Lesson Transport and Circulation

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What I need to know
Learning Competency
The learners compare and contrast transport and circulation in plants and
animals (STEM_BIO11/12-IVa-h-1)

Specific Learning Outcomes

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

• explain the functions of structures in animal circulation; and
• trace the path of blood in the systemic and the pulmonary circulation
• describe the transport of substances in xylem and phloem;

What I know

PRIOR KNOWLEDGE: Define the following words.

1. Xylem
2. Phloem
3. Diffusion
4. Cell transport
5. Circulation
6. Arteries
7. Veins
8. Valves
9. Systemic Circulation
10. Pulmonary Circulation

What’s new

PRE ACTIVITY:

1. What are the functions of xylem and phloem?

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 What’s is it

INTRODUCTION:

Plants have two systems for the transportation of substances, by using two different types of transport
tissue. Water and solutes are transported by the xylem from the roots to the leaves, while food is
transported by the phloem from the leaves to the rest of the plant. Transpiration is the process by
which water evaporates from the leaves, therefore causing more water to be drawn up from the roots.
Plants have adaptations in order to reduce the excessive loss of water.

Xylem and phloem

There are two transport systems present in the plant to move food, water and minerals through their
roots, stems and leaves. These systems make use continuous tubes called the xylem and phloem which
are also known as vascular bundles.

Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of
the leaf. This is called transpiration.

https://sites.google.com/site/biopt14operationplant/plant-transportsystem#:~:text=
There%20are%20two%20transport%20systems,also%20known%20as%20vascular%20bundles.
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.

There are two types of circulatory systems found in animals: open and closed circulatory systems.
Open circulatory systems
In an open circulatory system, blood vessels transport all fluids into a cavity. When the animal
moves, the blood inside the cavity moves freely around the body in all directions. The blood bathes

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the organs directly, thus supplying oxygen and removing waste from the organs. Blood flows at a
very slow speed due to the absence of smooth muscles, which, as you learnt previously, are
responsible for contraction of blood vessels. Most invertebrates (crabs, insects, snails etc.) have an
open circulatory system

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. In the systemic
circulatory system, blood vessels transport oxygenated blood from the heart to various organs in the
body and return deoxygenated blood to the heart.

Pulmonary circulation system

In the pulmonary circulation system, deoxygenated blood leaves the heart through the right ventricle
and is transported to the lungs via the pulmonary artery. The pulmonary artery is the only artery that
carries deoxygenated blood. It carries blood to the capillaries where carbon dioxide diffuses out of
the blood into the alveoli (lung cells) and then into the lungs, where it is exhaled. At the same time,
oxygen diffuses into the alveoli, and then enters the blood and is returned to the left atrium of the
heart via the pulmonary vein.

Systemic circulation
Systemic circulation refers to the part of the circulation system that leaves the heart, carrying
oxygenated blood to the body's cells, and returning deoxygenated blood to the heart. Blood leaves
through the left ventricle into the aorta, the body's largest artery. The aorta leads to smaller arteries
that supply all organs of the body. These arteries finally branch into capillaries. In the capillaries,
oxygen diffuses from the blood into the cells, and waste and carbon dioxide diffuse out of cells and
into blood. Deoxygenated blood in capillaries then moves into venules that merge into veins, and the
blood is transported back to the heart. These veins merge into two major veins, namely the superior
vena cava and the inferior vena cava (figure:doublecirculation). The movement of blood is indicated
by arrows on the diagram. The deoxygenated blood enters the right atrium via the the superior vena
cava. Major arteries supply blood to the brain, small intestine, liver and kidneys. However, systemic
circulation also reaches the other organs, including the muscles and skin

Pulmonary circulation system

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The systemic circulatory system supplies blood to the entire body.

