Class 7 Science Notes for Respiration in Organisms
Download Class 7 Science Notes for Respiration in Organisms in PDF format. Access concise and easy-to-understand short notes for 7th Class from aglasem.com to help you excel in your studies.
More Detail
Latest News
Finished viewing? Save it for later —
Download Class 7 Science Notes for Respiration in Organisms (PDF · 8 pages)Downloaded 65 times
About Class 7 Science Notes for Respiration in Organisms
Class 7 Science Notes for Respiration in Organisms is available here for free download. Published by AglaSem for Class 7, this notes can be viewed online or downloaded as a PDF (8 pages). Candidates preparing for Class 7 can use Class 7 Science Notes for Respiration in Organisms to understand the exam pattern, the type of questions asked, and the overall difficulty level.
Frequently Asked Questions
How can I download Class 7 Science Notes for Respiration in Organisms?
Open this page and click the Download button to save Class 7 Science Notes for Respiration in Organisms as a PDF. It is completely free on AglaSem Docs.
Is Class 7 Science Notes for Respiration in Organisms free to download?
Yes. Class 7 Science Notes for Respiration in Organisms can be viewed online and downloaded as a PDF free of cost on AglaSem Docs.
How many pages does Class 7 Science Notes for Respiration in Organisms have?
Class 7 Science Notes for Respiration in Organisms contains 8 pages, which you can read online or download together as a single PDF.
Where can I find more Class 7 study material?
You can find more Class 7 question papers, sample papers, syllabus, and answer keys on AglaSem Docs.
Class 7 Science Notes for Respiration in Organisms – Text
Read the full text of this notes below — useful to quickly search, copy and reference the content online without downloading the PDF.
📄 View text version (10 pages)
Page 1
NOTES
CLASS 7
SCIENCE
Study Material
DOWNLOAD PDF
CLASS 7
SCIENCE
Study Material
DOWNLOAD PDF
Page 2
RESPIRATION IN ORGANISM
Why do we respire?
All the living organisms are made up of small microscopic units called the cells.
These cells have different functions to perform in these organisms such as digestion,
respiration, transportation and excretion.
The cells can perform this function only if they get the energy to do so.
Hence, all living organisms need food which gives them the required energy.
The energy present in the food gets released when the organisms respire or breathe.
How food helps us in gaining energy?
As we breathe, we take in the air that contains oxygen in it and breathe out air which
contains carbon dioxide. This oxygen when transported to our cells helps in breaking
down the food and we get energy.
What is cellular respiration?
Cellular respiration can be defined as the process in which the food that we eat is
broken down inside the cells which results in the release of energy. All the cells in
living organisms undergo cellular respiration.
The cellular respiration takes place in a cell organelle called mitochondria.
The oxygen that an organism breathes in reacts with the carbohydrates (glucose)
present in the food and results in the release of carbon dioxide, water and energy.
Types of respiration-
Aerobic Respiration Anaerobic Respiration
1. This kind of respiration takes place in 1. This type of respiration happens in the
the presence of oxygen. cells in the absence of oxygen.
2. It leads to release of a high amount of 2. It results in a low amount of energy.
energy in living organisms.
3. Human beings and many other animals 3. Yeast and sometimes human beings
undergo aerobic respiration. undergo anaerobic respiration.
4. Carbon dioxide and water are also 4. Animal muscle cells release lactic acid
released in aerobic respiration. and Yeasts release ethanol and carbon
dioxide in anaerobic respiration.
Anaerobes:
Organisms that can exist in the absence of air are called anaerobes.
They undergo anaerobic respiration hence can get energy even without oxygen.
For example, Yeasts. These are unicellular organisms that exist in the absence of
oxygen as well.
KVS ZIET CHD Class VII-Science 2023-24 Page 33
Why do we respire?
All the living organisms are made up of small microscopic units called the cells.
These cells have different functions to perform in these organisms such as digestion,
respiration, transportation and excretion.
