as the glowing Turkish Angora cat, is called a transgenic or
genetically modified organism (GMO).
Genetic engineering is not the same as cross breeding, where genes are exchanged
between closely related species, as in cross breeding a liger (hybrid of a male lion and female
tiger) or a tigon (hybrid of a male tiger and female lion). In genetic engineering, genes from an
entirely different species other than the parent or any closely related species are introduced to a
cell.
The principle of genetic engineering is based on recombinant DNA technology.
Recombinant DNA is the DNA that contains genes from more than one organism. In genetic
engineering, bacteria are commonly used because they have tiny rings of DNA called plasmids.
The process of recombinant DNA technology shows the following:
1. An isolated gene from a gene donor (e.g., the insulin gene) and
bacterial plasmid from a plasmid donor is
cut by a restriction enzyme
.
2. Certain enzymes can “paste” or “install”
the genes you want into the plasmid or
other organism.
3. The DNA can be reinserted and contain

the recombinant DNA, which will produce
the polypeptide it code for.
4. After a gene is inserted to a plasmid, the

genetically engineered plasmids can be put
into a bacterium.
5. The bacteria will act like a gene factory

that makes copies of the plasmid-making
new gene and gene’s product. Figure 8. Recombinant DNA technology
6. The resulting organism (bacteria) is called transgenic organism.

Organisms that have altered genomes are known as transgenic.
Most transgenic organisms are generated in the laboratory for
research purposes.
1.7 Production of Novel Products
Because of the advance sin biotechnology, genetic

engineering now refers to the technologies used to alter or modify
the genetic makeup of cells to produce improved or novel organisms
and organic products.
In the animal kingdom, genetic engineering is also applied.
One example of a GM animal is the transgenic chicken. Transgenic
chickens grow faster than sheep and goats and large numbers can
be grown in close quarters, and they synthesize several grams of
protein in the “white” of their eggs.
Another is the transgenic pig which has also been produced
by fertilizing
a normal egg with a sperm cell that has incorporated foreign DNA. This procedure, called sperm-
mediated gene transfer (SMGT) may someday be able to produce transgenic pigs that can serve
as a source of transplanted organs for humans.
In doing the procedure, scientists choose the specific gene that they need for the situation,
and then it is fused with a promoter. These promoters ensure that the gene can only be produced
in the target area. Once several copies of these new promoter genes are created, these genes are
inserted to the egg of an animal to be implanted. Therefore, this animal and its offspring will
produce the wanted gene.
1.8 Benefits and Risks of GMO
In general, the end of genetic engineering is to create an improved variety of organism,

one that has desirable traits. The following advances in genetic engineering show how it can be
beneficial to the organism and to humans.
1. Plants which have become more resistant to pests can eliminate the use of potentially
hazardous pesticides.
2. GMOs cam yield higher crop yields and more nutritious food that also have better flavor
and longer shelf life.
3. GMO crops can be grown even in harsh environments, like the GM flood-tolerant rice,
which can save the farmers’ livelihood.
4. GMOs can be a cheap source of medicine. For example, transgenic tobaccos with
Hepatitis B virus surface antigens can induce immune responses to the disease.
Despite these beneficial effects however, there are a lot of questions regarding the
negative effects of GMO. While scientists have not yet found negative effects on health from GM
foods, more research must be done to find out the risks brought about by GM products.
Nonetheless, environmentalists are worried about the possible negative effects of genetic
engineering on the biodiversity of the environment.
1. Beneficial insects, such as bees and butterflies that help in pollination may be at risk of
becoming “unintended targets” o GM plants.
2. Introduced genes may cause the GMOs to become invasive or toxic to wildlife.
3. Since all organisms in a transgenic population have the same genome, a decrease in
genetic diversity could leave the crops vulnerable to new diseases.
SECTION: MODULE #: 8-9

Directions: You are a part of Greenpeace Organization tasked to conduct a survey on the
current uses of genetically modified organisms. Create a poster that shows a brief
information about genetic engineering—its benefits and negative effects on the environment,
health, and biodiversity.

I. TOPIC: How Animals Survive

 Digestive System
 Respiratory System
 Circulatory System
 Excretory System
 Endocrine System
 Nervous System
 Skeletal System
 Muscular System

 Describe the general and unique characteristics of the different organ systems in
representative animal (S11/12LT-IIIaj-21)
 Analyze and appreciate the functional relationships of the different organ systems in
ensuring animal survival (S11/12LT-IIIaj-25)

9. Know the structure function relationship in the various organ systems
10. Able to synthesize the various functions of the organ systems in the day-today activity
of an individual
11. Evaluate the benefits and risks of using GMOs.
Reference:
Raymond A. Baltazar, Ceazar Ryan U. Cuarto, Jigger P. Leonor, Ph.D., 2016, Conceptual
Science and Beyond Earth and Life Science (A Worktext for Senior High School), Brilliant
Creations Publishing, Inc.: Bonanza Plaza 2, Block 1, Lot 6, Hilltop Subdivision Greater Lagro,
Novaliches, Quezon City, pp. 102-120
Reproduction is the process by which organisms produce offspring’s; thereby allowing the
Animal cells need constant supply of nutrients such as water, oxygen, carbohydrates, lipids,
proteins, and vitamins. They must also eliminate waste products like carbon dioxide and nitrogen-
containing compounds.
In single-celled organism, exchange of materials occurs directly with the external
environment. However, multicellular animals cannot exchange materials this way. Instead, various
organ systems perform functions of exchange. The different parts and organs of each organ
systems play a very important role in the unique characteristic and function in keeping animals
alive.
This lesson will discuss the unique characteristics of the different organ systems of some
animals. It will also give concepts on how some animals from varied habitats differ in their ways of
exchanging gases from their body and environment. It will further illustrate the different digestive
systems of some animals and will give your idea on why some animals can digest food easily than
other animals.
Organ system is a group of organs that contribute to specific function to the body. The
heart for example is the main organ of the circulatory system. Are there other organs which help
the heart in carrying out the task for the function of the circulatory system? Can you name some of
them? Can you name other organ systems aside from the circulatory system?
Below is the list of the different organ systems of some representative animals. Each
system is made up of different parts or organs that perform different tasks to carry out a specific
function in ensuring the survival of animals. In the more advanced animals, there are usually 10
organ systems: integumentary (skin), skeletal, muscular, nervous, endocrine, digestive, respiratory,
circulatory, excretory (urinary), and reproductive.
The unique characteristic and functions of the different organ system
ORGAN SYSTEM FUNCTIONS
Circulatory System Transport’s nutrients, gases (oxygen and carbon dioxide),

