SHS

General Biology 2
Quarter 4: Week 2 – Module 1B
Processes in Plants and Animals
(Gas Exchange and Transport/Circulation)
General Biology 2
Grade 11/12 Quarter 4: Week 2 Module 1B: Processes in Plants and
Animals (Gas Exchange and Transport/Circulation)
First Edition, 2021
Copyright © 2021
La Union Schools Division
Region I

All rights reserved. No part of this module may be reproduced in any form
without written permission from the copyright owners.

Development Team of the Module

Author: Emilia V. Vizcarra, MT-I

Editor: SDO La Union, Learning Resource Quality Assurance Team

Illustrator: Ernesto F. Ramos Jr., P II

Management Team:

AttY. Donato D. Balderas, Jr.

Schools Division Superintendent

Vivian Luz S. Pagatpatan, Ph.D

Assistant Schools Division Superintendent

German E. Flora, Ph.D, CID Chief

Virgilio C. Boado, Ph.D, EPS in Charge of LRMS

Rominel S. Sobremonte, Ed.D, EPS in Charge of Science

Michael Jason D. Morales, PDO II

Claire P. Toluyen, Librarian II
 Target

The existence of life is primarily based on certain functions and processes on

the planet Earth. There are many fundamental essential processes that are required
for an individual to remain healthy and to ensure the proper functioning of the organ
systems of the body. For survival, they are necessary. These important basic
operations performed by an organism are called processes of life.

. In your previous lessons, you learned about reproduction, development and

nutrition. These are essential life processes that are vital for almost all forms of life
on earth to survive.

This module will provide you with concepts and activities that will help you
understand gas exchange and transport or circulation in plants and animals.

After going through this module, you are expected to:

Compare and contrast the following processes in plants and animals:

reproduction, development, nutrition, gas exchange, transport/ circulation,
regulation of body fluids, chemical and nervous control, immune systems, and
sensory and motor mechanisms (STEM_BIO11/12-IVa-h-1)

At the end of the lesson, the learners will be able to

1. state some basic principles in gas exchange;

2. describe the structures for gas exchange in plants and animals;
3. describe the organs in the human respiratory system and their roles;
4. discuss the coordination of gas exchange and circulation;
5. explain the functions of structures in animal circulation;
6. trace the path of blood in the systemic and the pulmonary circulation; and
7. describe the transport of substances in xylem and phloem;

Before going on, check how much you know about this topic. Answer the
pretest on the next page in a separate sheet of paper.

2
 Lesson Gas Exchange
1

Pretest: Read each question carefully then select the correct answer from the
given choices.

1. Which gas is released by plants during aerobic respiration?

A. Carbon dioxide B. Hydrogen C. Nitrogen D. Oxygen

2. Which structure in plants allow gas exchange?

A. Chloroplast B. Guard cells C. Stomata D. Epidermis

3. What organ in animals release carbon dioxide from the body?

A. Lung B. Intestine C. Kidney D. Throat

4. Which muscles contract to bring about respiration?

A. Cardiac B. Diaphragm C. Pulmonary D. Pelvic

5. When you breathe, what is taken in?

A. Air B. Carbon dioxide C. Oxygen D. Nitrogen

Jumpstart

One of the most essential events in everyday life of a living organism is the
exchange of gases. This process is important as it keeps organism alive. Carbon
dioxide, as a waste product during this process is removed from most animal systems
and substituted by oxygen. Plants on the other hand uses carbon dioxide in
photosynthesis to produce oxygen which will be used by animals and plants for
respiration. Gas exchange is responsible for the presence of oxygen and carbon
dioxide in the air.

For you to be more engaged in the lesson, do the following activity. Have
fun and good luck!