The cells can perform this function only if they get the energy to do so.
Hence, all living organisms need food which gives them the required energy.
The energy present in the food gets released when the organisms respire or breathe.
How food helps us in gaining energy?
As we breathe, we take in the air that contains oxygen in it and breathe out air which
contains carbon dioxide. This oxygen when transported to our cells helps in breaking
down the food and we get energy.
What is cellular respiration?
Cellular respiration can be defined as the process in which the food that we eat is
broken down inside the cells which results in the release of energy. All the cells in
living organisms undergo cellular respiration.
The cellular respiration takes place in a cell organelle called mitochondria.
The oxygen that an organism breathes in reacts with the carbohydrates (glucose)
present in the food and results in the release of carbon dioxide, water and energy.
Types of respiration-
Aerobic Respiration Anaerobic Respiration
1. This kind of respiration takes place in 1. This type of respiration happens in the
the presence of oxygen. cells in the absence of oxygen.
2. It leads to release of a high amount of 2. It results in a low amount of energy.
energy in living organisms.
3. Human beings and many other animals 3. Yeast and sometimes human beings
undergo aerobic respiration. undergo anaerobic respiration.
4. Carbon dioxide and water are also 4. Animal muscle cells release lactic acid
released in aerobic respiration. and Yeasts release ethanol and carbon
dioxide in anaerobic respiration.
Anaerobes:
Organisms that can exist in the absence of air are called anaerobes.
They undergo anaerobic respiration hence can get energy even without oxygen.
For example, Yeasts. These are unicellular organisms that exist in the absence of
oxygen as well.
KVS ZIET CHD Class VII-Science 2023-24 Page 33
Page 3
As a by-product, they release ethanol and carbon dioxide. That is why they are us ed to
make wine and beer. This is called as alcohol fermentation.
Anaerobic respiration in human beings
Sometimes muscles of human beings can respire without oxygen.
This generally happens when we undergo a heavy exercise such as running,
weightlifting, cycling or walking for a longer duration.
In such situations, the muscles require more energy and the supply of oxygen is not
enough.
Hence anaerobic respiration takes place in the muscles.
As a result of muscles also produce lactic acid along with energy.
This lactic acid accumulates in the muscles and causes cramps.
That is why we often feel cramps while we do heavy exercises.
In order to get relief from cramps, we can take a hot water bath or massage our
muscles.
This is so because hot water bath or massage improves the blood circulation in the
muscles.
As a result, the oxygen reaches the cells easily which breaks on the lactic acid into
carbon dioxide and water.
Breathing:
Breathing can be defined as a process in which organisms, with the help of their
respiratory organs, take in the oxygen-rich air present in the surroundings and release
out air that contains high amount of carbon dioxide in it. Breathing occurs
continuously in the organisms.
Inhalation is the process of taking the air that contains oxygen inside the body.
Exhalation is a process of releasing out air that contains carbon dioxide out of the
body. Inhalation and exhalation take place alternatively in the breathing process.
Breathing rate can be defined as the number of times a person breathes in a minute.
A breath can be defined as an inhalation followed by an exhalation.
The breathing rate is not always constant in human beings. We generally breathe faster
when our body needs more energy for example while exercising.
This is so because the body needs more oxygen that can break down the food and
produce more energy.
An average adult human being breeds 15 to 18 times in a minute. While exercising,
this rate can change up to 25 times a minute.
KVS ZIET CHD Class VII-Science 2023-24 Page 34
make wine and beer. This is called as alcohol fermentation.
Anaerobic respiration in human beings
Sometimes muscles of human beings can respire without oxygen.
This generally happens when we undergo a heavy exercise such as running,
weightlifting, cycling or walking for a longer duration.
In such situations, the muscles require more energy and the supply of oxygen is not
enough.
Hence anaerobic respiration takes place in the muscles.
As a result of muscles also produce lactic acid along with energy.
This lactic acid accumulates in the muscles and causes cramps.
