CBSE-i
Class VII – Biology
Unit: 15
Respiration in Organisms
CONTENTS
1. Preface
2. Acknowledgement
3. Syllabus
4. Scope Document
i.
ii.
Learning objectives
Extension Activities
iii.
Cross curricular links
5. Teacher Notes (TN)
i.
Matrix
ii. Teacher Guidelines for activities
iii. Rubric: Assessment of learning
6. Teacher Student Support Material (TSSM)
i.
Introduction
ii.
Importance of Respiration
iii.
Breathing and Respiration
a. Breathing
 Activity 1
 Activity 2
b. Breathing rate
 Activity 3
 Activity 4
c. Is breathing and Respiration the same?
iv.
Aerobic and Anaerobic Respiration
a. Aerobic
 Activity 5
b. Anaerobic
 Activity 6
v.
Respiratory System of Humans
a. Nose
 Activity 7
 Worksheet 1
b. Wind pipe/Trachea
c. Lungs
d. Bronchi/Bronchioles
vi.
Mechanism of Breathing
 Activity 8
 Activity 9
 Worksheet 2
a. Journey of Oxygen and Carbon dioxide in body cells
 Worksheet 3
b. How is Energy consumed?
vii.
Breathing in Other Animals
a. Earthworm
b. Cockroach
c. Frog
d. Fish
 Worksheet 3
viii.
Respiration and Exchange of gases in Plants
7. Post Content Worksheet 1
8. Post Content Worksheet 2
9. Glossary
10.E – Resources
Syllabus
 Importance of Respiration
 Breathing and Respiration
 Aerobic and Anaerobic respiration
 Respiratory system of humans
 Process of breathing in earthworm, cockroach and fish
 Respiration and exchange of gases in plants
Scope Document
Learning Objectives
At the end of the unit the learners will be able to:

Understand that breathing is inhalation of air and exhalation of CO2.

Correlate the role of O2 in the breakdown of food in order to release energy.

Compare breathing with respiration.

Analyze that breathing is a physical process, which involves movement of lungs
and respiration is a biochemical process which takes place though out the cell.

Differentiate between aerobic and anaerobic respiration

Define cellular respiration and state the steps of cellular respiration.

Describe the structure of various organs of human respiratory system and
appreciate their role in the process of breathing.

Trace the journey of O2 and CO2 in the cells.

Familiarize themselves with the organs of breathing in other organisms such
as Earthworm, cockroach and fish and relate it to their habitats.

Analyze that exchange of gases in plants is the result of respiration (which
takes place all the time) and photosynthesis (which takes place in the presence
of light)
Cross-Curricular links
Chemistry: Cellullar processes involve interaction of molecules and compounds
in living organisms.
Chemical Equations to represent exchange of gases, O2 and CO2,
H2O.
Physics:
The role of diaphragm and chest muscles as that of an air pump.
Movements in thoracic region due to inhalation and exhalation.
Role of pressure on breathing, lung capacity, rate of breathing.
English:
Vocabulary Development
Information and Technology: Explore and making use of web links
Visual Art:
Observing and drawing diagrams.
Matrix
S No Content
Learning outcome
1.
Importance of  Understand
that
respiration
breathing is inhalation
and exhalation of air.
2.
Breathing and
Respiration
3.
Aerobic
and
Anaerobic
Respiration
Skills
 Correlate the role of O2in the
breakdown of food in order to
release energy.
 Represent the role of O2 in
respiration through a word
equation.
 Differentiate
 Hands-on-experience
between breathing
 Analyze that breathing is a
and respiration.
part of respiration physical
process
and
cellular
respiration is a biochemical
process.
 Recognize the role of  Interpret (types of respiration)
oxygen in aerobic
respiration.
 Gain knowledge that  Experiential learning (muscle
respiration can also
cramps)
occur in the absence of  Hands
on
experience.
O2.
(scientific skill)
 Differentiate between  Appreciate release of energy
aerobic and anaerobic
in the absence of oxygen
respiration
4.
Organs
of
Respiration in
Human Being
 Describe the structure
of various organs of
human
respiratory
system.
 Relate the structure of
respiratory organs to
their functions.


Careful observation.
Illustration

Appreciate the role of
various organs involved in
the process of inhalation
and exhalation to their
functions.
5.
Mechanism of
Breathing
6.
The process of
cellular
respiration.
7.
Breathing
in
other animals
Ex: Earthworm,
Cockroach, Frog
and Fish
Exchange
of
gases in plants.
8.
 Investigate the role of  Visualization
various organs in the  Experimental skill. (learning
mechanism
of
by doing)
breathing.
 Trace the journey of O2  Making connections between
and CO2in the body
nutrition and respiration
cells.
 Realize how energy is released
 Define cellular
by oxidation of food in the
respiration
cells
 Analyze that breathing is a
 Comprehend the steps
part of respiration physical
that occur in cellular
process
and
cellular
respiration.
respiration is a biochemical
process.
 Familiarise
with  Relate the organs of breathing
process of breathing
of different organisms to their
in animals living in
respective habitat.
different habitats.
 Describe the
 Critically analyze that plants
process of
do not have complex organs
respiration in plants.
for respiration.
 Analyze
that  Realize that photosynthesis
exchange of gases in
and respiration takes place
plants is the result
simultaneously in the
of respiration (which
presence of light whereas at
takes place all the
night only respiration takes
time)
and
place.
photosynthesis
(which takes place in
the presence of
sunlight)
Respiration in Organisms
Teacher Notes
This unit deals with respiration, a vital process for living organisms.
It focuses on the fact that respiration is not the same as breathing.
The process of respiration includes breathing & release of energy. It
highlights the difference between aerobic and anaerobic respiration and
also appropriately describes the anatomy and physiology of the human
respiratory system. Through this unit the learners will be exposed to the
process of breathing in animals living in different habitats. This unit will
also deal with exchange of gases in plants and highlight the same during
photosynthesis and respiration.
Make a web chart of teaching points keeping in mind, the learning
outcomes at the learners level of experience and comprehension.
Web Chart
Respiration in Organisms
Give an opportunity to the learners to recall that respiration is an
important characteristic feature of living organisms. Allow the learners
to discuss the importance of respiration and ask if this is the same as
breathing.
Ask them if they have noticed the chest movements during the
process of breathing and also ask them what do they do to inflate a
balloon?
Before concluding from their answers, give them an activity
(Activity I) through which they will associate inflating a balloon while
they exhale during breathing. Ask them to do it 3-4 times and experience
the process of inhalation and exhalation.
Breathing
Release of energy
Aerobic
Respiration
Respiratory system in Humans