hormones, and wastes throughout the body.
Digestive System Converts air, food, and water into building materials for living
tissue. Breaks down food, absorbs nutrients and eliminates
wastes.
Lymphatic System Destroys and removes invading microbes and viruses.
Removes fat and excess fluids from the blood
Muscular/Skeletal System Provides structure and mobility, and even controls the
movement of materials through some organs.
Nervous System Relays electrical signals, directs behavior and movement, and
helps control physiological processes such as digestion,
circulation, respiration, etc.
Reproductive/Endocrine Manufactures cells that create and support new life. Regulates
System hormones and relays chemical messages throughout the body.
Respiratory System Provides oxygen and gas exchange between the blood and the
environment.
Urinary System Filters wastes, toxins, excess water and nutrients from the
circulatory system
1.2 Digestive System
Food Getting, Digestion, and Absorption
Like plants, animals need nutrients to live; but unlike plants, they cannot make their own
food. To survive, animals must bring food to the body cells, through consumption. The digestive
system brings foods from outside the organism, digests them into simple nutrient molecules, and
absorbs the nutrients for distribution to all the cells in the body.
Invertebrates and vertebrates have different ways of digesting their food.
Invertebrate Digestive Systems
Invertebrate can be classified as those having gastrovascular cavities and those having
alimentary canals.
Platyhelminthes (flatworms) and cnidarians (corals, sea anemones, jelly fish) digest their
food through a gastrovascular cavity- a tube or cavity with only on opening that serves as both
mouth and anus. Ingested materials enter the mouth and pass through the cavity, where digestive
enzymes are secreted to break down the food. The cells lining the cavity engulf the food particles.
Some invertebrates, such as earthworms and insects, have more complex digestive
systems. Like vertebrates, they have an alimentary canal, the pathway which receives food through
the mouth on one end and eliminates wastes through the anus on another. The alimentary canal of
the invertebrates consists of the mouth, esophagus, crop, gizzard, intestines, and anus.
Vertebrate Digestive Systems
Animal digestion among the vertebrates begins in the mouth, the moves through the
pharynx, into the esophagus, into the stomach, and then into the intestines. Nutrients are absorbed
in the small intestine, and wastes are prepared for elimination in the large intestine.
There are four (4) types of digestive systems among the vertebrates namely: monogastric,
avian, ruminant, and pseudo-ruminant.
https://www.youtube.com/watch?v=tYHtuo0pdVg
Monogastric Digestive System
The monogastric digestive system- like those

of humans (omnivore), cats (carnivore), and rabbits
(herbivore)- consists of a single stomach chamber.
In this type of digestion, both physical and chemical
digestion of food begins in the mouth. The first step in
obtaining nutrition is ingestion, a process was food
is taken in through the mouth and broken down by the
teeth and saliva. The breaking down of food in the
mouth is called mastication (chewing). For the
nutrients (carbohydrates, lipids, vitamins) to be
absorbs, food must go down the esophagus through
peristalsis. Food then reaches the stomach and the
intestines, where it is further broken down Figure 1. The human digestive system
into acid chyme and undergoes absorption of is monogastric
nutrients. Undigested food enters the colon where water is reabsorbed into the body and
excess waste is eliminated through the anus.
Avian Digestive System
Birds do not have teeth, and therefore, do not

masticate their food. In anavian digestive
system, food enters through the mouth, then
the esophagus, and empties directly into the
first stomach- the crop, where the food is
stored and soaked. From the crop, food
enters the proventriculus, where gastric
juices are
secreted to digest the food. Then, it passes through the small and large intestines where
absorption happens. The undigested food becomes food Figure 2. The parts of an avian
pellets that are excreted as waste through the cloaca or are digestive system
sometimes regurgitated. Because most birds fly, they have
high metabolism which can keep their body weight low.
Ruminant Digestive System
A ruminant digestive system- like those of cows, sheep, and goats is polygastric,
which means that the stomach has multiple compartments: the rumen, reticulum,
omasum, and abomasum. Because the diet of ruminants consists largely of roughage or
fiber, their digestive system enables them to break down cellulose (the main component of
the rigid cell wall in plant cells). The rumen- the first and largest chamber- contains many
bacteria and microbes that promote fermentation and break down the food. The second
chamber is the reticulum, a small pouch that traps foreign materials which the ruminant
animal may have swallowed. The third chamber is the omasum, which grinds the food and
removes water from it. The fourth chamber- the abomasums- serves as the “true”
stomach in that it functions similarly as the stomach of monogastric animals. After passing
through the four chambers, the food finally reaches the small and large intestines for
absorption of nutrients and elimination of waste, respectively. A unique feature of this type
of digestive system is that it relies greatly on microorganisms for the digestion of roughage.
Figure 3. Parts of a ruminant digestive system
Pseudo-ruminant Digestive System
Pseudo-ruminants- like camels, horses, rabbits, and guinea pigs- are similar to
ruminants in that they eat a lot of roughage, fiber, forages, and grains. They are slightly
different from ruminant, however, in that their stomach has three chambers: reticulum,
omasum, and abomasum. Their digestive system also has an enlarge cecum where food
is fermented and digested. As in the ruminant, this type of digestive system also relies on
microbial support for digestion.
1.3 Respiratory System
Gas Exchange
The respiratory system consists of organs that allow gas exchange. It brings oxygen into
the body cells and gets rid of carbon dioxide, a cell waste product. Respiration occurs through the
respiratory organs of different animals, which include skin, gills, tracheal system, and lungs.
 Amphibians and earthworms

- use their skin (integument) to exchange gases between the external
environment and the circulatory system due to the network of capillaries that
lie below the skin.
Fish and Other Aquatic organisms