That is why we often feel cramps while we do heavy exercises.
In order to get relief from cramps, we can take a hot water bath or massage our
muscles.
This is so because hot water bath or massage improves the blood circulation in the
muscles.
As a result, the oxygen reaches the cells easily which breaks on the lactic acid into
carbon dioxide and water.
Breathing:
Breathing can be defined as a process in which organisms, with the help of their
respiratory organs, take in the oxygen-rich air present in the surroundings and release
out air that contains high amount of carbon dioxide in it. Breathing occurs
continuously in the organisms.
Inhalation is the process of taking the air that contains oxygen inside the body.
Exhalation is a process of releasing out air that contains carbon dioxide out of the
body. Inhalation and exhalation take place alternatively in the breathing process.
Breathing rate can be defined as the number of times a person breathes in a minute.
A breath can be defined as an inhalation followed by an exhalation.
The breathing rate is not always constant in human beings. We generally breathe faster
when our body needs more energy for example while exercising.
This is so because the body needs more oxygen that can break down the food and
produce more energy.
An average adult human being breeds 15 to 18 times in a minute. While exercising,
this rate can change up to 25 times a minute.
KVS ZIET CHD Class VII-Science 2023-24 Page 34
Page 4
Relation between Breathing and Cellular Respiration
Why do we feel hungry after doing a physical activity like walking or running?
When we do a physical activity the food that is present in our body is converted into
energy. Since all the food gets consumed in generating the energy we start feeling
hungry. Hence in order to gain more energy we need to eat more food.
The mechanism of breathing in human beings
The Respiratory System in Humans
We take in the air present in the environment through our nostrils which travels
through the nasal cavity.
Then it moves through the windpipe and reaches the lungs.
The lungs are located in the chest cavity which is surrounded by the ribs.
On the floor of the chest cavity lays a muscle sheet called diaphragm.
During the breathing process, the movement of the ribs an d diaphragm takes place.
This is so because the lungs expand and contract during breathing.
As we take in the air it fills up the lungs. This moves the diaphragm downwards and
the ribs outwards.
The lungs when releasing out air from the body which brings b ack the diaphragm and
the ribs to their original positions.
KVS ZIET CHD Class VII-Science 2023-24 Page 35
Why do we feel hungry after doing a physical activity like walking or running?
When we do a physical activity the food that is present in our body is converted into
energy. Since all the food gets consumed in generating the energy we start feeling
hungry. Hence in order to gain more energy we need to eat more food.
The mechanism of breathing in human beings
The Respiratory System in Humans
We take in the air present in the environment through our nostrils which travels
through the nasal cavity.
Then it moves through the windpipe and reaches the lungs.
The lungs are located in the chest cavity which is surrounded by the ribs.
On the floor of the chest cavity lays a muscle sheet called diaphragm.
During the breathing process, the movement of the ribs an d diaphragm takes place.
This is so because the lungs expand and contract during breathing.
As we take in the air it fills up the lungs. This moves the diaphragm downwards and
the ribs outwards.
The lungs when releasing out air from the body which brings b ack the diaphragm and
the ribs to their original positions.
KVS ZIET CHD Class VII-Science 2023-24 Page 35
Page 5
Breathing
Why do we sneeze?
As we inhale the air present in the surroundings sometimes various unwanted elements
such as smoke and dust are also included in it.
However, they get stuck in the hair in our nostrils but some of them can get through
the nasal cavity.
They thus cause irritation in the nasal cavity which makes us sneeze.
This helps in getting rid of the unwanted particles out of the nasal cavity.
Breathing in other organisms
Many animals have just cavities in their bodies just like human beings for example
lions, elephants, goats, cows, snakes and birds.
Breathing in cockroach:
Many insects like Cockroaches have small openings called spiracles present on the
sides of the bodies.
Also, they have an air tube-like structure called the trachea that allows the
exchange of gases in these insects.
The air enters the body through the spiracles and diffuses in the cells via the
trachea.