Organs of breathing
Physiology of respiratory system
Mechanism of breathing
Cellular respiration
(Release of energy)
Anaerobic
Breathing in other organisms
Animals
* Soil - Earthworm
* Land – Insects
* Amphibious – Frog
* Water – Fish
Plants
Respiration & exchange of
gases
Organize a discussion in the class so that the learners share among
themselves their view point on the change in the number of times they
breathe while performing various activities such as cycling, swimming,
jogging etc.
Give them Activity 2 and ask them to fill up the worksheet that
follows. Inform them that one time inhalation and one time exhalation
together should be counted as one breath. Ask each learner to count
the number of times he/she breathes in one minute, after performing
the activity according to the instructions given in the table in TSSM. Let
them share their observation in the class. Also let them announce in
which activity the count is highest or lowest. Introduce and define the
term rate of breathing.
As all the learners are aware that the exhaled air contains carbon
dioxide and water vapours, give them the apparatus to device an activity
(activity 3) to prove that exhaled air contains carbon dioxide.
Give them a hint that carbon dioxide turns lime water milky.
Thereafter, they will conclude that exhaled air contains carbon dioxide.
Ask the learners if they have experienced or seen anyone cleaning
spectacles or any glass surface by blowing on it and wiping it. Give them
hands-on-experience by asking them to blow on the surface of a mirror
(Activity 4). Summarize the observation by concluding that the mirror
becomes hazy because there is condensation of water vapour into small
droplets of water. This proves that exhaled air contains water vapour.
Ask the learners what they understand by the terms breathing and
respiration. Based on their responses, connect the process of breathing
with the utilization of oxygen to break down food, to release energy.
Facilitate the learners to conclude that breathing is a part of respiration.
Explain to the learners that release of energy takes place in every
cell, as breakdown of food takes place with the help of oxygen in every
cell. Now define the term cellular respiration.
Introduce the term ATP as energy rich molecules released as a
result of cellular respiration. Give them the expanded form of ATP.
Conclude by differentiating ‘breathing’ as a physical process,
merely a gaseous exchange; from ‘cellular respiration’ as a biochemical
process that involves oxidation of food to release energy.
Aerobic Respiration
Introduce the concept of aerobic respiration by demonstrating an
experiment to show that organisms breathe in the presence of air.
Take the example of germinating seeds to prove that they consume
only oxygen from the air they breathe in.
Set up the experiment by taking few KOH pellets or solution in a
micro test tube. Suspend it in the conical flask with a string and attach it
to the rubber stopper. KOH absorbs carbon dioxide from the air in the
conical flask and the carbon dioxide exhaled by the germinating seeds.
Give an opportunity to the learners to observe the rise in the level
of the coloured water in the delivery tube dipped in the beaker. Draw
their attention to the set up as well as the diagram of the set up given in
the TSSM.
Ask them the reason for the rise in the water level. You might be
able to elicit the answer, if not, explain that it is due to the partial
vacuum created in the conical flask. Reason out with them that this
partial vacuum is created because oxygen present in the air in the conical
flask is inhaled by the seeds and the carbon dioxide as mentioned earlier
is absorbed by the KOH. This creates vacuum because of which the
coloured water is sucked into the delivery tube. You could correlate the
rising of the water with the suction pressure.
Teacher Guidelines
1. Soak gram seeds in water overnight. Remove them the following day
and wrap them up in a damp cloth and leave it in a covered container.
2.
3.
4.
5.
After 2 to 3 days when the seeds begin to germinate, they are ready
for the experiment.
Take a conical flask and put the germinating seeds in it and cover it
with a rubber stopper with single hole. Suspend a tiny test tube
containing KOH solution with a thread before fixing the stopper.
Take a delivery tube bent in ‘U’ shape and dip one end into the
coloured water, contained in a beaker.
The other end passes through the rubber stopper.
The set up must be made air tight using Vaseline to seal the mouth of
the conical flask.
PRECAUTIONS:
1.
2.
3.
4.
Care should be taken to keep the germinating seeds moist at all times.
The apparatus should be made absolutely air tight.
The delivery tube should be dipped in water.
Facilitate the learners to conclude that germinating seeds utilize
oxygen to breathe.
5. Define Aerobic respiration and Introduce the term Aerobes for
organisms that need oxygen for respiration.
Anaerobic Respiration
Ask the learners if they can think of a living organism that respires
in the absence of oxygen.
Elicit answers from them learners and demonstrate with an
experiment (activity 5) that organisms such as yeasts, respire in the
absence of oxygen.
Follow the procedure given in the TSSM and note precautions given
below:PRECAUTIONS:
1. The test tube containing yeast in glucose solution must be kept in a
water bath maintained at 37°C.
2. Leave the set up for 24 hours at least.
It may be noted that alcohol escapes very quickly when the cork is
removed. Hence you may not be able to smell alcohol.
Represent the respiration in yeast in the form of a word equation.
Define the term anaerobic respiration and introduce the term
fermentation as anaerobic respiration in yeasts. Also make a contrast
between aerobes and anaerobes by using the term anaerobes for
organisms that respire in the absence of oxygen.
Draw the attention of learners that anaerobic respiration can occur
in humans also and recall if they have ever experienced muscle cramps
while running a race or playing. Ask them to observe the pictures in
TSSM. Reason with the learners that during heavy exercises the body
needs extra energy, for which more oxygen is required. Explain to them
that to get that required energy the muscle cells break down glucose
partially into lactic acid, releasing some energy. Accumulation of lactic
acid in the muscle cells leads to cramps. Relate it to the fact that this
release of energy takes place in the absence of oxygen, hence known as
anaerobic respiration.
Represent this in the form of a word equation also. Advice the
learners that we can get rid of cramps by hot water bath or massage as
this improves blood circulation thereby increasing supply of O2 to