- use their gills to take up oxygen dissolved in the water and diffuse carbon
dioxide out of the bloodstream. When water passes over the gills, the
dissolved oxygen in the water rapidly diffuses across the gills into the
bloodstream.
 Insects
- Utilize a tracheal system that transports oxygen from the external environment
through openings called spiracles. Spiracles are small openings or tubes that
carry oxygen to the entire body of insects
 Mammals
- The main organs for gas exchange are the lungs. Air entering through the
nostrils is filtered by hairs, warmed, and moistened. The air then travels
through the pharynx which is common passageway for food and air; then
though the larynx which possesses vocal cords and functions as a voice box.
The epiglottis covers the larynx during swallowing. The air flow then enters
the cartilage-lined trachea that forks into two bronchi which further branch
into bronchioles that end in the alveoli. Alveoli are wrapped by capillaries for
gas exchange.
Air is drawn into and pushed out of the lungs by the alternate inhalation (inspiration) and
exhalation (expiration) of air is called breathing. During inhalation, air is pulled into the lungs by
the contraction of the diaphragm. The rib muscles pull the ribs upwards, which expand the rib cage.
The process of inhalation occurs due to an increase in the lung volume (diaphragm contraction and
chest wall expansion) resulting in a decrease in lung pressure in comparison to the atmosphere;
thus, air rushes in the airway. Exhalation occurs when the diaphragm and the rib muscles relax,
decreasing the volume of the thoracic cavity. The process of exhalation occurs due to the elastic
recoil of the lung tissue which causes a decrease in volume, resulting in increased pressure in
comparison to the atmosphere; thus, air rushes out of the airway. Gas is exchanged between the
alveoli and the pulmonary capillaries via diffusion. Gas molecules move from an area of high
concentration to an area of low concentration.
1.4 Circulatory System

Internal Transport System
Every organism exchange material with its environment. In most animals, transport
systems connect the organs of exchange with the bod cells. The circulatory system distributes
nutrients and oxygen to the body cells. It also collects carbon dioxide and other metabolic wastes
from the cells and brings them to their respective disposal sites. It consists of a pumping organ- the
heart – which pumps blood through the blood vessels. The circulatory systems of animals differ in
the number of heart chambers and the number of circuits through which the blood flows.
 Fishes
- have a single systematic circuit for blood, where the two-chambered heart
pumps the blood to the gills to be re-oxygenated (gill circulation), after which
the blood flows to the rest of the body and back to the heart.
 Amphibians, reptiles, birds, & mammals
- Blood flow is directed into two circuits: one through the lings and back to the
heart (pulmonary circulation) and the other throughout the rest of the body and
its organ, including the brain (systematic circulation).
Amphibians are unique in that they have a third circuit that brings deoxygenated blood to
the skin in order for gas exchange to occur. This is called pulmocutaneous circulation. The
number of heart chambers, atria, and ventricles, mitigates the amount of mixing oxygenated and
deoxygenated blood in the heart as more cambers usually mean more separation between the
systematic and pulmonary circuits. Warm-blooded animals require the more-efficient system of four
chambers that separate the oxygenated blood completely from the deoxygenated blood.
Gill capillaries Lung capillaries Lung capillaries

Figure 4. In fishes, blood flows in one direction from the two-chambered heart through the gills and
then to the rest of the body. Most reptiles have two circulatory routes; however, blood is only
oxygenated through the lungs. The heart is three chambered, but the ventricles are partially
separated so some mixing of oxygenated and deoxygenated blood occur, except in crocodiles and
birds. Mammals and birds have the most efficient heart with four chambers that separate the
oxygenated and deoxygenated blood; it pumps only oxygenated blood through the body and
deoxygenated blood out form the lungs.
1.5 Excretory System
Excretion
All organisms produce waste products form the chemical reactions that take place in their
bodies. The excretory system provides a mechanism for the elimination of various wastes from the
body. The wastes such as excess water and salts, carbon dioxide, and urea are removed from the
body by the organs of excretory system.
Excretion Process among Vertebrates
The kidneys are the main excretory organs of the body. It has two distinct regions namely,
an outer renal cortex and an inner renal medulla. They excrete most of the urea and excess water,
salt, and sugar as urine. Each kidney is supplied with blood by a renal artery and drained by a
renal vein. Urine exits each kidney through a duct called the ureter. Both ureters drain into a
common urinary bladder, and urine is expelled through the urethra.
The nephron is the functional unit of the kidney which consists of a single long tubule and
a ball of capillaries called the glomerulus. Filtration happens in the glomerulus which starts when
the blood pressure forces the fluid composed of small molecules (water, salt, glucose, amino acids,
ions, water, and urea) into the hollow interior of the Bowman’s capsule. This fluid is now called
filtrate. From the Bowman’s capsule, the filtrate passes through three regions of the nephron
namely, proximal tubule, loop of Henle and distal tube. Fluid from several nephrons flows into a
collecting duct: then, to the renal pelvis and ureter.
Reabsorption of ions, water, and nutrients takes place in the proximal tubule. Some toxic
materials and waste from the blood are secreted into the filtrate. These are then secreted, forming
urine. The filtered blood flows into the renal vein, while the remaining filtrate passes into a
collecting duct. The collecting duct carries filtrate or urine through the medulla to the renal pelvis.
Water is lost as well as some salt and urea, and the filtrate becomes more concentrated.
Urine passes through the ureters, tubes that carry the urine from the kidney to the urinary
bladder, a hollow muscular sac that stores urine. Muscular contractions of the bladder force urine
out if the body as it passes through a tube called urethra.
Excretion Systems among Invertebrates
In some animals, flame cells, nephridia, and malpighian tubules remove the waste from the
bodies through filtration in a manner like a vertebrate kidney.
Flame Cells of Planaria
Planaria are flatworms that live in fresh water. Their excretory system consists of two
tubules connected to a highly branched duct system that leads to pores located all along the sides
of the body. The filtrate is secreted through these pores. The cells in the tubules are called flame
cells (or protonephridia) because they have a cluster of cilia that looks like a flickering flame when
viewed under the microscope.
Figure 5. The flame cell in planaria
functions like a kidney, removing waste
materials through filtration
Nephridia of Worms
Nephridia are more evolved than flame cells because they can reabsorb useful
metabolites before excretion of waste. A pair of nephridia is present on each segment of the
earthworm. They are similar to flame cells in that they have tubules with cilia and function like a
kidney to remove wastes.
Figure 6. The nephridium is a ciliated tubule

that absorbs fluids in the cell to remove waste.
Malpighian Tubules of Insects
The malpighian tubules remove wastes from insects by producing urine and solid
nitrogenous wastes, which are then excreted from the body.
Figure 7. In insects, urine is produced by tubular secretion mechanisms of the cells lining the
malpighian tubules
1.6 Endocrine System
Hormones are chemical substances produced by an endocrine gland. They are

