NAME:__________________________________________

GRADE/SECTION:______________________________
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GENERAL BIOLOGY 2
Semester II – Week 9
Gas Exchange
and Transport/Circulation
in Animals

CONTEXTUALIZED LEARNING ACTIVITY SHEETS

SCHOOLS DIVISION OF PUERTO PRINCESA CITY
General Biology 2 – Grade 12
Contextualized Learning Activity Sheets (CLAS)
Quarter IV - Week 2: Gas Exchange and Transport/Circulation in Animals
First Edition, 2020

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 Lesson 1
Gas Exchange and Transport/Circulation in
Animals

MELC: 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

Objectives:
1. Describe the different ways by which animals undergo respiration.
2. Differentiate open and close circulatory system.
3. Explain how the three-chambered heart and four-chambered heart function on the
vertebrate circulatory system.
4. Trace the flow of blood to and from the heart.

Let’s Try
Directions: Let us try to activate your prior knowledge about this topic by answering the
following questions. Choose and write only the letter of the best answer on the line provided
before the number.
_____1. Which body systems work together in taking in oxygen to all parts of the body?
A. Digestive and Circulatory C. Circulatory and Respiratory
B. Digestive and Muscular D. Circulatory and Muscular
_____2. Why do mammalian lungs contain an enormous number of minute alveoli?
A. More space for increasing the total volume of inspired air.
B. More surface area for diffusion of gases.
C. More spongy texture to keep lungs in proper shape.
D. More nerve supply to keep the organs working more efficiently.
_____3. Which of the following organisms has an open circulatory system?
A. Humans C. Dogs
B. Birds D. Grasshoppers
_____4. Which of the following respiratory surfaces do unicellular organisms such as
amoeba use in respiration?
A. plasma membrane C. gills
B. body surface D. trachea
_____5. Which of the following statements is correct?
A. External respiration is the process by which gas exchange takes place
with the environment while cellular respiration takes place in the
mitochondria of the cell.
B. External respiration takes in oxygen and gives off carbon dioxide while
cellular respiration takes in carbon dioxide and gives off oxygen.
C. External respiration takes place in the mitochondria of the cell while
cellular respiration takes place with the environment.
D. All of the above

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_____6. What is the correct breathing pattern for humans?
A. nose -> mouth -> larynx-> pharynx -> bronchioles->trachea-> alveoli
B. nose -> mouth ->larynx ->trachea-> pharynx ->bronchioles-> alveoli
C. nose ->mouth->pharynx->larynx->trachea->bronchioles -> alveoli
D. nose-> mouth->trachea->pharynx->larynx ->bronchioles ->alveoli
_____7. In amphibians and most reptiles, there is a mixing of oxygenated and deoxygenated
blood. Which best describes the heart of these animals?
A. Two-chambered heart C. Four-chambered heart
B. Three-chambered heart D. Both B and C
_____8. What is the correct sequence of blood flow in the following chambers of the heart?
A. right atrium->right ventricle->left atrium->right ventricle
B. right atrium->right ventricle->left atrium->left ventricle
C. right atrium->left ventricle->left atrium->right ventricle
D. right atrium->left ventricle->left atrium->left ventricle
_____9. Which of the following is not a function of the circulatory system?
A. Delivers oxygen and nutrients to the cell.
B. Breakdowns carbohydrates into glucose.
C. Removes CO2 and wastes from the cells.
D. Transports other materials through the body.
_____10. What is the major difference between open and closed circulatory systems?
A. Function C. Color of the blood
B. Material transported D. Structure and design of vessels

Let’s Explore and Discover

Gas Exchange
Unlocking Word Difficulties
Oxygen is essential to all animals, most
especially for the production of energy in the
Respiration- uptake of O2 and release of form of adenosine triphosphate or ATP. How
CO2 can animals acquire oxygen then? It is a
Open Circulatory system- blood is not process of respiration or simply gas
enclosed in a blood vessel exchange- the uptake of O2 from the
environment and the release of CO2. There are
Valves- prevent the backward flow of the
two types of respiration; one is external
blood.
respiration and the other, cellular respiration.
External respiration is the process by which gas exchange takes place with the
environment to supply cellular respiration. In a multicellular organism, it happens using
special structures or organs. On the other hand, cellular respiration is the transformation
of chemical energy, glucose plus oxygen into ATP, yielding CO 2 as a waste product. This
happens in the mitochondria of a cell.
Respiration of Different Animals
Unicellular organisms such as amoeba and other protozoans use their plasma
membrane as a respiratory surface with simple diffusion as their mode of gas exchange.
Higher forms of animals require a moist respiratory surface to dissolve gases first before
they transport these gases into cells. Some invertebrates such as insects use a highly
branched chitin-lined tube called the trachea to exchange gas with the environment while
some other invertebrates are maximizing the function of their integument or body surface
to act as a surface for respiration. Most aquatic animals, such as fishes have adapted ways
to obtain oxygen from water using their gills- out-folding of the body surface suspended in
water. The early stage of amphibians also has gills to enable them to respire in the aquatic
environment.
2