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 Lesson Regulation of Body Fluids
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What I need to know

Learning Competency
The learners shall be able to describe excretory systems in animals especially the
human urinary system and their functions in homeostasis.
(STEM_BIO11/12-IVa-h-1)

Specific Learning Outcomes

At the end of the lesson, the learners will be able to:
• define some key terms related to osmoregulation;
• describe different types of animals based on the osmolarity of their body fluids in relation to the
environment;
• enumerate the three types of nitrogenous wastes in animals;
• enumerate and describe excretory systems in invertebrates;
• characterize the mammalian urinary system and the role of nephrons; and
• analyze the role of the kidneys in the body’s acid-base balance.

What I know

PRIOR KNOWLEDGE: Definition of Terms

1. Internal Environment 6. Osmoregulators
2. Osmolarity 7. Ammonia
3. Osmosis 8. Urea
4. Osmoregulation 9. Uric acid
5. Osmoconformers 10. Filtration

What’s new

PRE ACTIVITY: Answer the following questions briefly.

1. What are the possible consequences should there be a failure in the ability of the body to dispose
or eliminate toxic metabolic wastes?
2. What are the two types of animals based on the osmolarity of their body fluids in relation to the
environment?
3. Identify the three types of nitrogenous wastes excreted by animals.

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 What’s is it

INTRODUCTION:

Osmosis is the movement of solvent molecules through a semipermeable membrane into an area that
has a higher solute concentration. Osmotic pressure is the external pressure needed to prevent the
solvent from crossing the membrane. Osmotic pressure depends on the concentration of solute
particles. In an organism, the solvent is water and the solute particles are mainly dissolved salts and
other ions, since larger molecules (proteins and polysaccharides) and nonpolar or hydrophobic
molecules (dissolved gases, lipids) don't cross a semipermeable membrane. To maintain the water and
electrolyte balance, organisms excrete excess water, solute molecules, and wastes.

Osmoregulation Strategies of Different Organisms

Bacteria - When osmolarity increases around bacteria, they may use transport mechanisms to absorb
electrolytes or small organic molecules. The osmotic stress activates genes in certain bacteria that lead
to the synthesis of osmoprotectant molecules.

Protozoa - Protists use contractile vacuoles to transport ammonia and other excretory wastes from
the cytoplasm to the cell membrane, where the vacuole opens to the environment. Osmotic pressure
forces water into the cytoplasm, while diffusion and active transport control the flow of water and
electrolytes.

Plants - Higher plants use the stomata on the underside of leaves to control water loss. Plant cells rely
on vacuoles to regulate cytoplasm osmolarity. Plants that live in hydrated soil (mesophytes) easily
compensate for water lost from transpiration by absorbing more water. The leaves and stem of the
plants may be protected from excessive water loss by a waxy outer coating called the cuticle. Plants
that live in dry habitats (xerophytes) store water in vacuoles, have thick cuticles, and may have
structural modifications (i.e., needle-shaped leaves, protected stomata) to protect against water loss.
Plants that live in salty environments (halophytes) have to regulate not only water intake/loss but also
the effect on osmotic pressure by salt. Some species store salts in their roots so the low water potential
will draw the solvent in via osmosis. Salt may be excreted onto leaves to trap water molecules for
absorption by leaf cells. Plants that live in water or damp environments (hydrophytes) can absorb
water across their entire surface.

Animals - Animals utilize an excretory system to control the amount of water that is lost to the
environment and maintain osmotic pressure. Protein metabolism also generates waste molecules
which could disrupt osmotic pressure. The organs that are responsible for osmoregulation depend on
the species.

Osmoregulation in Humans

In humans, the primary organ that regulates water is the kidney. Water, glucose, and amino acids may
be reabsorbed from the glomerular filtrate in the kidneys or it may continue through the ureters to
the bladder for excretion in urine. In this way, the kidneys maintain the electrolyte balance of the
blood and also regulate blood pressure. Absorption is controlled by the hormones aldosterone,
antidiuretic hormone (ADH), and angiotensin II. Humans also lose water and electrolytes via
perspiration.