transported into the circulatory system to target organs where they exert their functions.
The endocrine system secretes hormones that coordinate slower but longer-acting
responses including reproduction, development, energy metabolism, growth, and behavior.
Hormones help the various parts of the body to respond, develop and work together smoothly.
Hormones are produced in small amounts by specific glands. A gland is a cell, tissue, or an
organ that secretes chemical substances. There are two types of glands: endocrine and exocrine
gland. Endocrine glands are ductless and secrete hormones directly into the bloodstream.
Exocrine glands have ducts and secrete substances onto body surfaces or into body cavities (for
example, sweat glands have ducts for carrying sweat out of the body).
Figure 8. The endocrine glands of a dog. As in

humans, they consist of a group of tissues that
release hormones into the bloodstream to travel to
other parts of the body. Most endocrine tissues are
glands (such as the thyroid gland) that release
hormones directly into small blood vessels within
and around the tissue.
The endocrine system adjusts the number of hormones being made or released. Feedback
mechanisms detect the amount of hormone in circulation. In high levels of hormone stimulate the
production of more hormones, the regulation is called positive feedback. Oxytocin includes uterine
contractions and the release of milk. Suckling sends a message to the hypothalamus via the
nervous system to release oxytocin, which further stimulates the milk glands. In a negative
feedback, it counteracts the production of hormone in one direction. Insulin and glucagon are
antagonistic hormones that help maintain glucose homeostasis. After hormones have performed
their functions, they are eventually destroyed by the liver and excreted by the kidneys.
Major Endocrine Glands, their Hormones, and Functions
Gland Hormone Function Regulated by

Hypothalamus Hormones released from the posterior pituitary and hormones that
regulate the anterior pituitary (see below)
Posterior pituitary Oxytocin Stimulate contraction Nervous system
gland (releases of the uterus and
neurohormones made mammary gland cells Water/salt balance
in hypothalamus)
Antidiuretic hormone Promotes retention of
water by the kidneys
Anterior pituitary Growth hormone Stimulates growth Hypothalamic
hormones
Prolactin Stimulates milk
production Hypothalamic
Follicle-stimulating hormones
hormone (FSH) Stimulates production
of ova and sperms Hypothalamic
Luteinizing hormone hormones
(LH) Stimulates ovaries
and testes
Hypothalamic
Thyroid –stimulating Stimulates thyroid hormones
hormone (TSH) gland
Adrenocorticotropic Hypothalamic
hormone (ACTH) Stimulates adrenal hormones
cortex to secrete
glucocorticoids
Hypothalamic
hormones
Thyroid gland Triiodothyronine (T2) Stimulate and TCH

and thyroxine (T4) maintain metabolic
processes
Calcitonin Calcium in blood
Lowers blood calcium
level
Parathyroid glands Parathyroid hormone Raises blood calcium Calcium in blood
(PTH) level
Pancreas Insulin Lowers blood glucose Glucose in blood
Glucagon Raises blood glucose Glucose in blood
Adrenal glands Epinephrine and Raises blood glucose; Nervous system

norepinephrine increase metabolic
activities; constrict
blood vessels
Adrenal medulla Glucocorticoids ACTH K+ in blood
Raises blood glucose
Adrenal cortex Mineralocorticoids level
Promote reabsorption
of Na+ and excretion
of K+ in the kidneys
Gonads
Testes Androgens Support sperm FSH and LH

formation; promote
development of male
secondary sex
characteristic
Ovaries Estrogens FSH and LH
Stimulate uterine
lining growth; promote
development of
female secondary
characteristics
Progestins FSH and LH
Promote uterine lining
growth
Pineal gland Melatonin Involved in biological Light/dark cycles
rhythms
1.7 Nervous System
The nervous system enables the body to respond quickly to changes in the environment
by gathering information, transmitting, and processing information to determine the best response,
and sending information to muscles, glands, and organs so they can respond correctly.
The nervous system includes two main types of cells: neurons, which conduct messages;
and supporting cells (glia), which provide structural reinforcement as well as protect, insulate, and
assist the neuron.
The nervous system of invertebrates varies in structure and complexity, as shown I figure
4.9. Unlike in vertebrates, the nervous system of some invertebrates does not have distinct central
and peripheral systems, but response to the environment is still possible.
Figure 9. Nervous systems of invertebrates vary in structure and complexity. Some invertebrates,
like cnidarians and echinoderms, do not have a brain. In (a) cnidarians, nerve cells form a
decentralized nerve net. In (b) echinoderms, nerve cells are bundled into fibers called nerves. In
some invertebrates exhibiting bilateral symmetry, such as planarians and arthropods, a brain and a
nerve cord are present. (c) Planarians have two longitudinal nerve cords with neurons clustered
into an anterior brain. (d) Arthropods have clusters of nerve cell bodies, called peripheral ganglia,
located alon the ventral nerve cord that is connected to the central ganglia (brain). (e) Mollusks
have a complex nervous system that consists of a brain, millions of neurons, and giant axons.
Vertebrates Nervous System
Vertebrates have a complex nervous system made up of central nervous system (CNS)
and peripheral nervous system (PNS).
The central nervous system (CNS) consists of the brain and spinal cord. It is responsible
for integration of sensory input and association of stimuli with appropriate motor output. The CNS
processes the information and responds by sending nerve impulses to the motor output. The CNS
processes the information and responds by sending nerve impulses to the motor nerves of the
peripheral nervous system.
The peripheral nervous system (PNS) is the link between on the CNS (brain and spinal
cord) to the rest of the body. It consists of the network of nerves, called neurons, extending into
different parts of the body that carry sensory input to the CNS and motor output away from the
CNS.
Neurons are specialized cells that transmit chemical and electrical signals from one
location in the body to another. They have a large cell body (soma). The cell body consists most of
the cytoplasm, the nucleus, and other organelles. Dendrites convey signals to the cell body. Axons
conduct impulses away from the cell body. Vertebrate axons in PNS are wrapped in concentric
layers of Schwann cells, which form an insulting myelin sheath.
In the CNS, the myelin sheath is formed by oligodendrocytes. Axons extend from the
axon hillock (where impulses are generated) to many branches, which are tipped with synaptic
terminals that release neurotransmitters. Synapse is a gap between a synaptic terminal and a
target cell- either dendrites of another neuron or an effector cell. Neurotransmitters are chemicals
that cross the synapse to relay the impulse.
Figure 10. The structure of a typical neuron includes four