3
Activity 1: Breathing and Exercise
Background and Information:
Normal breathing rates from 12-25 times per minute. In this activity,
you will compare you breathing rate at rest to your breathing rate after
exercise.
Procedure:
1. Sit quietly and breathe for one minute. While you are doing this, count the
number of breaths (in and out is one count) you take.
2. Run in place for 30 seconds. Then sit down and again have your partner count
the number of breaths you take for 1 minute. Record this number in the data
table.
3. Run in place for 1 minute. Sit down and have your partner count the number
of breaths in 1 minute. Record this number in the data table.
Observations:
Activity Rate
Resting
After 30 seconds of exercise
After 1 minute of exercise

Analysis:
1. How did exercise affect your breathing rate?
___________________________________________________________________________
___________________________________________________________________________
2. What other factor besides exercise might influence your normal breathing
rate?
___________________________________________________________________________
_________________________________________________________________________
3. Did you notice any other way your breathing changed with exercise? Give a
possible reason for this change?
___________________________________________________________________________
___________________________________________________________________________

Discover

Carbon dioxide may appear to be a waste product of respiration in plant

cells, but carbon dioxide may be considered to be a by-product because it is
used in photosynthesis. Plant cells must have carbon dioxide available in
them while the oxygen gas must be eliminated. Gas exchange is an important
process in the metabolism of energy, and gas exchange is an essential
prerequisite for life.
Diffusion through a moist membrane is the fundamental process of
gas exchange. Diffusion is the movement of molecules in the direction
following the concentration gradient, from a region of greater concentration

4
to a region of lower concentration. The molecules travel through cell
membranes in living systems, which are constantly moistened by fluid.

Plants

While plants are complex organisms, they exchange their gases with
the atmosphere. Water moves through the tissues of aquatic plants and
provides the means for the exchange of carbon. Air enters the tissues of
terrestrial plants, and the gases diffuse through the moisture that bathes the
inner cells.
An abundant supply of carbon dioxide must be available in the leaves
of the plant, and oxygen from photosynthesis must be released. Gases do not
pass through the leaf cuticle; they pass through pores called stomata in the
epidermis. On the lower surface of the leaf, stomata are numerous and usually
open during the day when the rate of photosynthesis is highest. The opening
and closure of stomata are due to physiological changes in the surrounding
guard cells.

Figure 1. The Structure of a Stoma

Source:
https://commons.wikimedia.org/wiki/File:Opening_and_Closing_of_
Stoma.svg

Animals

Gas exchange follows the same general trend in animals as in plants.

Oxygen and carbon dioxide diffuses across moist membranes. The exchange
happens directly with the environment in simple animals. The exchange
between the environment and the blood happens with complex organisms,
such as mammals. The blood transports oxygen to deeply embedded cells and
transports carbon dioxide out of the body.
Oxygen and carbon dioxide are transferred by earthworms directly
through their skin. Oxygen diffuses into tiny blood vessels on the surface of
the skin where it mixes with hemoglobin, a red pigment. Hemoglobin loosely

5
binds to oxygen and brings it across the bloodstream of the animal.
Hemoglobin transports carbon dioxide back to the blood.
Terrestrial arthropods have a set of openings on the surface of the body
called spiracles. Spiracles open into tiny air tubes called tracheae, which grow
into fine branches that reach into all areas of the body of the arthropod.

Figure 2. The Tracheal System in Arthropods

Source:
https://commons.wikimedia.org/wiki/File:Opening_and_Closing_of_
Stoma.svg

Fishes use external

extensions of the surface of
their body, called gas
exchange gills. Gills are tissue
flaps which are richly
supplied by blood vessels.
This attracts water into its
mouth and through the
gills as a fish swims.
Oxygen spreads through the
gill's blood vessels from the
water, while carbon dioxide
exits the blood vessels and
enters the water flowing
through the gills.

Figure 3. The Tracheal System in Arthropods

Source: https://en.wikipedia.org/wiki/Fish_gill

There are well-developed respiratory systems with lungs for terrestrial

vertebrates such as amphibians, reptiles, birds, and mammals. In their
lungs, frogs swallow air, where oxygen diffuses the blood to bind with
hemoglobin in the red blood cells. By means of their skin, amphibians can
exchange gases as well. To provide increased surface space for gas exchange,