Similarly, the air from the cells enters the trachea and moves out of the body
through spiracles.
Breathing in earthworms:
Earthworms have a soft, slimming and moist skin.
Hence the gases can easily pass in and out of the earthworm through its skin.
Similarly, frogs also have a slippery and moist skin that can h elp in breathing.
However, frogs contain lungs too.
Breathing underwater
Animals that live underwater have special respiratory organs called gills.
They are a comb-like structure present on the skin of these animals.
KVS ZIET CHD Class VII-Science 2023-24 Page 36
Why do we sneeze?
As we inhale the air present in the surroundings sometimes various unwanted elements
such as smoke and dust are also included in it.
However, they get stuck in the hair in our nostrils but some of them can get through
the nasal cavity.
They thus cause irritation in the nasal cavity which makes us sneeze.
This helps in getting rid of the unwanted particles out of the nasal cavity.
Breathing in other organisms
Many animals have just cavities in their bodies just like human beings for example
lions, elephants, goats, cows, snakes and birds.
Breathing in cockroach:
Many insects like Cockroaches have small openings called spiracles present on the
sides of the bodies.
Also, they have an air tube-like structure called the trachea that allows the
exchange of gases in these insects.
The air enters the body through the spiracles and diffuses in the cells via the
trachea.
Similarly, the air from the cells enters the trachea and moves out of the body
through spiracles.
Breathing in earthworms:
Earthworms have a soft, slimming and moist skin.
Hence the gases can easily pass in and out of the earthworm through its skin.
Similarly, frogs also have a slippery and moist skin that can h elp in breathing.
However, frogs contain lungs too.
Breathing underwater
Animals that live underwater have special respiratory organs called gills.
They are a comb-like structure present on the skin of these animals.
KVS ZIET CHD Class VII-Science 2023-24 Page 36
Page 6
Gills allow the exchange of gases between animals and the water easily.
Some animals called the amphibians can breathe on land by lungs and through
moist skin under water. For example frogs and toads.
Respiration through Gills in Fishes
Respiration in plants-
Respiration in plants
1. We know that plants also respire. They take in the carbon dioxide present in the
atmosphere and use it in the process of photosynthesis to produce food. As a result of
photosynthesis in plants, they release out oxygen in the environment.
2. All the parts of the plants can independently respire that is they can take in the carbon
dioxide and release oxygen on their own.
3. The leaves of the plants have stomata present upon them which are small pore -like
structures. The allow gases exchange in leaves.
4. The woody stems of the plants also respire. This is because of the presence of special
tissue called Lenticels. The cells of this tissue have large intercellular spaces. They exist
as dead cells on woody plants and roots and allow the exchange of gases. The bark of
trees although is impermeable to gases hence these tissues serve an important purpose of
respiration in the stems. As the name suggests, lenticels have a lens-like shape.
KVS ZIET CHD Class VII-Science 2023-24 Page 37
Some animals called the amphibians can breathe on land by lungs and through
moist skin under water. For example frogs and toads.
Respiration through Gills in Fishes
Respiration in plants-
Respiration in plants
1. We know that plants also respire. They take in the carbon dioxide present in the
atmosphere and use it in the process of photosynthesis to produce food. As a result of
photosynthesis in plants, they release out oxygen in the environment.
2. All the parts of the plants can independently respire that is they can take in the carbon
dioxide and release oxygen on their own.
3. The leaves of the plants have stomata present upon them which are small pore -like
structures. The allow gases exchange in leaves.
4. The woody stems of the plants also respire. This is because of the presence of special
tissue called Lenticels. The cells of this tissue have large intercellular spaces. They exist
as dead cells on woody plants and roots and allow the exchange of gases. The bark of
trees although is impermeable to gases hence these tissues serve an important purpose of
respiration in the stems. As the name suggests, lenticels have a lens-like shape.
KVS ZIET CHD Class VII-Science 2023-24 Page 37
Page 7
Lenticels in plants
5. The roots of the plants have hair-like structures on them. Hence they can absorb the air
present in the soil.