main components: dendrites, cell body (or soma), axon, and
axon terminal. The axon terminal refers to the small branches
of the axon that form the synapses, or connections with other
cells.
There are three major classes of neurons, which are as follows:
1. Sensory neurons or afferent neurons receive stimuli from sense organs where most receptors
are located. The sensory neuron transmits impulses to other sensory neurons until the impulse
reaches the interneuron.
2. Interneurons or connector neutrons integrate sensory input and motor output. They are found in
the spinal cord and in the brain. Interneuron determines what response should be generated by
passing the impulse to motor neurons.
3. Motor neurons or different neurons convey impulses to effector cells. When a motor neuron
receives a signal from the interneuron, the motor neurons work to stimulate an action. When
effector cells are stimulated, they generate reactions.
In the PNS, afferent neurons transmit information to the CNS and efferent neurons
transmit information away from the CNS. The PNS has two functional components: the motor
system and the automatic nervous system. The motor system carries signals to skeletal muscles
and is voluntary. The autonomic nervous system regulates the internal environment in an
involuntary manner. The PNS autonomic nervous system has sympathetic, parasympathetic, and
enteric divisions.
The sympathetic and parasympathetic divisions have antagonistic effects on target

organs. The parasympathetic division enhances activities that gain and conserve energy, while the
sympathetic division increases energy expenditures. The parasympathetic division promotes a
return to “rest and digest”. The sympathetic division correlates with the “fight-or-flight” response.
The enteric division controls activity of the digestive tract, pancreas, and gallbladder.
1.8 Skeletal Systems
Animals, whether vertebrate or invertebrate, have evolved skeletal and muscular

systems that give them form and enable them to move.
In animals, a skeletal system is necessary to support the body, protect internal organs,
and allow for the movement of an organism. There are three different skeleton designs that provide
these functions: hydrostatic skeleton, exoskeleton, and endoskeleton.
A hydrostatic skeleton or hydro skeleton is a structure found in many ectothermic

organisms and soft-bodied animals consisting of the coelom, a fluid-filled cavity, surrounded by
muscles. The skeleton of a starfish is an example of hydrostatic skeleton.
An exoskeleton is the external skeleton that supports and protects an animal’s body, in
contrast to the internal skeleton (endoskeleton) of a human. In usage, some of the larger kinds of
exoskeletons are known as shells. Animals with an exoskeleton include insects such as
grasshoppers and cockroaches, crustaceans such as crabs and scorpions, and mollusks such as
snails and clams. The muscles attached to the skeleton of such animals allow the animal to move.
An endoskeleton is a structure that holds an animal from inside. An endoskeleton allows

the body to move and give the body structure and shape.
The human skeleton is an endoskeleton that consists of 206 bones in the adult, as well as
a network of tendons, ligaments, and cartilage that connects them. The skeletal system performs
vital functions, such as support, movement, protection, blood cell production, calcium storage, and
endocrine regulation.
The human skeleton is the internal framework of the body. It has two distinct parts: axial
and appendicular. The axial part has a total of 80 bones which consists of the vertebral column, the
rib cage, and the skull. The appendicular part has a total of 126 bones which consists of the
pectoral girdles, the upper limbs, the pelvic girdle, and the lower limbs.
In humans and vertebrates, bones are connected to one another by joints. The end of each
bone is covered by a cartilage which ensures that the bones will not scratch or bump against each
other. Bones are also held by together by strong stretchy bands called ligaments which prevent the
joints from moving too fair in one direction. Bones are also connected to the muscles by a dense
connective tissue called tendons.
1.9 Muscular Systems
Bones by themselves cannot move the body. In most animals, muscles are needed to
bring about movement. Movement is brought about by the contraction and relaxation of muscles.
Muscles are organs made up of muscle fibers.
In vertebrates, muscle fibers shorten when a muscle contract. Each muscle fiber consists of
threadlike, small cylindrical structures called myofibrils. Myofilaments are the chains of actin (thin
protein filaments) and myosin (thick protein filaments) that pack a muscle fiber.
Actin and myosin are arranged alternately and known collectively as sarcomere. The
sarcomeres are separated from each other by an area of dense matter known as the Z line. During
contraction, actin and myosin slide past each other until the point where their ends almost touch
each other. When the muscles are relaxed, the ends of the actin and myosin overlap slightly but do
not touch each other. It is this sliding action of the actin and myosin that causes the muscles to
move.
There are their main types of vertebrate muscles: skeletal, smooth, and cardiac. Skeletal
muscles are striped and voluntary, which means we can control them by thinking. Smooth muscles
are involuntary which are responsible for the pumping of the heart, and they never stop working.
Activity 1: Who is Responsible?
Direction: Which organ system is the most responsible in the following situations? Write on the space
provided before each item the letter that represents the organ system of your choice.
MS muscular/skeletal D digestive L lymphatic U/E

urinary/excretory
R respiratory N nervous C circulatory RE Reproductive
______1. You studied well last night for today’s first grading examination.
______2. You have eaten a good breakfast for energy source.
______3. You went to the bathroom since you drank a lot of water. You would not want to go out from
the room during the exam.
______4. You went to the bathroom since you drank a lot of water. You would not want to go out from
the room during the exam.
______5. You walked hurriedly so you will not be late. You are catching your breath.
______6. You were out of balance and fell on your knee. But you managed to get up quickly.
______7. You were thankful. You have strong bones.
______8. You are now in the classroom. You are excited and your chest is beating fast. But you are
confident because you are ready.
Activity 2: Where do you belong?

The table below is divided into four, according to the four basic types of digestive system. Group
the given list of animals according to the type of their digestive system. The first ones are your
examples.
Chicken cow humans pig
bird
cat hog sheep dog
Duck
rabbit hamster earthworm horses
goat
MONOGASTRIC AVIAN RUMINANT PSEUDO- RUMINANT

Activity 3: Slogan Making
Choose one organ system. In a 1/8 illustration board, make a slogan for your chosen organ
system conveying a message of its importance. You may use any coloring materials. Be creative.
RUBRICS
Category 4 3 2 1
Presentation The slogan The slogan The slogan The slogan does
clearly clearly indirectly not sufficiently
communicates communicates communicates communicate
the main idea some of the the idea and any idea that
and strongly important ideas hardly conveys a conveys a
convey a and slightly message of message of
message of conveys a importance importance
importance message of
importance
Creativity All the Most of the The graphics The graphics
and graphics used graphics used on were made by the we are not made
Originality on the slogan the slogan student but were by the student.
reflect an reflect student copied from the
exceptional ingenuity in them designs or ideas
degree of creation. of others.
student ingenuity
in their creation.
Accuracy All graphics in Most graphics in Some graphics in The graphics in
and the slogan is the slogan is the slogan is the slogan is
relevance accurate and accurate and accurate and neither accurate
related to the related to the related to the nor related to
topic. topic. topic. the topic.
Required The slogan All required Few required Required
Element includes all elements are elements are elements are
required included. included. missing.
elements as well
as additional
information.