6
 reptiles have folded lungs. Rib muscles aid the expansion of the lungs and
protect the lungs from damage.
Birds have in their lungs large air spaces called air sacs. The rib cage
spreads apart when a bird inhales, and a partial vacuum is created in the
lungs. Air flows into the lungs and then into the air sacs, where much of the
exchange of gas takes place. This method is the adaptation of birds to the
rigors of flight and their enormous metabolic requirements.
Mammalian lungs are classified into millions of microscopic air sacs
called alveoli (the singular is alveolus). A rich network of blood vessels for
transporting gases surrounds each alveolus. Furthermore, mammals have a
dome-shaped diaphragm that separates the thorax from the abdomen,
providing a separate the chest cavity for breathing and blood circulating.
The diaphragm contracts and flattens to create a partial vacuum in the
lungs during inhalation. With air, the lungs fill, and gas exchange follows.

Figure 4. The Thoracic Cavity and Lungs

Source:https://open.oregonstate.education/aandp/chapter/22-2-the-lungs/

The Human Respiratory System

Gas exchange between the external atmosphere and the circulatory system of
an organism is the primary feature of the respiratory system. This exchange
combines the oxygenation of blood with the removal of carbon dioxide and other
metabolic waste from circulation in humans and other mammals.
Gas exchange occurs at the molecular level in the alveoli-tiny sacs that are
the essential functional part of the lungs. The alveolar epithelial tissue is extremely
thin and permeable, facilitating the exchange of gas between the air inside the lungs
and the blood stream capillaries. Air moves due to variations in pressure, where air
flows from high-pressure areas to low-pressure areas.
The key respiratory system organs work primarily to provide oxygen for
cellular respiration to body tissues, extract carbon dioxide from the waste product,
and help preserve acid-base balance. Sections of the respiratory system are also used

7
for non-vital purposes, such as odor detection, voice generation, and stress, such as
during childbirth or coughing.
In order to help you breathe, the respiratory system has several different parts
that function together. Your airways deliver your lungs with air. Your airways are a
complex structure, like your:

• Mouth and nose: Openings that pull air from outside your body into your
respiratory system.
• Sinuses: Hollow areas between the bones in your head that help regulate the
temperature and humidity of the air you inhale.
• Pharynx (throat): Tube that delivers air from your mouth and nose to the
trachea (windpipe).
• Trachea: Passage connecting your throat and lungs.
• Bronchial tubes: Tubes at the bottom of your windpipe that connect into each
lung.
• Lungs: Two organs that remove oxygen from the air and pass it into your
blood.

From your lungs, your bloodstream delivers oxygen to all your organs and
other tissues.

Muscles and bones help move the air you inhale into and out of your lungs.
Some of the bones and muscles in the respiratory system include your:

• Diaphragm: Muscle that helps your lungs pull in air and push it out
• Ribs: Bones that surround and protect your lungs and heart

When you breathe out, your blood carries carbon dioxide and other waste out
of the body. Other components that work with the lungs and blood vessels
include:

• Alveoli: Tiny air sacs in the

lungs where the exchange of
oxygen and carbon dioxide
takes place.
• Bronchioles: Small
branches of the bronchial
tubes that lead to the alveoli.
• Capillaries: Blood vessels in
the alveoli walls that move
oxygen and carbon dioxide.
• Lung lobes: Sections of the
lungs – three lobes in the
right lung and two in the left
lung.
• Pleura: Thin sacs that
surround each lung lobe and
separate your lungs from the
chest wall. Figure 4. The Respiratory System

Source: https://upload.wikimedia.org/
wikipedia/commons/e/e7/ Respiratory_

8
 System_%28Illustration%29.png

Some of the other components of your respiratory system include:

• Cilia: Tiny hairs that move in a wave-like motion to filter dust and other
irritants out of your airways.
• Epiglottis: Tissue flap at the entrance to the trachea that closes when you
swallow to keep food and liquids out of your airway.
• Larynx (voice box): Hollow organ that allows you to talk and make sounds
when air moves in and out.

Explore

Here are some enrichment activities for you to work on to master and
strengthen the basic concepts you have learned from this lesson.