breakdown lactic acid completely into carbon dioxide and water.
After having dealt with Aerobic and Anaerobic respiration take up the
detailed study of the respiratory system of the humans.
Human Respiratory System
Have a brainstorming session and elicit some information about
the organs of breathing in humans. List the organs in the right sequence.
Describe the structure of the organs and relate it to their functions as
mentioned in the TSSM. Use illustration and refer to video clips
mentioned, to reinforce the understanding of the learners.
Emphasize to the learners the role of hair and mucous present in
the nostrils and perform an activity (Activity 6) to indicate the right way
to breathe. With the help of Worksheet 1 that follows, they will be able
to practice the right way to breathe.
Bring the attention of the learners to the diagram of the respiratory
system in humans. Tell them to trace the path of the air from the nose,
through the trachea, bronchi, bronchioles and alveoli in lungs and into
the body cells.
Show them the videos (video links given in TSSM) of the
mechanism of breathing and the illustration given in the TSSM to bring
out the process of inhalation and exhalation.
Ask them to do an activity (Activity 7) to understand that the chest
size increases during breathing. Through this activity make the learners
realize that there is a variation in the chest size of different individuals.
To facilitate the learners to comprehend the mechanism of
breathing better, give them hands-on-experience (Activity 8) by asking
them to make a simple model that simulates the mechanism of
breathing in humans. For the recapitulation of the process of inhalation
and exhalation ask them to fill up Worksheet 2.
Take them through the journey of inhaled air and exhaled air and
emphasize that though the path of their movement is the same yet the
direction in which the inhaled air and exhaled air move is opposite to
each other. Reinforce the same through Worksheet 3.
You have now reached a stage when you can rightly relate the
process of nutrition with the release of energy during respiration.
With the help of the diagram of alveoli with a blood capillary given
in TSSM, explain how oxygen diffuses into the blood capillaries and
reaches the body cells. You can explain that it is here that the assimilated
food breaks down (gets oxidized) to release energy. Clarify to the
learners that since the energy is released in the body cells, this step of
respiration is known as cellular respiration.
Emphasize once again that process of cellular respiration is a
chemical process and breathing is a physical process. Also give a word
equation to sum it up.
Explain the keywords giving their appropriate definition and usage
to facilitate vocabulary development. Draw the attention of the
learners to the process of breathing in other animals. To arouse their
curiosity ask them to brainstorm how the animals of different habitats
breathe. Ask the learners how animals living in moist soil breathe. Take
the example of earthworms and explain that they breathe with the help
of moist skin.
Compare the breathing surface of earthworms to that of the insects
that have a hard body cover (exoskeleton). Take the example of a
cockroach which has holes on the sides known as spiracles through
which the air enters into the tracheal system and diffuses into the body
cells. Ask them to observe the picture of an insect larva given in TSSM to
notice the spiracles.
It will be interesting to take up the example of frog to find out from
the learners how does it breathe. Let them recall that the frog lives in
water and on land as it is an amphibian. Make them realize that the
amphibians are a group of animals showing the transition from aquatic
life to life on land signifying an evolutionary trend hence they need to
breathe with the help of different organs while on land and in water.
Introduce to them; lungs and buccal cavity as breathing organs when
they are on land (The term buccal cavity may be explained to them with
its significance). Also tell them that oxygen diffuses through their moist
and slimy skin while they are in water.
Ask the learners if fish can survive out of water. Draw their
attention to the structure of gills and how these facilitate gaseous
exchange. Let the learners realize that the body of fish is covered with
scales therefore air cannot diffuse into the body through the surface
unlike in case of frog. Conclude by telling the learners that the organs of
breathing of aquatic animals are not the same as those of amphibians.
Summarize by asking the learners to analyze and correlate that the
organs of breathing in different animals depend on their habitat.
Respiration and Exchange of gases in Plants
Review the fact that plants also respire since they are living
organisms. Highlight the characteristics features of plants while stating
that they do not have complex organs for respiration. Emphasize that
plants do not make breathing movements but gaseous exchange takes
place in all organs of the plant body by simple diffusion. Let the learners
correlate that exchange of gases in plants is the result of respiration
(which takes place all the time) and photosynthesis (which takes place in
the presence of light)
Let the learners realize that photosynthesis and respiration takes
place simultaneously in the presence of light whereas at night only
respiration takes place.
Conclude the study of this unit by summarizing that respiration is
an important biological process in all living organisms and it is through
respiration that the living organisms get the much needed energy for
their survival.
RUBRIC: ASSESSMENT OF LEARNING
Parameter
Learner is able to
Comprehend
the
concept of inhalation
and differentiate it
from exhalation
O2 breaks food to
release energy
Beginning
(1)
Text book based
Partially Proficient (2)
In own words
Proficient
(3)
Use synonyms, other
terms to express
Exemplary
(4)
Uses related terms and
other examples to
convey concept
Differentiate between
breathing
and
respiration
In brief
Uses given examples
to
explain
and
differentiate
Uses examples with
explanation
to
differentiate
Uses specific but
different words to
explain differences
Just names without
elaboration
Mentions
examples
elaborates
few
and
Mentions
more
examples with better
explanation
Structure
and
functions
of
Respiratory System in
Man
Investigate role of
organs
Incomplete labeling of
diagrams and just
names parts from text
Completes diagrams
well, with complete
labeling
Discusses functions of
parts
with
more
examples
Barely
In brief
Trace journey of CO2
and O2
Comprehend steps of
cell respiration
Understands
respiration in other
organisms
Incomplete
Nearly complete
Uses