I. TOPIC: The Process of Evolution

 Darwin’s On the Origin of Species
 Evidence of Evolution
 Mechanisms of Evolution
 Models of Speciation
T

 Explain how populations of organisms have changed and continue to change over time
showing patterns of descent with modification from common ancestors to produce the
organismal diversity observed today. (S11/12LT-IVfg-26)
 Describe how the present system of classification of organisms is based on evolutionary
relationship. (S11/12LT-IVfg-27)

 Differentiate Lamarckian Evolution and Darwinian Evolution through illustrations or
models
 Understand Darwin’s Theory of Evolution
 Clarify Misconceptions about the Theory of Evolution
 Explain how organisms are classified based on evolutionary relationships
Reference:
Raymond A. Baltazar, Ceazar Ryan U. Cuarto, Jigger P. Leonor, Ph.D., 2016, Conceptual
Science and Beyond Earth and Life Science (A Worktext for Senior High School), Brilliant
Creations Publishing, Inc.: Bonanza Plaza 2, Block 1, Lot 6, Hilltop Subdivision Greater Lagro,
Novaliches, Quezon City, pp. 140-149
Evolution concerns the change in a population of organisms over time. It is a process which,
allows only the organisms that are better adapted to their changing environment to continuously live
and reproduce for the perpetuation of life for billions of years. Charles Darwin emphasized “descent
with modification”, to explain life’s unity and diversity. He also believed that natural selection provided a
mechanism for this evolutionary change.
In this chapter, you will learn the pieces of evidence that support the occurrence of evolution,
such as fossil records, comparative anatomy and embryology, biogeography, and biochemical makeup
of organisms. You will also investigate how populations of organisms have evolved and continued to
change to produce the diversity of life today. The need to classify organisms develops from the strong
possibility to trace the evolutionary origin of organisms. It requires a detailed exploration of the past to
appreciate “unity despite diversity”.
1.1 Darwin’s On the Origin of Species
Evolution refers to the life processes that have transformed on Earth from its earliest forms to
the enormous diversity that characterizes it today. It remains a constant process if organisms are being
born, dying, and competing for what they need to survive and reproduce.
Charles Darwin believed that life had changed gradually over time and continued to change.
He also believed that organisms were related, and they changed to be better adapted to their
environments. On November 24, 1859, he published On the Origin of Species, where he discussed
major biological issues, such as why there are so many kinds of organisms, their origins and
relationships, similarities and differences, geographic distribution, and adaptations to their environment.
Darwin cited two major points in this book, “On the Origin of Species.”
1. Organisms present today descended from ancestral species that were different from the
modern species. Descent with modification explains life’s unity and diversity.
2. Natural selection provided a mechanism for this evolutionary change.
His work “On the Origin of Species” introduced two ground-breaking ideas in the study of life:
evolution and natural selection as its mechanism.
1.1.1 Descent with Modification
Darwin scarcely used the word “evolution” in On the Origin of Species. Instead, he used the
phrase descent with modification.
All the organisms are related through descent from a common ancestor that lived in the remote
past. Over evolutionary time, the descendants of that common ancestor have accumulated diverse
modifications, or adaptations, that allow them to survive and reproduce in specific habitats.
An example of how descent with modification affects species over millions of years is shown
below. This shows a clade depicting elephant evolution over time.
Figure 1. Darwin proposed that

organisms are relate by being
descendants of a common ancestor,
with modifications among the
descendants. Based on fossil
evidence, this evolutionary tree
reveals that manatees and hyraxes
are the elephant’s closest living
relatives.
1.1.2 Natural Selection
Darwin’s theory of natural selection is most known as the “survival of the fittest”. He
hypothesized that there is a constant struggle for existence, and only certain members of a population
survive and reproduce in each generation.
Darwin perceived adaptation to the environment and the origin of new species as closely
related processes. He believed that organisms, even of the same species, were all different and that
those variations helped them adapt and survive in their environment and reproduce more offspring.
Other organisms that were not so well adapted died out.
To explain natural selection, Darwin used the giraffe as an example.
Some giraffes with chance mutation produced longer necks that enabled them to avoid
competition with other animals for food. This adaptive trait enabled them to survive and reproduce. The
short-necked giraffes failed to survive due to competition that led to their extinction.
Natural Selection is the process by which organisms with an advantage reproduce more than
others of their kind. Some aspects of the environment act as a selective agent and choose the
members of the population with the advantageous trait to reproduce more than the other members.
Natural selection has these essential components.
1. The members of a population have inheritable variations.

Survival in the struggle for existence is not random but depends in part on inherited
traits. Those individuals whose inherited traits are best suited for survival and reproduction in
their environment are likely to leave more offspring than less fit individuals.
2. A population can produce more offspring than the environment can support
Production of more individuals than the environment can support leads to a struggle
for existence among the individuals of a population, with only a fraction of the offspring
surviving each generation.
3. Only certain members of the population survive and reproduce.
This unequal ability of individuals to survive and reproduce will lead to a gradual
change in a population, which favorable characteristics accumulating over generations.
4. Natural selection results in a population adapted to the local environment.