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 Figure 1- The gills are respiratory surfaces of fishes (left) and trachea for insects.
Source: Animal Respiration,https://goprep.co/describe-the-process-of-respiration-in-fish-i-
1nje13

Mammals and other vertebrates have lungs, a highly vascularized organ of the body
restricted to a specific location. The adult stage of most amphibians uses lungs while they
can also respire through their skin. In some reptiles such as turtles, they use the moist of
their mouth and anus for respiration to supplement their lungs.
The Mammalian Respiratory System
Gas exchange in mammals occurs in three general phases, first by an alternating
inhalation-exhalation process called breathing. Then, the circulatory system carries the
oxygen from the
lungs to the rest of
the body followed by
the removal of
oxygen from the
blood and
subsequent
discharge of CO2
from the body’s cells.
The sequential
manner of
respiration starts
from the nose and
mouth to the
pharynx leading to
the larynx and
trachea. O2 enters
the lungs via the
bronchi going to the
smallest branches of
tubes called
bronchioles and
eventually to the
alveoli (air sacs) in
which gas exchange
between alveoli and
capillary occurs.
Figure 2 shows the
various organs that
comprise the human
respiratory system.

Figure 2- The Human Respiratory System

Source:https://en.wikipedia.org/wiki/Respiratory_system#/media/Fi
le:Respiratory_system_complet

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Circulation and Transport
The circulatory system provides a mechanism for the transport of gases, nutrients,
and waste products going in and out of the cell. Among unicellular organisms, they
accomplish this directly across the plasma membrane, while multicellular organisms
adapted a sophisticated method for transport. Most invertebrates do not have a true
circulatory system making their transport process simple yet advantageous. The presence
of a gastrovascular cavity does not only provide digestive purpose but also aids transport.
Sponges and most cnidarians, for instance, use water from their environment as a
circulatory fluid. In this case, transport occurs via diffusion directly through their tissues
toward the gastrovascular cavity.
Types of Circulatory System
1. Open Circulatory System- blood and interstitial fluid do not have any distinction.
The hemolymph serves both blood and interstitial fluid. In most mollusks and
arthropods, the heart pumps the hemolymph through a network of channels and
body cavities. This eventually drains back to the central cavity where it will bathe
the internal organs.
2. Closed Circulatory System- all vertebrates and some invertebrates including,
cephalopod, mollusks, and annelids have closed circulatory systems consisting of
heart, blood vessels, and blood-their circulatory fluid which circulates all through
the body via blood vessels away and back to the heart. This circulatory system
provides a distinction between the blood and interstitial fluid.

Figure 3. Open circulation in grasshopper (left) closed circulation in a worm (right)

Source: Open vs. closed Circulatory System,https://study.com/academy/lesson/closed-
circulatory-system-definition-advantage-quiz.html

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Vertebrate Circulatory System

Figure 4- Hearts of Different Animals

Source:Comparative Anatomy of Vertebrate Hearts,
https://www2.nau.edu/lrm22/lessons/heart_evolution/heart_evolution.html

From an evolutionary perspective, vertebrates have adapted complex structures

suitable for their size along with the increase in physiological complexity. Take fishes as
an example. Their simplicity allows them to evolve having a two-chambered heart to
improve the efficacy of gas exchange in their gills. In amphibians and most reptiles, there
is a mixing of oxygenated and deoxygenated blood having a three-chambered heart
consisting of two atria and one
ventricle. The atrium receives
blood returning to the heart
and the ventricle pumps
blood out of the heart. Some
reptilian species and some
amphibians already evolved to
have a four-chambered heart
that reduces the mixing of the
blood in the heart. The
mammalian and avian(birds)
circulatory system is so far the
most sophisticated having a
four-chambered heart, two
atria, and two ventricles that
completely separate
oxygenated from
deoxygenated blood. This
allows the development of a
double circulation system
that provides pressure to
transport blood throughout
the body. This circulation
divides into pulmonary
circulation that transports
blood from the heart and
lungs, and systemic
circulation to bring blood to
Figure 4- Double circulation system is showing pulmonary
the heart and the rest of the
and systemic circuits.
Source: Double Circulatory Circuits body.
http//labspace.open.ac.uk