observation
based examples to
explain the role of
organs
Discuss the pathways
and
steps
in
respiration
Focused on details
Able
to
devise
experiments to show
the process
Uses specific words to
explain functions and
illustrates well and
clearly
Uses related examples
to explain
Text book based
In own words
Discuss and elaborate
with more examples
Respiration in plants
Compare
Photosynthesis
and
Respiration
In brief
Uses a few examples
to compare the two
processes
Discuss
the
two
processes in detail
Define respiration
Respiration
–
biochemical process
Breathing
–
Physiological process
Differentiate between
aerobic and anaerobic
respiration
a
Uses specific words to
convey the concept of
transportation
Uses more examples
and
makes
connections with more
organisms
and
compares
Uses related terms and
examples to bring out
differences
clearly
between the two
processes
CBSE-i
Class VII – Biology
Unit: 15
Respiration in Organisms
Teacher Student Support Material
(TSSM)
Teacher Student Support Material (TSSM)
1. Introduction
2. Importance of Respiration
3. Breathing and Respiration
a. Breathing
 Activity 1
 Activity 2
b. Breathing rate
 Activity 3
 Activity 4
c. Is breathing and Respiration the same?
4. Aerobic and Anaerobic Respiration
a. Aerobic
 Activity 5
b. Anaerobic
 Activity 6
5. Respiratory System of Humans
a. Nose
 Activity 7
 Worksheet 1
b. Wind pipe/Trachea
c. Lungs
d. Bronchi/Bronchioles
6. Mechanism of Breathing
 Activity 8
 Activity 9
 Worksheet 2
a. Journey of Oxygen and Carbon dioxide in body cells
 Worksheet 3
b. How is Energy consumed?
7. Breathing in Other Animals
a. Earthworm
b. Cockroach
c. Frog
d. Fish
 Worksheet 3
8. Respiration and Exchange of gases in Plants
9. Post Content Worksheets
10. Glossary
11. E – Resources
RESPIRATION IN ORGANISMS
Introduction
Respiration is a process that involves exchange of oxygen from air
with carbon dioxide produced in living organisms. This unit is meant to
investigate the importance of respiration for living organisms. Through
this unit the learners will be able to correlate the structure of respiratory
organs with their functions and also differentiate between breathing and
respiration.
This unit will also empower the learners to analyze the link
between respiration and the utilization of oxygen to breakdown the
assimilated food in order to release energy. It will also include the study
of the process of breathing in other organisms such as earthworm,
cockroach, and fish. It will provide the learners with enough
opportunities/occasions to explore process of respiration and
significance of exchange of gases in plants.
Importance of Respiration:
Recall from what have you studied in your previous class that
respiration is a characteristic feature of living organisms. It involves
two main processes- breathing and energy release. The oxygen taken
in during breathing acts on assimilated food in the cells to release
energy.
Breathing:
Breathing is the process of inhalation and exhalation of air. Let us
carefully observe breathing by performing an activity.
Activity 1:
To experience the process of breathing.
Hold a deflated balloon.
Take a deep breath. Bring
the opening of the balloon to
your mouth and exhale
(blow out) in to the balloon.
We will notice the balloon
gets inflated when we blow
into its mouth.
Thus we observe and experience the process of taking in and out
air
during this
activity?
http://www.merckmanuals.com/home/lung_and_airway_disorders/biology_of_the_l
ungs_and_airways/control_of_breathing.html
Do the following activity, note down your observations and fill
up the number of times you breathe. Count one breath as one time
inhalation and one time exhalation.
(One inhalation + one exhalation = 1 breath)
Activity: 2
Rate of breathing varies with different types of activities in an organism
S no
Activity
No of times you breathe in a minute.
1.
After resting for 10 minutes
2.
On the spot jogging for 5 minutes
3.
After running for 2 minutes.
4.
After cycling for 10 minutes.
5.
After climbing stairs for two floors.
Observation: You will notice that the number of times you breathe in
a minute varies with the nature of the activities you perform.
Conclusion: We breathe faster when we perform strenuous physical
activities.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Breathing Rate
The number of times a person breathes in a minute is called
breathing rate. On an average, an adult human being breathes 15-18
times in a minute. On exercising the breathing rate can go up to 25 times
per minute. The rate of breathing is not constant but varies during
different activities.
We have learnt in our previous classes that exhaled air contains
carbon dioxide. Let us perform an activity to prove the same.
Activity: 3
To prove that the exhaled air contains Carbon dioxide
Think of an experiment you can perform to prove that carbon
dioxide is given out as a result of exhalation. You are given the
following items. Lime water, a glass, a straw.
The carbon dioxide present in
the exhaled air turns the
colour of lime water milky.
This proves that exhaled air
contains carbon dioxide.
you must have noticed
someone,
cleaning
their
spectacles by blowing on the
lens and then wiping it? We will notice when we do this, the lens
becomes clean.
Let us try to find out the reason for this.
Exhaled Air contains water vapours
Activity 4: (Group activity)
To prove that the exhaled air contains water vapours
Stand in front of a mirror and breathe out. Mirror becomes hazy.
This is because there is condensation of water vapours into small
droplets of water. This proves that exhaled air contains water vapours.
Is Breathing and Respiration the same?
The term respiration is not the same as breathing. Respiration
includes breathing and break down of assimilated food with the help of
O2 to release energy. Release of energy from organic compounds in cells
is in the form of ATP (energy rich molecules). ATP (Adenosine Tri
Phosphate) is the molecule which directly provides energy to various
biological reactions that take place in our body. This process takes place
in every cell of the body hence is known as Cellular Respiration.
So breathing is a physical process during which there is no oxidation
of food. Breathing is a physical process which is simply exchange of gases
whereas cellular respiration is a biochemical process which involves
breakdown of food (oxidation of food) to release energy.
Therefore we can conclude that what we generally call respiration
actually includes both breathing and cellular respiration.
Aerobic and Anaerobic Respiration
Aerobic Respiration:
Observe the demonstration of an experiment showing that living
organism breathes.
Activity: 5
Apparatus required: conical flask, bent tube, cork, Vaseline, coloured