The individuals best adapted to their environment will survive and reproduce.
Evolution consists of changes in a population over time due to the accumulation of
inherited differences. Evolution explains the unity and diversity of organisms. “Unity” suggests
that organisms share common characteristics because they share common ancestry.
“Diversity” develops because each type of organism (each species) is adapted to the varied
environment in the biosphere.
1.2 Evidence of Evolution
Darwin used several lines of evidence to support his principle of common descent, an
evolutionary change. These include fossils and anatomical and embryological evidence. Recent
discoveries, including those form molecular biology, lend support to his evolutionary view of life.
Fossils
Fossils are evidence of usually extinct that have been preserved in the Earth’s crust. Most
fossils are formed when the hard parts of an organism become buried in sedimentary rocks.
Paleontologists have discovered fossils of many such transitional forms that link ancient
organisms to modern species. For example, fossil evidence document the origin of birds from one
branch of dinosaurs.
Figure 2. The Fossil of Archaeopteryx lithographica is an

intermediate between the birds that we see flying and he
predatory dinosaurs like Deinonychus. Unlike all living birds,
the Archaeopteryx had a full set of teeth, a long, bony tail,
and three claws on the wing which could have been used to
grasp prey or trees. However, its feathers, wings, and
reduced fingers are all characteristics of modern birds.
The Archaeopteryx lithographica fossil discovered in the early 1860s is an intermediary
between reptiles and birds. Like birds, it had feathers along its arms and tail, but unlike living birds, it
also had teeth and a long bony tail. Furthermore, many of the bones in Archaeopteryx’s hands,
shoulder girdles, pelvis, and feet were distinct, not fused and reduced as they are in living birds.
Recent discoveries include fossilized whales that link these aquatic mammals to their terrestrial
ancestors. Ambulocetus natans was about the size of a large sea lion, with broad, webbed feet on its
forelimbs and hind limbs that enabled it to walk and swim. It also had tiny hoofs on its toes and the
primitive skull and teeth or early whales. The name comes from the Latin words “ambulare” (to walk),
“cetus” (whale), and “natans” (swimming) and means “a walking and swimming whale”.
Figure 3. Fossil remains of the ancestor of a modern toothed whale
Anatomical Evidence
Anatomic similarities exist between fossils and living organisms. Anatomical similarities
among species grouped in the same taxonomic category reflect their common descent. The skeletal
components of maintain forelimbs are a good example. See the illustration below.
Figure 4. All vertebrate forelimbs contain the

same bones: humerus, radius, ulna, carpals,
metacarpals, and phalanges. These
forelimbs have been modified for very
different uses by different vertebrate groups.
The fact that these different limbs contain the
same bones is a very strong indicator of
evolutionary relationship.
Homology is similarity resulting from common ancestry. Homologous structures are anatomical
similarities because they are inherited from a common ancestor. The presence of homology is a proof
that organisms are closely related.
Some homologous structures are vestigial organs. Vestigial structures are remnants of pelvic
and leg bones in snakes show descent from a walking ancestor but have no function in the snake.
Embryological Evidence
Closely related organisms go through similar stages in their embryonic development. At

some time during development, all vertebrates have a post anal tail and a pair of pharyngeal pouches.
Figure 5. As the body segments form, bird

embryo and human embryo are almost
identical. Notice the post-anal tail and
ancestral gill slits, which in mammals later
developed as parts of the ear and the
pharynx.
Vertebrate embryos (fishes, amphibians, reptiles, birds, mammals) go through an embryonic
stage in which they possess gill slits on the sides of their throats. These embryonic structures develop
into very different, but still homologous, adult structures, such as gills of fish or the Eustacian tubes that
connect the middle ear with the throat in mammals.
Terrestrial vertebrates develop and modify pharyngeal pouches that have lost their original
function because terrestrial vertebrates can trace their ancestry to amphibians and then, to fishes.
Biogeographic Evidence
Biogeography is the study of the geographical distribution of plants and animals throughout
the world. Different life forms in different regions had come from ancestors in those regions and had
adapted over time to the conditions in the place.
Species tend to be more closely related to other species form the same area than to other
species that live in different areas. When Australia and South America were united in a single
continent, an “original” marsupial lived there, and then as the two continents separated, the marsupials
on each continent gradually evolved into different species to better adapt to their new environments.
To take another example, both cactuses and euphorbia are adapted to a hot, dry
environment. Cactuses grown in North American deserts and euphorbia grow in African deserts. This
supports the hypothesis that some plants evolve only on their respective continents. Evolution is
influenced by the mix of plants and animals in a particular continent.
Biochemical Evidence
An organism’s hereditary background is reflected in its genes and their protein products. Two
species considered to be closely related by other criteria should have greater similarity in their DNA
and proteins than two unrelated organisms of the same species.
Molecular taxonomists use a variety of modern techniques to measure the degree of similarity
among DNA nucleotide sequences of different species.
1. The closer two species are taxonomically, the higher the percentage of common DNA. This evidence
supports common descent.
2. Common descent is also supported by the fact that closely related species also have proteins of
similar amino acid sequence (resulting from inherited genes).
3. If two species have many genes and proteins with sequences of monomers that match closely, the
sequences must have been copied from a common ancestor.
1.3 Mechanisms of Evolution
How does an entirely new species evolve and continue to change over time to produce the
diversity of organisms observed today?
Natural selection acts on individuals, but only populations evolve. Recall the difference
between species and population. Species refers to a group of populations whose individuals have the
potential to interbreed and produce fertile offspring in nature. A population is a localized group of
organisms which belong to the same species. Population is the functional unit of a species that can
evolve or give rise to a new species.
Speciation is the term used to describe how a new species evolves from an older one. A new
species is not able to reproduce with members of the original population.
The following are factors that can lead to speciation.
Mutation.
A mutation is a change in the hereditary material. It may be a change in the structure of a
gene- that is, in the sequence of nitrogen bases of an organism’s DNA- or it may be a change in the
structure or number of chromosomes. Only mutations that take place in gametes, or sex cells, are
passed on to the next generation. It is the ultimate source of new traits in a population. A mutation may
result in the change in appearance or a characteristic of a population.
Natural Selection
The theory of natural selection was Darwin’s explanation of how evolution happens.
Individuals in a population vary in their heritable traits. Those with traits better suited to the
environment tend to produce more offspring than those with traits that are less well suited. The genes
of the more fit become more numerous in the subsequent generations, and the overall appearance of
the population changes.
Genetic Drift
Genetic drift refers to the changes in the gene pool of a small population due to chance. The
smaller the population, the greater will be the impact of the genetic drift. This is because there are
fewer individuals, and the gene pool is smaller. Genetic drift can cause big losses of genetic variation
for small populations.
The bottleneck effect or population bottleneck is a sudden reduction in population size due
to a change in the environment, such as a natural disaster, habitat destruction, or hunting a species to
near extinction. When the size of the population is reduced so quickly, many alleles are lost, and the
genetic variation of the population decreases.
The founder effect is observed when a few individuals in a population colonize a new location
that is separate from the old population. This also greatly reduces the population size, as well as the
genetic variability of the population.
Migration
Gene flow, or gene migration, occurs when breeding members of a population leave a
population or when new members enter a population. Gene migration can introduce new alleles into
populations.
Humans today migrate much more freely than in the past, and gene flow has become an
important agent of evolutionary change in human populations that were previously isolated. However,
continual gene flow tends to reduce differences between populations.
Isolation
Isolation occurs when some members of species suddenly become separated from the rest of
the species. For instance, a mountain range prevents two types of goats from mating, causing the gene
pool to become less varied. This geographical barrier prevents interbreeding among the individuals of
the two populations.
Separate groups of organisms belonging to the same species may adapt in different ways to
better exploit diverse environments or resources. They also may evolve varied characteristics for
attracting mates. Over time, these groups or populations may become so different that they can no
longer breed together—separate species are formed. Several generations must happen, and those
genetic differences must accumulate to prevent reproductive success which later could lead to
development of new species.
1.4 Models of Speciation
In allopatric speciation, an ancestral population is geographically isolated result in in the