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 The Human Heart
Look at your
fist. Note its size.
Your heart is a
bundle of muscle
cells about the size
of your fist. The
heart is shaped like
a cone. It is located
in the center of your
chest between the
lungs. It is tilted to
the right and points
downward to the
left. Your heart is a
living pump. It is
two pumps in one, a
pump on the left
side and a pump on
the right side. Each
side is divided
across into two
chambers. The top
chamber is the
atrium and the
Figure 5- The Diagram of how the blood flow through the heart. bottom chamber is
Source: Structure of the Heart called the ventricle.
https://www.researchgate.net/figure/Structure-of-the-heart-Blood- Both sides of the
flow-through-the-chambers-and-heart-valves- heart are divided in
Figure_fig1_327558169 the same way. There
is a valve between
each atrium and ventricle to prevent the blood from flowing backward. The valves are like
one-way doors that keep the blood flow in one direction.
The Flow of Blood Through the Heart
Blood enters the heart through two large veins – the posterior (inferior) and the anterior
(superior) vena cava – carrying deoxygenated blood from the body into the right atrium.
Blood flows from the right atrium into the right ventricle through the tricuspid valve.
When the ventricle is full, the tricuspid valve shuts to prevent blood from flowing backward
into the atrium. Blood leaves the heart through the pulmonary valve into the pulmonary
artery and flows to the lungs. The pulmonary vein carries oxygen-rich blood from the
lungs into the left atrium. Blood flows from the left atrium into the left ventricle through
the open mitral valve. When the ventricle is full, the mitral valve shuts to prevent blood
from flowing backward into the atrium. Blood leaves the heart through the aortic valve
into the aorta and to the rest of the body.

(Source: Renato A. Dela Pena et.al, General Biology Combined Book 1 & 2, JFS
Publishing Services,2016, pp.113-117.)

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 Let’s Practice
ACTIVITY 1
D

Directions: By row, align the words from Columns B and C that are related to the terms
in Column A. Fill in the boxes with your answers.

B C
body surface for respiration fishes
simple diffusion some invertebrates
highly-branched chitin tube mammals
out-folding of the body surface protozoans
highly vascularized organ insects

A B C
1. trachea
2. plasma
membrane
3. lungs
4. integument
5. gills

ACTIVITY 2

Directions: Write the function of the following parts of the heart.

1. Right atrium- _________________________________________________________________.

2. Right ventricle- ________________________________________________________________.
3. Tricuspid valve- _______________________________________________________________.
4. Aortic valve- ___________________________________________________________________.
5. Left atrium- ___________________________________________________________________.
6. Left ventricle- _________________________________________________________________.

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 Let’s Do More

ACTIVITY 1
Directions: Trace how the blood passes through the heart. Write the letter that corresponds
to each number from 1-13.

A. Blood returning from the body

travels through a blood vessel
connected to the heart.
B. The blood enters the right atrium.
C. After the right atrium fills, the atria
contract. This pushes the blood past
a one-way valve.
D. The blood fills the right ventricle.
E. The ventricles contract and push the
blood which passes another valve
into a blood vessel.
F. This blood vessel goes to the lungs
where the blood picks up oxygen.
G. Blood from the lung travels through
a blood vessel to the heart.
H. The blood enters the right atrium.
I. After the left atrium is filled, it
contracts.
J. The blood fills the left ventricle.
K. The ventricles contract and push the blood to a valve into a blood vessel.
L. This blood, rich in oxygen, goes to the body.

ACTIVITY 2
Directions: Answer the following questions.
1. Differentiate closed and open circulatory systems.
__________________________________________________________________________________
__________________________________________________________________________________
_________________________________________________________________________________.

2. Draw a three-chambered heart and explain how it works for amphibians and most
reptiles.

__________________________________________
__________________________________________
_________________________________________.

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 Let’s Sum It Up
Directions

Directions: Answer the following question. Write your answer in the space provided.

1. Briefly explain the interrelatedness of the functions of the respiratory system

and circulatory systems.
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________.