water, germinating seeds.
Procedure: Take some germinated seeds in a conical flask. Fix the
delivery tube bent in “U” shape with a cork to the conical flask. coloured
water in a beaker. Put KOH (potassium hydroxide) pellets or solution in
a small test tube and suspend with a thread tied to the rubber stopper
in the conical flask as shown in the diagram.
Keep the other end of the delivery tube dipped in coloured water.
Make the apparatus air tight by using Vaseline. After some time the
water level will rise.
You will observe that there is an increase in the level of coloured
water of the delivery tube which is immersed in the beaker containing
water.
Inference: This happens because the oxygen which is present in the
conical flask is utilized by the germinating seeds and they release carbon
dioxide. This carbon dioxide is absorbed by the potassium hydroxide and
partial vacuum is created. The coloured water rises to fill up the vacuum
space. Thus this experiment shows that living organisms such as
germinating seeds respire.
Suggestion: this experiment may be repeated by replacing germinating
seeds with flower buds.
This experiment shows that germinating seeds take in oxygen and give
out carbon dioxide.
The process of respiration that utilizes oxygen is known as aerobic
respiration.
In the process of aerobic respiration, breakdown of food/glucose
takes place in the presence of oxygen releasing CO2, water vapour and
energy. Organisms that carry out aerobic respiration are called aerobes.
This process is summed up in a word equation below:
food
with the use Oxygen
CO2+ H2O + Energy
Anaerobic Respiration:
List living organisms that respire in the absence of oxygen? How do
they survive?
There are some organisms like yeast, bacteria and parasites that can
survive in the absence of air. They can breakdown glucose to release
energy without using oxygen. In this type of breakdown of glucose, in the
absence of O2 very little energy is released.
Activity 6: Some organisms respire
even in the absence of Oxygen.
Observe the demonstration of
an experiment which shows, some
organisms even respire in the
absence of Oxygen. Take some sugar
solution in a boiling test tube; add
some yeast powder to that solution.
Fix the cork. Leave the test tube for two days.
Observation:
 lime water turns milky
 Smell of alcohol is noticed.
This process of respiration in yeasts can be represented by the
following word equation.
Glucose
without the use Oxygen
Ethyl Alcohol + CO2 + Energy
Industrial application of Yeast.
Yeast produces alcohol and helps
in the preparation of bread and
cheese.
Conclusion: “Yeasts convert sugar into alcohol”. The yeasts respire in the
absence of oxygen.
Organisms which carry out respiration in the absence of oxygen to
fulfill their energy needs are called Anaerobes. These organisms have the
ability to survive for longer period of time without using oxygen than
aerobes.
Thus we can say that the process of respiration that takes place in the
absence of oxygen is known as anaerobic respiration.
Observe the following pictures
Why do people get muscle cramps after heavy exercises such as cycling,
swimming or jogging for long time?
http://www.pixelatestudio.com/cycling_photos.htm
http://new-york-chiropractor.blogspot.in/2010/12/so-you-were-playing-sports-and-your-leg.html
http://en.topictures.com/physical%20therapist
During heavy exercises, fast running or weight lifting the demand
for energy is very high, but the supply of oxygen is very limited and the
muscle cells have to respire without adequate supply of oxygen. During
this type of respiration, energy released is very less as compared to
aerobic respiration.
This can be represented by the following equation.
Glucose
in the absence of Oxygen
Lactic acid + Energy (in the muscle cells)
The muscle cramps formed after heavy exercises are because of
partial breakdown of glucose into Lactic acid which accumulates in
muscles.
Relief from cramps
We can get relief from cramps by hot water
bath or massage. This improves the blood
circulation and restores the supply of O2 resulting
in the complete breakdown of accumulated lactic
acid into CO2 and water and thus giving relief
from cramps.
By aerobic respiration
glucose
produces
38
molecules of ATP and by
anaerobic respiration the
energy yield is 2 molecules
of ATP.
Respiratory System in Humans:
Respiratory
system
facilitates
exchange of oxygen and carbon dioxide
required by the body. The respiratory
system can be divided into three parts.
 Air passages and tubes include the
nose, wind pipe, bronchi, and
bronchioles.
 Air pump includes chest cavity
containing lungs and diaphragm.
 Respiratory surface includes alveolar
lining and blood capillaries.
(Fig: Respiratory system of human being)
http://people.eku.edu/ritchisong/301notes6.htm
Organs of Respiration in Humans:
The organs of respiration are Nose, wind pipe (trachea), Lungs,
bronchi and bronchioles.
Nose: Air normally enters in to lungs through the nose. Hair in the nose
traps some of the dust particles that come along with the air. The lining
of the nose also produces mucus (a watery liquid) which keeps the air
moist and does not allow any dust particles to enter along with air.
The hair and mucus act as filters and allow clean air to pass through
the nostrils.
As the air passes along
the nasal passage, the blood
vessels beneath the nasal lining
release heat. This heat regulates
the temperature of the air before
it passes in to the lungs. That is
why in winters also the air that
we breathe out is warm.
What would happen if we breathe through our mouth? Let us do
an activity to understand the significance of correct way of breathing.
Activity 7– Inhaling air through nose and mouth
Do the following activity to experience inhaling air through nose
and mouth and fill up worksheet 7.
Inhaling air through Nose
Inhaling air through mouth
http://thebreathingman.wordpress.com/article/nose-breathing-202i29i90v7sn-41/
http://www.rxlist.com/aerospan-hfa-drug/medication-guide.htm
Worksheet 1
Way to breathe
Breathe through the nose and through the mouth each for 5
minutes and note the difference by answering the following questions
in Yes or No as applicable:
Inhaling
through nose
1. Does your throat become dry?
2. Do you feel irritation in your throat?
Now what do you advise yourself?
Inhaling
through mouth
You must not breathe through your __________(mouth/nose).
When we breathe through our mouth, there is nothing to stop the
dust particles and harmful germs to enter the throat thus causing
irritation in the throat.
-------------------------------------------------------------------------------------------
What is smokers cough?
What will happen in severe bronchitis?