Enrichment Activity 1
Activity 1: Sentence completion.
Directions: Answer the following questions. Use the word bank below to answer the
questions.

exhale muscles diaphragm air sacs

mouth cilia inhale brain
1. When we_____________ air enters the body through the nose and mouth.
2. Mucous and ____________ work to trap dirt and germs before we inhale.
3. The _______________ helps draw air into the lungs.
4. The structure where the respiratory system and the circulatory system meet
is the ________________.
5. The __________________ controls the rate of breathing.

Enrichment Activity 2
Activity 1: Construction of a crossword Puzzle.
Directions: Select 12 terms associated with gas exchange in both plants and
animals. With the identified terms, you are to prepare a crossword puzzle. Be sure
that you provide a description for each term. Use a separate sheet of paper for your
answer.
Rubric:
Crossword puzzle (12 points) 1 point per term included in the puzzle

Descriptions: (12) 1 point per correct description

Great job! You have understood the lesson. Are

you now ready to summarize?
9
 Deepen

At this point, you are now ready to apply the concepts of gas exchange in our
current pandemic situation. Aware that viruses can enter the body through the
respiratory passages, you are tasked to create catchy reminders to protect ourselves
from transmitting the Covid-19 virus. You may include images to highlight what you
want to convey. Post your output in your facebook wall. Make a screenshot and send
the picture to your teacher. (20 points)

Rubric
Category 4 3 2 1
Relevance (3) Output is Output is Output is poorly Output has no
thoroughly somewhat related to the connection to
related to the related to the topic the topic
topic topic
Content- Graphics and Graphics and Graphics and Graphics and
Originality (2) text reflect an text reflect a text reflect a text reflect no
exceptional certain degree of little degree of degree of
degree of creativity creativity creativity
creativity

10
 Lesson
Transport/Circulation
2

Pretest: Read each question carefully then select the correct answer from the
given choices.

1. What does the human circulatory system consist of?

A. blood and veins C. heart, blood vessels and blood
B. bones, muscles and hair D. lungs and heart

2. Oxygen is transported from _______________?

A. body cells to lungs C. kidneys to lungs
B. brain to lungs D. lungs to body cells

3. Which process transports minerals against the concentration gradient into

the root hair cell?
A. active transport B. diffusion C. facilitated diffusion D. osmosis

4. Which one of the following is NOT transported by blood around the body?
A. carbon dioxide B. hormones C. oxygen D. sweat

5. What is the main function of platelets?

A. fight diseases B. form clots C. carry oxygen D. boost immunity

Jumpstart

Multicellular organisms need to supply every cell with oxygen, water and
nutrients and to achieve this they need a transport mechanism otherwise diffusion
will be too long. The development of a transport system is thus directly related to an
organism’s surface area:volume ratio. Organisms which have a very large surface
area:volume ratio e.g. protozoans, may depend upon diffusion, but as an organism
grows bigger, the surface area to volume ratio reduces and this makes a specialised
transport mechanism necessary.

For you to be more engaged in the lesson, do the following activity. Have
fun and good luck!

11
Activity 1: Heart Zone
This activity will help you note changes in heart beat with different physical
activities.

Procedure:
*After each physical activity below, let your heart recover for 1-2 minutes
before starting the next activity.

*Count your heart beat for after doing the physical activity. Use watch
with second hand or any stopwatch.

Table 1. Physical Activities and Heart Rate

Physical activity Heart beat per minute
1. Sit in a chair-relaxed
2. Standing - relaxed
3.After walking at a leisurely pace for 3
minutes
4. After speed walking for 2 minutes
5. After 2 minutes of jogging in place
6. After 25 jumping jacks
7. After running in place as fast as possible for
1 minute

Questions:
1. What activity were you doing when your heart beat the fastest?
2. During the recovery time after an activity, what happened to your
heart rate?
3. Describe how you felt physically when your heart rate was increasing.

Discover

Transport in Plants

Plants need a transport system to supply raw materials for

photosynthesis to the leaves and to deliver the sugar made to other areas of
the plant for use or storage.