Osmoreceptors in the hypothalamus of the brain monitor changes in water potential, controlling thirst
and secreting ADH. ADH is stored in the pituitary gland. When it is released, it targets the endothelial
cells in the nephrons of the kidneys. These cells are unique because they have aquaporins. Water can

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pass through aquaporins directly rather than having to navigate through the lipid bilayer of the cell
membrane. ADH opens the water channels of the aquaporins, allowing water to flow. The kidneys
continue to absorb water, returning it to the bloodstream, until the pituitary gland stops releasing
ADH.

https://www.thoughtco.com/osmoregulation-definition-and-explanation-
4125135#:~:text=Plants%20%2D%20Higher%20plants%20use%20the,vacuoles%20to%20regulate%2
0cytoplasm%20osmolarity.&text=Animals%20%2D%20Animals%20utilize%20an%20excretory,enviro
nment%20and%20maintain%20osmotic%20pressure.

What’s more

ACTIVITY:

1. Identify the structures and functions of the Kidney.

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 Lesson
Immune Systems
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What I need to know

Learning Competency
The learners shall be able to explain how immune systems work
(STEM_BIO11/12-IVa-h-1)

Specific Learning Outcomes

At the end of the lesson, the learners will be able to:
• compare innate and adaptive immune responses;
• define the term “antibody”;
• name the different kinds of antibodies produced by humans; and
• explain the function of each type of antibody.
• explain where T cells come from;
• identify the different types of T cells and
• describe the functions of T cells

What I know

PRIOR KNOWLEDGE: Definition of Terms

1. Innate immune Response

2. Adaptive immune response
3. Immunity
4. Humoral Response
5. Cell mediated response
6. antibodies
7. antigen
8. infection

What’s new

PRE-ACTIVITY:

1. What are the different types of Immunity?

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 What’s is it
The immune system is typically divided into two categories--innate and adaptive--although these
distinctions are not mutually exclusive.

Innate immunity
Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within
hours of an antigen's appearance in the body. These mechanisms include physical barriers such as
skin, chemicals in the blood, and immune system cells that attack foreign cells in the body. The innate
immune response is activated by chemical properties of the antigen.
Adaptive immunity
Adaptive immunity refers to antigen-specific immune response. The adaptive immune response is
more complex than the innate. The antigen first must be processed and recognized. Once an antigen
has been recognized, the adaptive immune system creates an army of immune cells specifically
designed to attack that antigen. Adaptive immunity also includes a "memory" that makes future
responses against a specific antigen more efficient.

http://www.biology.arizona.edu/immunology/tutorials/immunology/page3.html

Human antibodies are classified into five isotypes (IgM, IgD, IgG, IgA, and IgE) according to their H
chains, which provide each isotype with distinct characteristics and roles.

IgG
IgG is the most abundant antibody isotype in the blood (plasma), accounting for 70-75% of human
immunoglobulins (antibodies). IgG detoxifies harmful substances and is important in the recognition
of antigen-antibody complexes by leukocytes and macrophages. IgG is transferred to the fetus through
the placenta and protects the infant until its own immune system is functional.

IgM
IgM usually circulates in the blood, accounting for about 10% of human immunoglobulins. IgM has a
pentameric structure in which five basic Y-shaped molecules are linked together. B cells produce IgM
first in response to microbial infection/antigen invasion.

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Although IgM has a lower affinity for antigens than IgG, it has higher avidity for antigens because of
its pentameric/hexameric structure. IgM, by binding to the cell surface receptor, also activates cell
signaling pathways. IgA
IgA is abundant in serum, nasal mucus, saliva, breast milk, and intestinal fluid, accounting for 10-15%
of human immunoglobulins. IgA forms dimers (i.e., two IgA monomers joined together). IgA in breast
milk protects the gastrointestinal tract of neonates from pathogens.
IgE
IgE is present in minute amounts, accounting for no more than 0.001% of human immunoglobulins. Its
original role is to protect against parasites. In regions where parasitic infection is rare, IgE is primarily
involved in allergy. IgD
IgD accounts for less than 1% of human immunoglobulins. IgD may be involved in the induction of
antibody production in B cells, but its exact function remains unknown.

https://ruo.mbl.co.jp/bio/e/support/method/antibodyisotype.html#:~:text=Human%20antibodies%2
0are%20classified%20into,with%20distinct%20charact
eristics%20and%20roles.&text=IgG%20is%20the%20most%20abundant,of%20human%20immunogl
obulins%20(antibodies).