What is asthma?
Wind pipe / Trachea
From the nose, the air enters
pharynx. From the pharynx the air enters
into a tube called wind pipe also known
as trachea. Trachea is a tube about 12 cm
in length and 2.5 cm in diameter in an
adult. It might be interesting to note that,
whether the air enters through the nose
or the mouth, it will pass into the wind
pipe through the pharynx.
Lungs
There is a pair of lungs in a human body, present on each side of
the chest cavity. Lungs are the main respiratory organs in our body and
are enclosed in chest cavity. This cavity is protected by the bony
structures called ribs. At the base (lower end) of the chest cavity there is
a large muscular sheet called diaphragm (Observe the diaphragm in the
picture given above), which separates the upper part (thoracic cavity) of
the body from lower part (abdominal cavity) of the body. The rib bones
are attached to the muscles. The muscles of the ribs and diaphragm
move during breathing.
http://www.cancer.umn.edu/cancerinfo/NCI/CDR269299.html
Bronchi and Bronchioles:
The wind pipe divides into
two smaller tubes called
bronchi (bronchus –
singular). Each bronchus
divides into many smaller
bronchioles.
Each
bronchus enters the lungs
and
branches
into
bronchioles. At the end of
these bronchioles are air
sacs called alveoli.
The
air
after
entering the bronchi,
reaches bronchioles and
then into alveoli (air sacs).
http://www.naturalhealthschool.com/bronchi_trachea.html
From the alveoli the air diffuses into the blood capillaries as they
are surrounded by the blood vessels. The carbon dioxide present in the
blood vessels enters the alveoli and is exhaled through the nostrils along
with water vapours.
Some people suffer from asthma. They may be allergic to some foreign materials.
These materials cause allergy and the air passages become narrower. This makes
breathing very difficult. Such a person has to use inhaler that releases chemicals to
make the muscles relax and widen the bronchioles.
http://www.nytimes.com/imagepages/20
07/08/01/health/adam/19346Normalversusasthmaticbronchiole.html
Read more on the following website:
www.health.howstuffworks.com/adam-200142.html
Mechanism of Breathing:
There are two breathing
movements
1) Inhalation
2) Exhalation
Inhalation
During inhalation:
 Inter-costal muscles contract
 Ribs move outwards and
upwards.
 Diaphragm is pulled
down into a flat
position.
 Volume of the chest
cavity increases
 Pressure inside the
lungs reduces.
Therefore air rushes into
the lungs.
Exhalation:
During exhalation:
 Rib muscles relax
 Ribs move inwards and downwards.
 Diaphragm moves up.
 Volume of the chest cavity decreases
 Pressure inside the lungs increases.
Therefore air is pushed out of the lungs.
The number of times a person
breathes in a minute is called breathing
rate. On an average an adult human being
breathes 15 – 18 times in a minute. On
exercising the breathing rate can go up to
Watch these Respiration Videos
http://www.youtube.com/watch?v=HiT621PrrO0
http://www.youtube.com/watch?v=RfCeiK0xtR0&feature=related
http://www.youtube.com/watch?v=12ddbrqpZiQ&feature=related
Activity 8:
Increase in the chest size during inhalation
Instructions:
Measure the size of your chest with a measuring tape and record your
observations. Now take a deep breath and hold it. Again measure the
size of your chest.
Study the increase in the chest size (in cm) of 4 of your classmates,
complete the following table and note the measurements.
Size of the Chest
S.No. Name of the student
Normal
After a deep Difference
Breathing breath
in size
(in cm)
(in cm)
(in cm)
You may notice the variation in the chest size among the students.
Activity 9: To understand the mechanism of breathing by a simple
model.
Take two bell jars. Take a Y shaped glass tube and fix two balloons
on each end. Insert
this Y shaped glass
tube with balloons in a
bell jar or plastic
transparent bottle as
shown in the diagram.
Tie a thin rubber
sheet around the
bottom of the bell jar.
hyperphysics.phy-astr.gsu.edu
Inhalation
Exhalation
This set up is a replica of the human respiratory system. The bell jar
is the chest cavity, the balloons are the lungs, and the rubber sheet is the
diaphragm. Pull the rubber sheet down, to show that:
i) Space in the jar increases
ii) Balloons get inflated
iii) Air enters the balloons
This is how we inhale.
If we do the reverse we will find:
i)
Space in the jar decreases
ii)
Balloons get deflated
iii)
Air leaves the balloons
This is how we exhale.
Worksheet 2:
Process of inhalation and exhalation
(A) The steps for the process of inhalation are given below. Write the
corresponding steps of the process of exhalation on the right hand
side.
Process of Inhalation