12
The Xylem Transport System
Water and minerals are carried up
through the stem in xylem vessels.
Xylem is a tissue composed of dead,
hollowed-out cells that form a web of
pipes. The walls of xylem cells are
lignified (strengthened with a
material called lignin) (strengthened
with a substance called lignin). This
allows the xylem to tolerate pressure
changes as water flows through the
plant. Transport in the xylem is a
physical process. It does not require
energy.
Figure 4. Xylem Transport System
Source:
https://www.bbc.co.uk/bitesize/
guides/z28g7p3/revision/1

The Phloem Transport System

Sugar formed by photosynthesis in the leaves is transferred up and
down the plant to the meristems and other tissues in living phloem cells. The
transported sugar is needed in the following processes: growing parts of the
plant for immediate use; storage organs such as bulbs and tubers;
developing seeds; and respiration.
Transport in the phloem is both up and down the stem. Transport of
substances in the phloem is termed translocation.
Phloem consists of living cells. The cells that make up the phloem are
adapted to their function:
▪ Sieve tubes - specialized for transport and contain no nuclei.
Each sieve tube has a perforated end so the cytoplasm binds
one cell to the next.

▪ Companion cells- supply the energy for the sieve cells. The end
walls of the sieve cells have pores from which sugar is
transferred from cell to cell.

13
 Figure 5. Phloem Transport System
Source:
https://commons.wikimedia.org/wiki/File:Phloem_cells.svg

The xylem and phloem are dispersed differently in roots and

stems. In the root, the xylem forms a central axis, forming a strong
support. The phloem is in the middle, above the xylem.
In the stem, the transport tissues of the xylem and phloem are
organized into vascular bundles.

Figure 6. The Vascular (Xylem and Phloem) Bundle

Source: https://upload.wikimedia.org/wikipedia/commons/1/12/Figu
re_30_ 02_06.jpg

14
 Transporting Water
Each organism is unable to prepare food on its own. For their nutrition,
such species rely on others. Heterotrophs are species which cannot produce
food on their own and rely on other sources/organisms.
Plants require transport mechanisms to carry water, dissolved food and
other substances around their structures in order to remain alive. Plants
require water for photosynthesis and for the transport of minerals.
Water enters root hair cells: tiny hairs covering the ends of the smallest
roots. They provide a large surface area for the absorption of water by the
process of osmosis. Water then moves from cell to cell through the root cortex
by osmosis down a concentration gradient. This means that each cell has a
lower water content than the one before it. In the center of the root the water
enters the xylem vessels - vein-like tissues that transport water and minerals
up a plant.
Water molecules move up the xylem vessels to the leaves where they
exit and move from cell to cell. Water moves from the xylem vessels into the
mesophyll cells where it can be used for photosynthesis.

Xylem to Leaf to Air

Some of the water evaporates into the surrounding air spaces inside
the leaf and then diffuses out through the stomata into the surrounding air.
The opening and closing of the stomata is controlled by guard cells in the
epidermis. The loss of water from the leaves of a plant is called transpiration,
and the resulting flow of water through the plant is called the transpiration
stream.

Transport System in Animals

Transport systems are crucial to survival. Unicellular organisms rely
on simple diffusion for transport of nutrients and removal of waste.
Multicellular organisms have developed more complex circulatory systems.

Parts of the Circulatory System

The average adult has 4.7 to 5.6 liters of blood composed of plasma
(fluid part of blood), red blood cells or erythrocytes (transports oxygen),
white blood cells (defense of the body) and platelets (blood clotting).
The heart is a four-chamber muscular organ. Located just behind and
just to the left of the breastbone, it pumps blood through a network of
arteries and veins called the cardiovascular system.
The network of arteries (carries oxygenated blood), and veins (carries
deoxygenated blood) or collectively called blood vessels brings oxygenated
blood from the heart, provides oxygen and nutrients to the cells of the
body, and then returns deoxygenated blood back to the heart.

Open Circulatory System

In an open circulatory system, the blood vessels carry all fluids to the
cavity. When the animal moves, the blood inside the cavity moves freely in
both directions throughout the body. Blood bathes the body immediately,
delivering oxygen and eliminating waste from the bloodstream.