evolution of separate species largely due to genetic drift. The additive effect of differences due to
genetic drift can eventually result in behavioral isolation (refusal to mate) if the two groups were to meet
again in the future. If they refuse to interbreed, they would be considered separate species.
Sympatric speciation involves speciation without a geographic barrier. One example of

sympatric speciation is polyploidy, found more often in plants. Polyploidy occurs when a failure of
meiosis increases the number of chromosomes sets to 3n or more. This means that the organism has
more chromosomes than other individuals of the same species. At this point, the two “cousin” species
can no longer mate with each other. The polyploidy organism evolves, eventually leading to become a
separate species.
1.5 Taxonomy
Taxonomy is the branch of biology that deals with identifying, naming, and classifying organisms.
One goal of taxonomy is to determine the evolutionary history of organisms and the development of
their present forms. Phylogeny is the evolutionary history of a species or group of related species.
In the 18th century, Carolus Linnaeus published a system of taxonomy based in resemblances.
Linnaeus introduced a system for grouping species in increasingly broad categories. The
taxonomic groups are classified into domain: kingdom, phylum, class, order, family, genus, and
species.
Kingdom Animals
Organisms able to move on their own
Phylum Chordates
Animals with a backbone
Class Mammals
Chordates with fur or hair and mammary glands
Order Primates
Mammals with collar bones and grasping fingers
Family Hominids
Primates with relatively flat faces and here-dimensional vision
Genus Homo
Hominids with upright posture and large brains
Species Homo sapiens
Members of the genus Homo with a high forehead and thin skull bones
Figure 6. Hierarchical system of classification of organisms. The major categories, or taxa (singular:
taxon), are given one of several standard taxonomic ranks to indicate the levels of similarities between
all the members of the group. The system has been considerably expanded since Linnaeus includes
seven mandatory ranks in increasing level of similarities: kingdom, phylum, class, order, family, genus,
and species. All species described must belong to at least seven taxa, one at each the mandatory
level.
The evolutionary history of a group of organisms is represented by an evolutionary tree, a diagram that
indicates common ancestor.
Figure 7. Phylogenetic tree

of Order Carnivora provides
patterns of descent which
shows similar characteristics
in closely related species.
Animals belonging to the
same family share more
similar characteristics than
those belonging to different
families.
A species is most closely related to other species in the same genus, then genera in the same
family, and so forth, from order to class to phylum to kingdom. Two species that are closely related
share a more recent common ancestor with each other than with members of other taxa (any level of
hierarchy).
All the animals are related because we can trace their ancestry back to the same order. The
animals in the order Carnivora can be recognized by their enlarged fourth meat and tendon. Unlike
members of the family Canidae, family Felidae have a short rostrum and tooth row, which increases
bite force.
Phylogenetic trees do not show patterns of descent. It does not indicate when species evolved
or how much genetic change occurred in a lineage. Phylogeny provides important information about
similar characteristics in closely related species.
Activity: Search Me!
Research on the animals that are called “living fossils”. Explain how they provide further
understanding to the evolutionary history of organisms. Print it in a short bond paper. (30 pts.)

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What are the major categories in taxonomy and how are organisms classified?

What are the major categories in taxonomy and how are organisms classified?

EARTH AND

Mr. Bern E. Alvis

SUBJECT: Earth and Life Sciences DATE:

I. TOPIC: Universe and the Solar System

II. LEARNING COMPETENCY

The learner should be able to:

 At the end of the lesson, the student is expected to:

REFERENCES Raymond A. Baltazar, Ceazar Ryan U. Cuarto, Jigger P. Leonor, Ph.D.,

Gloria G. Salandanan, Ph.D., Ruben E. Faltado III, Ph.D., Merle B. Lopez,

V. GEAR UP YOUR MIND

Hymn of Creation of Rigveda

Philolaus (470-385 B.C.)

Aristotle (384-322 B.C.) ARISTOTLE

HELIOCENTRIC MODEL GEOCENTRIC MODEL

1.1.1 Structure, Composition, and Age

1.1.3 Evidence of the Big Bang Theory

1.2 Overview about Solar System

1.2.1 How did the Solar System Form?

1.2.2 Origin of the Solar System

1.3 Earth: A Habitable Planet

1.3.1 Earth as a System and its Subsystems

1.4 The Internal Structure of the Earth

Layers of the Earth

1.5 What Makes Up the Crust of the Earth?

2 Type of Igneous Rocks

a. Foliated metamorphic rocks- have layered or banded appearance caused by exposure

1.5.2 Rock Cycle

VI. BOOST UP YOUR LEARNING

Activity 1.1: A Model of an Expanding Universe

IV. Data and Observations:

Dots Distance from Distance from the dot Change of Factor by

SUBJECT: Earth and Life Sciences DATE:

I. TOPIC: Earth Materials and Processes

II. LEARNING COMPETENCY

The learner should be able to:

At the end of the lesson, the student is expected to:

REFERENCES Raymond A. Baltazar, Ceazar Ryan U. Cuarto, Jigger P. Leonor, Ph.D.,

Gloria G. Salandanan, Ph.D., Ruben E. Faltado III, Ph.D., Merle B. Lopez,

V. GEAR UP YOUR MIND

1.1 Rock Classifications

Petrology – study of rocks

Three (3) Types of Rocks

Magma vs. Lava

Two (2) Basic Types of Igneous Rocks

Intrusive or plutonic igneous rocks

Extrusive or volcanic igneous rocks

Texture Description Example

Three (3) Basic Types of Sedimentary

Clastic Sedimentary Rocks

Chemical Sedimentary Rocks

Organic Sedimentary Rocks

Two (2) Types of Metamorphic

Foliated metamorphic rocks

1.1.2 Rock Cycle