Process of Exhalation
Ribs move outwards and upwards. -------------------------------Diaphragm is pulled down
------------------------------Volume of the chest cavity increases ------------------------------Pressure inside the lungs reduces. -------------------------------Air enters the lungs
---------------------------------
(B) Observe the diagram given below.
Write the parts of human respiratory system that correspond to
the labeled parts: i), ii) & iii).
Corresponding parts of human respiratory system
i)
ii)
iii)
Journey of Oxygen and Carbon Dioxide in Body Cells:
Oxygen from the inhaled air diffuses through the walls of the alveoli
into the blood capillaries. This oxygen is carried to all cells of the body,
where it breaks down (oxidizes) the assimilated food to release energy.
Carbon dioxide is carried from body cells into the blood capillaries.
From the blood capillaries it diffuses into alveoli. It is then pushed out
through bronchioles, bronchi, and exhaled through the nostrils. Blood
moves into the capillaries very quickly.
web.med.unsw.edu.au
Work sheet 3:
Trace the path of oxygen and carbon dioxide
Trace the path of oxygen and carbon dioxide in the table given below.
Write the names in correct sequence of the two paths. Use red colour
for tracing path of oxygen and blue colour for carbon dioxide. Choose the
appropriate words from the list provided below, the first step of each
path is done for you.
trachea, alveoli, body cells, bronchioles, bronchi, blood capillaries, nose
Path of oxygen
1
Path of carbon dioxide
Nose
1. Body cells
2 --------------
2 -------------
3----------------
3 ----------------
4 ----------------
4 ----------------
5 -----------------
5 ---------------
6 -----------------
6 ----------------
7 ----------------
7 -----------------
---------------------------------------------------------------------------------How is Energy Produced?
We have studied that the digested food substances enter the cells of the
body through the blood. The oxygen of the air enters the blood from
alveoli.
The blood carries the oxygen to the cells of the body during its
circulation. The oxygen acts upon the food present in the cells of the
body to produce energy and release carbon dioxide.
The change can be summarized as:
Food + oxygen
CO2(carbon dioxide) + Energy + Water vapours
Since the energy is released in the cells, the process is known as cellular
respiration.
Cellular Respiration is a Biochemical Process.
Breathing in other animals:
We know that animals obtain energy by the oxidation of assimilated
food. We have seen that respiration needs continuous supply of
oxygen to break down the food and carbon dioxide is released during
respiration. Let us see how the exchange of gases takes place in some
other animals.
Earthworm:
The earthworms live in damp
soil. Gaseous exchange takes place
through their moist skin. In these
earthworms, the thin and moist
skin is richly supplied with blood
vessels (capillaries) which absorb
oxygen from the atmosphere and
release
carbon
dioxide.
Earthworms breathe through their
moist skin
Insects:
Air reaches various parts of the
body of an insect through an
elaborate system of branching tubes
called tracheae. The tracheae open
outside through holes called
spiracles. Most of the tracheal tubes
run along and across the body and
divides
into
smaller
called
tracheoles.
Oxygen enters tracheal system
through the spiracles and diffuses
into the body cells. Carbon dioxide diffuses out of the body cells into
trac
Larva of an insect
heal system and is carried out of the body through the spiracles.
http://www.entomology.umn.edu/museum/projects/Interactive_Keys/Intro_tutorial/GLOSSARY/Spiracles.html
Frog:
Frogs can live both in water and on land, therefore, they can breathe
both on land and in water. They have a pair of lungs and a large
opening of the mouth (buccal cavity) to enable them to breathe on
land. They have a moist, slimy skin to enable them to breathe in water.
Since they live in amphibious habitat they are known as amphibians.
Fish
Fishes absorb dissolved oxygen present in water by gills. Gills
are projections of the skin and are richly supplied with blood vessels
for exchange of gases. A fish gulps water through the mouth and
forces it between the gills on each side of its neck. As water flows
across the gills, the oxygen in it gets diffused into the blood stream.
At the same time carbon dioxide in the blood stream diffuses into the
water.
Organs of breathing of different animals help them to breathe in
their specific habitats.
So we notice animals living in soil such as earthworm breathes
through moist skin, land animals such as insects breathe through
spiracles and aquatic animals such as fish breathe through gills. Animals
such as frogs that can live on land and in water have lungs to breathe
while on land and moist skin to breathe while in water.
We can conclude that animals of different habitats have different
organs of breathing.
Respiration in Plants:
Plants do not make breathing movements to exchange oxygen and
carbon dioxide. They rely on the process of diffusion through which
the gases move in and out of their cells and their body.
http://evolution.berkeley.edu/evolibrary/article/mcelwain_02
Exchange of gases in Plants
Like all other living organisms, plants also respire for their survival
for which they take in oxygen from the air and give out carbon dioxide.
Plants do not have any organ system or organs for breathing. It is
interesting to note that in plants exchange of gases takes place by simple
diffusion directly into each cell through the openings present in
epidermis called stomata.
Even the stems have openings called lenticels that help in the
exchange of gases. Lenticels are present in older roots also. These pores
on leaves, stems and roots allow oxygen, carbon dioxide and water
vapours to come in and out of the plant body. Leaves and stems
exchange gases from the air they are exposed to whereas roots which
grow under the soil take up air from the air spaces present between soil