Respiration in Leaves through Stomata
Why plants can die if overwatered?
We know that the roots get oxygen from the soil.
We also understand that the air in the soil is present between the soil particles.
Along with the air, soil also contains some water or moisture.
If we over-water the plants the spaces between the soil particles get clogged.
As a result, the roots will not be able to get enough air and the plant can die.
Roots can absorb air from the soil
SOME IMPORTANT QUESTIONS
1. Where does cellular respiration take place?
Answer: Cellular respiration takes place in the cells of all organisms.
2. What is aerobic respiration?
Answer: The process of breakdown of glucose with the use of oxygen is called aerobic
respiration.
3. What are some common uses of Yeast?
Answer: Some common uses of Yeast are bread, wine and beer.
4. Name an organism that can survive in the absence of air.
Answer: Yeast can survive in the absence of air.
5. How do earthworms breathe?
Answer: Earthworms breathe through their skins.
6. What does a breath mean?
KVS ZIET CHD Class VII-Science 2023-24 Page 38
5. The roots of the plants have hair-like structures on them. Hence they can absorb the air
present in the soil.
Respiration in Leaves through Stomata
Why plants can die if overwatered?
We know that the roots get oxygen from the soil.
We also understand that the air in the soil is present between the soil particles.
Along with the air, soil also contains some water or moisture.
If we over-water the plants the spaces between the soil particles get clogged.
As a result, the roots will not be able to get enough air and the plant can die.
Roots can absorb air from the soil
SOME IMPORTANT QUESTIONS
1. Where does cellular respiration take place?
Answer: Cellular respiration takes place in the cells of all organisms.
2. What is aerobic respiration?
Answer: The process of breakdown of glucose with the use of oxygen is called aerobic
respiration.
3. What are some common uses of Yeast?
Answer: Some common uses of Yeast are bread, wine and beer.
4. Name an organism that can survive in the absence of air.
Answer: Yeast can survive in the absence of air.
5. How do earthworms breathe?
Answer: Earthworms breathe through their skins.
6. What does a breath mean?
KVS ZIET CHD Class VII-Science 2023-24 Page 38
Page 8
Answer: A breath means one inhalation plus one exhalation.
7. What is cell?
Answer: A cell is the smallest structural and functional unit of an organism.
8. What are all organisms made up of?
Answer: All organisms are made of small microscopic units called cells.
9. Name the respiratory organ of birds.
Answer: They have lungs in their chest cavities like the human beings.
10. What forms the floor of the chest cavity?
Answer: A large, muscular sheet called diaphragm forms the floor of the chest cavity.
11. What are the end products of anaerobic respiration?
Answer: The end products of anaerobic respiration are alcohol, carbon dioxide and energy.
12. What is produced during anaerobic respiration in muscles that causes cramps?
Answer: Lactic acid is produced during anaerobic respiration in muscles that causes cramps.
13. What is cellular respiration?
Answer: The process of breakdown of food in the cell with the release of energy is called
cellular respiration.
14. What is breathing rate?
Answer: The number of times a person breathes in a minute is termed as the breathing rate.
15. Why smoking should be avoided?
Answer: Smoking damages lungs. Smoking is also linked to cancer. So, it must be avoided.
16. What are spiracles?
Answer: Insects have small openings on their body that allow them to breathe. These openings
are called spiracles.
17. Why we should eat regularly?
Answer: We should eat regularly because food has stored energy, which is released during
respiration.
18. What is a stomata and what is its function?
Answer: Leaves of the plants have tiny pores called stomata for exchange of oxygen and carbon
dioxide.
19. What is breathing?
Answer: Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide
with the help of respiratory organs.
20. What is inhalation and exhalation?
Answer: The taking in of air rich in oxygen into the body is called inhalation and giving out of
air rich in carbon dioxide is known as exhalation.