Let’s Assess
Directions: Let us see how well you learned the lesson by answering the following
questions. Choose and write only the letter of the best answer on the line provided before
the number.
_____1. What is the major difference between open and closed circulatory systems?
A. Function C. Color of the blood
B. Material transported D. Structure and design of vessels
_____2. Which of the following is NOT a function of the circulatory system?
A. Delivers oxygen and nutrients to the cell.
B. Breakdowns carbohydrates into glucose.
C. Removes CO2 and wastes from the cells.
D. Transports other materials through the body.
_____3. What is the correct sequence of blood flow in the following chambers of the heart?
A. right atrium->right ventricle->left atrium->right ventricle
B. right atrium->right ventricle->left atrium->left ventricle
C. right atrium->left ventricle->left atrium->right ventricle
D. right atrium->left ventricle->left atrium->left ventricle
_____4. In amphibians and most reptiles, there is a mixing of oxygenated and deoxygenated
blood. Which best describes the heart of these animals?
A. Two-chambered heart C. Four-chambered heart
B. Three-chambered heart D. Both B and C
_____5. What is the correct breathing pattern for humans?
A. nose -> mouth -> larynx-> pharynx -> bronchioles->trachea-> alveoli
B. nose -> mouth ->larynx ->trachea-> pharynx ->bronchioles-> alveoli
C. nose ->mouth->pharynx->larynx->trachea->bronchioles -> alveoli
D. nose-> mouth->trachea->pharynx->larynx ->bronchioles ->alveoli

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_____6.Which body systems work together in taking in oxygen to all parts of the body?
A. Digestive and circulatory C. Circulatory and respiratory
B. Digestive and muscular D. Circulatory and muscular
_____7. Why do mammalian lungs contain an enormous number of minute alveoli?
A. More space for increasing the total volume of inspired air.
B. More surface area for diffusion of gases.
C. More spongy texture to keep lungs in proper shape.
D. More nerve supply to keep the organs working more efficiently
_____8. Which of the following organisms has an open circulatory system?
A. Humans C. Dogs
B. Birds D. Grasshopper
_____9. Which of the following respiratory surfaces do unicellular organisms such as
amoeba use in respiration?
A. plasma membrane C. gills
B. body surface D. trachea
_____10. Which of the following statements is correct?
A. External respiration is the process by which gas exchange takes place with
the environment while cellular respiration takes place in the mitochondria
of the cell.
B. External respiration takes in oxygen and gives off carbon dioxide while
cellular respiration takes in carbon dioxide and gives off oxygen.
C. External respiration takes place in the mitochondria of the cell while
cellular respiration takes place with the environment.
D.All of the above

I hope you enjoyed and learned something new!

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4
 Answer Key
Let’s Practice: Activity 1 Let’s Practice: Activity 2-Possible answers
trachea Highly branched Insects
chitin tube Right atrium- receive blood from superior
plasma Simple diffusion protozoans and inferior vena cava
membrane Right ventricle-receive blood from RA to
Lungs Highly Mammals pulmonary artery
vascularized organ Tricuspid valve-prevents backflow of blood
integument Body surface for Some from RV to RA
respiration invertebrates Aortic Valve-prevents backflow of blood
Gills Outfolding of the fishes from aorta to left ventricle
body Left atrium-receives oxygenated blood
from pulmonary vein
Left Venticle-receives blood from left
atrium

Let’s Do More: Activity 1

1.A 2. F 3. G 4.I 5. K 6.J 7.D
Let’s Sum it Up-Possible Answers
8. H 9. B. 10.L 11. E 12. C 13. A
The circulatory and respiratory
systems work together to circulate
Let’s Do More: Activity 2-Possible answers blood and oxygen throughout the
1.In closed circulatory system,blood can flow through body. Air moves in and out of the lungs
vessels inside the body such as arteries and veins while through the trachea, bronchi, and
Open circulation happens when there are no vessels to bronchioles. Blood moves in and out of
contain the blood and it flows freely through the cavities of the lungs through the pulmonary
the body. arteries and veins that connect to the
2. Answers may vary heart.

Let’s Try Let’s Assess

1. C 2. B 3. D 4. A 5. A 1. D 2. B 3. B 4. B 5. C
6. C 7. B 8. B 9. B 10. D 6. C 7. B 8. D 9.A 10.A

References
Book

Dela Pena, Renato A., Daniel E. Gracilla, and Christian R. Pangilinan. General Biology
Combined Book 1 & 2. JFS Publishing Services. 2016.

Basco-Tiamzon, Maria Elena Z., Avissar Yael., Choi Jung., Desaix Jean, Jurukovski
Vladimir, Wise Robert, Rye Connie, General Biology 2, Vibal Group Inc. 2016.

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