T cell: A type of white blood cell that is of key importance to the immune system and is at the core of
adaptive immunity, the system that tailors the body's immune response to specific pathogens. The T
cells are like soldiers who search out and destroy the targeted invaders.

Immature T cells (termed T-stem cells) migrate to the thymus gland in the neck, where they mature
and differentiate into various types of mature T cells and become active in the immune system in
response to a hormone called thymosin and other factors. T-cells that are potentially activated against
the body's own tissues are normally killed or changed ("down-regulated") during this maturational
process.
https://www.medicinenet.com/script/main/art.asp?articlekey=11300

There are 3 main types of T cells: cytotoxic, helper, and regulatory. Each of them has a different role
in the immune response.

Cytotoxic T cells (CD8+)

Cytotoxic T cells (Tc cells) have a co-receptor called CD8 on their cell surface. CD8 partners with the T
cell receptor and with MHC class I molecules, acting as a sort of bridge. This bridge allows cytotoxic T
cells to recognize normal cells that are infected by a pathogen. When the cytotoxic T cell recognizes
the infected cell, it becomes activated and produces molecules that kill the infected cell, destroying
the pathogen in the process.

Helper T cells (CD4+)

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Helper T cells (Th cells) have a different co-receptor called CD4 on their cell surface. CD4 also partners
with the T cell receptor but interacts with MHC class II molecules instead of MHC class I molecules.
This allows helper T cells to recognize pathogen peptides that have been displayed by antigen
presenting cells. When helper T cells recognize a peptide on an antigen presenting cell, they become
activated and begin to produce molecules called cytokines that signal to other immune cells.

Regulatory T cells (Treg cells) also have CD4 on their surface, but they do not activate the immune
system like helper T cells do. Instead, regulatory T cells play a protective role by shutting off the
immune response when it is no longer needed. This prevents excessive damage to the normal cells
and tissues in the body. Regulatory T cells suppress the immune response in several ways, including:

• Producing anti-inflammatory cytokines that suppress the immune response

• Releasing molecules that kill activated immune cells
• Changing the way dendritic cells behave so they can't activate T cells

https://www.celiackidsconnection.org/2018/05/06/what-are-the-different-types-of-
tcells/#:~:text=There%20are%203%20main%20types,role%20in%20the%20immune%20response.&t
e xt=Cytotoxic%20T%20cells%20(Tc%20cells,as%20a%20sort%20of%20bridge.

What’s more

ACTIVITY:

Answer the following questions on a separate sheet of paper:

a. Describe when inflammation is good and when it is bad.
b. What are the five hallmarks of inflammation?
c. What is the importance of inflammation in the immune response?

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References

Manuals/Modules/Lesson Exemplar

The Commission on Higher Education. Teaching Guide for Senior High School
General Biology 2

Department of Education Central Office. Most Essential Learning Competencies

( MELCs). 2020.

Websites

1.https://www.macmillanhighered.com/BrainHoney/Resource/6716/digital_first_content/trunk/tes
t/hillis2e/hillis2e_ch14_2.html
https://www.evolvingsciences.com/Photosynthesis%20worksheet%20.html

https://www.s-cool.co.uk/a-level/biology/gas-exchange/revise-it/gas-exchange-
inplants#:~:text=Plants%20obtain%20the%20gases%20they,underside%20of%20the%20leaf%20%2D
% 20stomata.

https://www.s-cool.co.uk/a-level/biology/gas-exchange/revise-it/gas-exchange-
inplants#:~:text=Plants%20obtain%20the%20gases%20they,underside%20of%20the
%20leaf%20%2D%

http://jyssbio5158.weebly.com/the-human-eye.html

https://open.oregonstate.education/aandp/chapter/13-1-sensory-receptors/

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