15
 Blood moves at a very slow pace due to the lack of smooth muscles,
which, as you have learned earlier, are responsible for the contraction of
the blood vessels. The majority of invertebrates (crabs, flies, snails etc.)
have an open circulatory system.

Figure 7. Open Circulatory System

Source:https://upload.wikimedia.org/wikipedia/commons/4/45/Figure_40_
01_01ab.jpg

Closed Circulatory System

Closed circulatory systems are distinct from open circulatory systems

because blood never leaves the blood vessels. Instead, it is continually
moved from one blood vessel to another without entering the cavity.
Blood is transported in one direction, supplying oxygen and nutrients
to cells and removing waste materials.
The blood circulatory system (cardiovascular system) provides
nutrients and oxygen to all cells of the body. It consists of the heart and
the blood vessels that run through the whole body. The arteries carries
blood from the heart; the veins bring it back to the heart.
The system of blood vessels resembles a tree: the trunk – the primary
artery (aorta) – branches through large arteries, leading to smaller and
smaller vessels. The smallest arteries wind up in a network of tiny vessels
known as the capillary network.

The human circulatory system involves the pulmonary and systemic

circulatory systems. The pulmonary circulatory system consists of blood
vessels that transport deoxygenated blood from the heart to the lungs and
return oxygenated blood from the lungs to the heart.

Pulmonary circulation system

In the pulmonary circulation system, deoxygenated blood exits
the heart from the right ventricle and is transferred through the
pulmonary artery to the lungs. The pulmonary artery is the only artery
to carry deoxygenated blood. It carries blood to the capillaries where
carbon dioxide diffuses from the blood to the alveoli (lung cells) and
then to the lungs where it is exhaled. Simultaneously, oxygen diffuses

16
through the alveoli, and then to the blood and returns to the left atrium
of the heart through the pulmonary vein.

Systemic circulation
Systemic circulation refers to the portion of the circulation
system that exits the heart, takes oxygenated blood to the cells of the
body, and returns deoxygenated blood to the heart. Blood exits from the
left ventricle to the aorta, the body's largest artery. The aorta connects
to smaller arteries that supply all of the body's organs.
These arteries ultimately branch to the capillaries. In the
capillaries, oxygen diffuses from the blood to the cells, and the waste
and carbon dioxide diffuses from the cells and into the blood.
Deoxygenated blood in the capillaries then travels to the veins that
converge into the veins, where the blood is transferred back to the
heart. These veins converge into two main veins, namely the upper vena
cava and the lower vena cava (figure: double circulation). Deoxygenated
blood enters the right atrium from the upper vena cava. Major arteries
deliver blood to the brain, small intestine, liver, and kidneys. Systemic
circulation, however, also targets the other organs, including the
muscles and skin.

Figure 8. Pulmonary and Systemic Circulation

Source: https://commons.wikimedia.org/wiki/
File:2101_Blood_Flow_Through_the_Heart.jpg

17
Figure 8. Flow of Blood in the Body
Source: https://pixy.org/889066/

18
 Explore

Here are some enrichment activities for you to work on to master and
strengthen the basic concepts you have learned from this lesson.

Enrichment Activity 1.
Directions:
Illustrate and trace the flow of blood in a pulmonary circulation. Label your
illustration. Represent the flow of blood using colored arrows. Use red ink to
represent oxygenated blood and use blue ink for deoxygenated blood. Give a short
explanation of your illustration. (25 pts.)

Rubric
Excellent (5-4) Good (3-2) Needs Improvement
(1)
Drawing and Illustrated correctly Illustrated correctly Illustrated
labels (x2) with complete labels but with few errors incorrectly with
in the labels errors in the labels
Placement and Correct placement Few errors in the Incorrect placement
Direction of and direction of placement and and direction of
arrows arrows are observed direction of arrows arrows are observed
are observed
Color of arrows All arrows have Few arrows have Most arrows have
correct colors incorrect colors incorrect arrows
Explanation Correct Partly correct Incorrect

Enrichment Activity 2.
The figure shows the structure of an artery and a vein. Explain how the
structure of the artery is related to its function.