Short Extra Questions and Answers-
1. How do frogs breathe?
Answer: Frogs have a pair of lungs like human beings to breathe air. They can also breathe
through their skin, which is moist and slippery.
2. Name some animals that breathe through lungs.
Answer: Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, birds, have lungs
in their chest cavities like the human beings.
3. Why do mountaineers carry oxygen with them?
Answer: Mountaineers carry oxygen with them because the amount of air available to a person
is less than that available on the ground.
KVS ZIET CHD Class VII-Science 2023-24 Page 39
7. What is cell?
Answer: A cell is the smallest structural and functional unit of an organism.
8. What are all organisms made up of?
Answer: All organisms are made of small microscopic units called cells.
9. Name the respiratory organ of birds.
Answer: They have lungs in their chest cavities like the human beings.
10. What forms the floor of the chest cavity?
Answer: A large, muscular sheet called diaphragm forms the floor of the chest cavity.
11. What are the end products of anaerobic respiration?
Answer: The end products of anaerobic respiration are alcohol, carbon dioxide and energy.
12. What is produced during anaerobic respiration in muscles that causes cramps?
Answer: Lactic acid is produced during anaerobic respiration in muscles that causes cramps.
13. What is cellular respiration?
Answer: The process of breakdown of food in the cell with the release of energy is called
cellular respiration.
14. What is breathing rate?
Answer: The number of times a person breathes in a minute is termed as the breathing rate.
15. Why smoking should be avoided?
Answer: Smoking damages lungs. Smoking is also linked to cancer. So, it must be avoided.
16. What are spiracles?
Answer: Insects have small openings on their body that allow them to breathe. These openings
are called spiracles.
17. Why we should eat regularly?
Answer: We should eat regularly because food has stored energy, which is released during
respiration.
18. What is a stomata and what is its function?
Answer: Leaves of the plants have tiny pores called stomata for exchange of oxygen and carbon
dioxide.
19. What is breathing?
Answer: Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide
with the help of respiratory organs.
20. What is inhalation and exhalation?
Answer: The taking in of air rich in oxygen into the body is called inhalation and giving out of
air rich in carbon dioxide is known as exhalation.
Short Extra Questions and Answers-
1. How do frogs breathe?
Answer: Frogs have a pair of lungs like human beings to breathe air. They can also breathe
through their skin, which is moist and slippery.
2. Name some animals that breathe through lungs.
Answer: Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, birds, have lungs
in their chest cavities like the human beings.
3. Why do mountaineers carry oxygen with them?
Answer: Mountaineers carry oxygen with them because the amount of air available to a person
is less than that available on the ground.
KVS ZIET CHD Class VII-Science 2023-24 Page 39
Page 9
4. Why should we cover our nose while sneezing?
Answer: When we sneeze, we should cover our nose so that the foreign particles we expel are
not inhaled by other persons.
5. How does respiration occur in earthworms?
Answer: Earthworms breathe through their skins. The skin of an earthworm feels moist and
slimy on touching. Gases can easily pass through them.
6. What role does hair present in the nasal cavity play in the process of respiration?
Answer: When we inhale, the particles get trapped in the hair present in our nasal cavity. Thus,
the hairs present in the nasal cavity filters the air.
7. What is normal range of breathing rate per minute in an average adult person at rest?
Answer: On an average, an adult human being at rest breathes in and out 15ñ18 times in a
minute.
8. Why do we get muscle cramps after heavy exercise?
Answer: The cramps occur when muscle cells respire anaerobically. The partial breakdown of
glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.
9. What happens during exhalation?
Answer: During exhalation, ribs move down and inwards, while diaphragm moves up to its
former position. This reduces the size of the chest cavity and air is pushed out of the lungs.
10. What happens during inhalation?
Answer: During inhalation, ribs move up and outwards and diaphragm moves down. This
movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled
with air.
11. What happens to the air we breathe in?
Answer: The air we breathe in is transported to all parts of the body and ultimately to each cell.