particles.
What would happen if
a potted plant is
overwatered?
http://preuniversity.grkraj.org/html/4_PLANT_AND_WATER_RELATIONSHIP.htm
Recall that during photosynthesis, plants take in carbon dioxide and
give out oxygen. We also know this process takes place only in the
presence of light.
Now we also know living organisms, including plants, take in
oxygen and give out carbon dioxide during respiration. This process takes
place throughout the life of the organisms.
We can conclude that exchange of gases through the stomatal
pores is the due to respiration and photosynthesis during the day,
whereas at night, it is only due to respiration.
So we have learnt that respiration is an important biological
process in all living organisms. It is through respiration that the living
organisms get the much needed energy for their survival.
POST CONTENT WORKSHEET 1
1) List the similarities and differences between aerobic and anaerobic
respiration.
2) Define breathing rate?
3) Why do we sneeze when we inhale dust?
4) Define the terms inhalation and exhalation.
5) Why do we breathe faster after running?
6) Why do we yawn when we are sleepy?
7) Give simple word equations for the following types of respiration:a) aerobic respiration
b) anaerobic respiration in yeast
c) anaerobic respiration in the muscles of man.
8) Why do we feel hungry after a vigorous exercise session?
9) Draw and label the parts of the human respiratory system.
10) Describe in brief the mechanism of breathing.
11) Depict mechanism of breathing diagrammatically.
12) Give an experiment to prove that we exhale air with CO2 and water
vapours.
13) Complete the statements given below by choosing the most
appropriate word from the list given below:
Diaphragm, Ribs, carbon dioxide, inwards, outwards, upwards, downwards,
15-18 times per minute, 40 times per minute, increases, decreases
a) ------------------is located at the base of the chest cavity.
b) During heavy exercises, we get cramps in the legs due to the
accumulation of -------.
c) Normal range of breathing rate in a healthy adult at rest is---------- per
minute.
d) During inhalation, the ribs move --------- and --------------.
e) The size of the chest cavity ------------- during inhalation.
14) What is the full form of ATP?
POST CONTENT WORKSHEET 2
1) State if the following statements are true or false (T/F):a) Plants carry out respiration only during the day. (T/F)
b) Photosynthesis takes place only during the day. (T/F)
c) Frogs breathe both through lungs and skin.
(T/F)
d) Cockroaches respire through lungs
(T/F)
2) Explain briefly how insects respire?
.
3) Earthworms have moist skin. Why?
4) How do gills help fishes to breathe under water? Also draw diagram
to show gills in a fish.
5) What are stomata? Where would you look for them?
6) Explain how do roots breathe?
7) What will happen if a potted plant is flooded with water?
8) Why do we use flower bud/ germinating seeds in the experiment
which shows respiration occurs in living organisms?
Glossary
Toxic – poisonous and harmful to people
Diffusion – random movement of molecules (liquid or gas) resulting in
mixing in another substance
ATP - Energy rich molecule (full form - Adenosine Tri Phosphate) in the
cells that lets the energy go from it for chemical reactions
Biochemical - relating to the chemical substances and processes in living
organisms
Vacuum - space completely empty of all substances including air or gases
Inhalation - taking in (inhale) air during breathing.
Exhalation - giving out (exhale) air during breathing
Metabolism - biochemical processes in cells necessary for life, all the
chemical processes by which cells produce the energy and substances
necessary for life
Fermentation - a chemical change due to the action of Yeast or Bacteria
often changing sugar to alcohol
Anaerobic - a process or a happening that does not need oxygen.
Aerobic respiration - the process of respiration that requires oxygen in
order to release energy by the breakdown of food
Alveoli – The air sacs through which the air diffuses into and out of blood
capillaries from bronchioles located in the lungs.
E – Resources
http://www.getbodysmart.com/ap/respiratorysystem/zonesdivisions/tutorial.html
http://www.getbodysmart.com/ap/respiratorysystem/menu/menu.html
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/
animation gas_exchange_during_respiration.html
Gas Exchange Animation
http://www.youtube.com/watch?v=HiT621PrrO0
Respiration Video
http://www.youtube.com/watch?v=RfCeiK0xtR0&feature=related Respiration Video
http://www.youtube.com/watch?v=12ddbrqpZiQ&feature=related Respiration Video
http://www.youtube.com/watch?v=Mf8xTqfspp4 Diaphragmatic breathing animation
http://www.daviddarling.info/encyclopedia/Respiratory_system.html Gas Exchange in
Lungs
http://www.health.com/health/library/mdp/0,,tp10237,00.html Gas Exchange in Lungs
http://www.tutorvista.com/content/biology/biology-iv/respiration-animals/breathingmechanism.php
Experiment on Breathing Mechanism
http://www.ischool.zm/es/STUDY%202.html
Experiment on Breathing Mechanism
http://www.merckmanuals.com/home/lung_and_airway_disorders/biology_of_the_lun
gs_and_airways/control_of_breathing.html
Diaphragm movements with breathing
http://www.pixelatestudio.com/cycling_photos.htm
Cyclist
http://en.topictures.com/physical%20therapist
Muscular Pain in legs
http://thebreathingman.wordpress.com/article/nose-breathing-202i29i90v7sn41/
Breathing from Nose
http://www.rxlist.com/aerospan-hfa-drug/medication-guide.htm
Breathing from Mouth
http://people.eku.edu/ritchisong/301notes6.htm
Respiratory System
http://www.naturalhealthschool.com/bronchi_trachea.html Trachea
http://www.cancer.umn.edu/cancerinfo/NCI/CDR269299.htm
Diaphragm
http://www.youtube.com/watch?v=HiT621PrrO0
Respiration Video
http://www.youtube.com/watch?v=RfCeiK0xtR0&feature=related Respiration Video
http://www.youtube.com/watch?v=12ddbrqpZiQ&feature=related Respiration Video
http://preuniversity.grkraj.org/html/4_PLANT_AND_WATER_RELATIONSHIP.html
Absorption by roots
***