19
Enrichment Activity 3.
Compare and contrast transport in plants and animals. You can use any
form of presentation for this task.

Great job! You have understood the lesson. Are

you now ready to summarize?

Deepen

At this point, you are now ready to apply the concepts you learned on
transport or circulation. Design a simple experiment to illustrate transport in
plants.

Rubric
Excellent (5-4) Good (3-2) Needs Improvement
(1)
Content (x2) Title, materials, Title, materials, Some parts of the
procedure, and procedure, and experiment are
guide questions are guide questions are missing.
included. included.

Contents are well- Contents have few Contents have

written. errors. errors
Procedure Procedure is specific Procedure is partly Procedure is not
and very clear specific and specific and is
somewhat clear unclear
Feasibility The experiment can The experiment is The experiment is
be easily done. somewhat difficult difficult to do.
to do.

20
 Gauge

Directions: Read carefully each question and select the correct answer from the
given choices. Use separate sheet of paper for your answers. Write the letter only.

1. What structure in the leaf is the entry point of gases in plants?

A. Guard cells B. Mesophyll C. Palisade D. Stoma

2. Which of the following organisms exemplify gas exchange through the moist
skin?
A. Earthworm B. Fish C. Human D. Snake

3. Which structures in an arthropod allows the entry of gases into its body?
A. Gills B. Lung C. Skin D. Spiracles

4. What would happen if the lower epidermis of the leaves of plants become too
dusty?
A. Oxygen can readily exit from the plant.
B. Oxygen becomes abundant inside the plant.
C. Carbon dioxide is trapped in the leaves for respiration.
D. Carbon dioxide can hardly enter the plant resulting to reduced
photosynthesis.

5. When you hold your breath, which of the following gas changes in the blood
first leads to the urge to breathe?
A. Rising oxygen
B. Falling oxygen
C. Rising carbon dioxide
D. Rising carbon dioxide and falling oxygen

6. Where does gas exchange take place in the lungs?

A. Alveolus B. Alveolar bronchiole
C. Alveolar duct D. Bronchial tube

7. Which of the following filters the air in the respiratory passage?

A. Cilia B. Flagella C. Epithelial tissue D. Mucus

8. What structure in the respiratory system protects us from choking?

A. Epiglottis B. Larynx C. Pharynx D. Trachea

9. What are referred to as extensions of specialized epidermal cells that increase

the surface area for absorption in plants?
A. micorrhizae B. root hairs C. root nodules D.secondary roots

21
10. What happens in pulmonary circulation? In pulmonary circulation, there is
an exchange of gases between the _______
A. heart and the lungs. B. lungs and the kidneys.
C. heart and the kidneys. D. heart and the body parts.

11. What is transported by the xylem vessels in the vascular bundle?

A. food B. glucose C. starch D. water

12. Which of the following animals exhibit open circulatory system?

A. frog B. insect C. man D. snake

13. Which blood cell is responsible in bringing oxygen to the body cells?
A. erythrocyte B. blood platelet C. leucocyte D.lymphocyte

14. What is the process of removing water from plants?

A. absorption B. circulation C. respiration D. transpiration

15. Which blood vessel allows gas exchange with the cell?
A. artery B. capillaries C. vein D. none

22
 23
Lesson 1. Gas Exchange
Pre-Test
1. D
2. C
3. A
4. D
5. A
Enrichment Activity 1
1. inhale
2. cilia
3. mouth
4. air sacs
5. diaphragm
Lesson 2. Transport/Circulation
Pre-Test
1. C
2. D
3. A
4. D
5. A
Gauge
1. D
2. A
3. D
4. D
5. C
6. A
7. A
8. A
9. B
10. A
11. D
12. B
13. A
14. D
15. B
Answer Key
References
Printed Materials:

Dela Peña, Renato Jr., Gracilla, Daniel and Pangilinan, Christian. 2016. General
Biology. Pasay City: JFS Publishing Services

Website:
“The Respiratory System Packet”. Accessed at
https://www.tesd.net/cms/lib/PA01001259/Centricity/Domain/595/Respiratory
%20System%20Packet%2014.pdf

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