In the cells, oxygen in the air helps in the breakdown of food and energy is released.
12. How does respiration work in yeast?
Answer: Yeasts are single-celled organisms. They get energy through anaerobic respiration. In
the absence of oxygen, glucose breaks down into alcohol and carbon dioxide.
13. Why are yeasts used to make wine and beer?
Answer: Yeasts are single-celled organisms. They respire anaerobically and during this process
yield alcohol. They are, therefore, used to make wine and beer.
14. What is the function of gills in fish?
Answer: Gills in fish help them to use oxygen dissolved in water. Gills are projections of the
skin and are well supplied with blood vessels for exchange of gases.
15. How do plant roots respire?
Answer: Like all other living cells of the plants, the root cells also need oxygen to generate
energy. Roots take up air from the air spaces present between the soils particles.
KVS ZIET CHD Class VII-Science 2023-24 Page 40
Answer: When we sneeze, we should cover our nose so that the foreign particles we expel are
not inhaled by other persons.
5. How does respiration occur in earthworms?
Answer: Earthworms breathe through their skins. The skin of an earthworm feels moist and
slimy on touching. Gases can easily pass through them.
6. What role does hair present in the nasal cavity play in the process of respiration?
Answer: When we inhale, the particles get trapped in the hair present in our nasal cavity. Thus,
the hairs present in the nasal cavity filters the air.
7. What is normal range of breathing rate per minute in an average adult person at rest?
Answer: On an average, an adult human being at rest breathes in and out 15ñ18 times in a
minute.
8. Why do we get muscle cramps after heavy exercise?
Answer: The cramps occur when muscle cells respire anaerobically. The partial breakdown of
glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.
9. What happens during exhalation?
Answer: During exhalation, ribs move down and inwards, while diaphragm moves up to its
former position. This reduces the size of the chest cavity and air is pushed out of the lungs.
10. What happens during inhalation?
Answer: During inhalation, ribs move up and outwards and diaphragm moves down. This
movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled
with air.
11. What happens to the air we breathe in?
Answer: The air we breathe in is transported to all parts of the body and ultimately to each cell.
In the cells, oxygen in the air helps in the breakdown of food and energy is released.
12. How does respiration work in yeast?
Answer: Yeasts are single-celled organisms. They get energy through anaerobic respiration. In
the absence of oxygen, glucose breaks down into alcohol and carbon dioxide.
13. Why are yeasts used to make wine and beer?
Answer: Yeasts are single-celled organisms. They respire anaerobically and during this process
yield alcohol. They are, therefore, used to make wine and beer.
14. What is the function of gills in fish?
Answer: Gills in fish help them to use oxygen dissolved in water. Gills are projections of the
skin and are well supplied with blood vessels for exchange of gases.
15. How do plant roots respire?
Answer: Like all other living cells of the plants, the root cells also need oxygen to generate
energy. Roots take up air from the air spaces present between the soils particles.
KVS ZIET CHD Class VII-Science 2023-24 Page 40
Page 10
Study Materials
Notes
Model Papers Class 6 Notes
Sample Papers Class 7 Notes
Half Yearly Sample Papers Class 8 Notes
Class 9 Notes
Important Resources
Class 10 Notes
Periodic Table
Class 11 Notes
Writing Skills / Formats
Maps of India / World Class 12 Notes
Books and Solutions
NCERT Books
NCERT Book Solutions
HC Verma Chapter Wise Solutions
RD Sharma Solutions
CGBSE Solutions
Notes
Model Papers Class 6 Notes
Sample Papers Class 7 Notes
Half Yearly Sample Papers Class 8 Notes
Class 9 Notes
Important Resources
Class 10 Notes
Periodic Table
Class 11 Notes
Writing Skills / Formats
Maps of India / World Class 12 Notes
Books and Solutions
NCERT Books
NCERT Book Solutions
HC Verma Chapter Wise Solutions
RD Sharma Solutions
CGBSE Solutions
Document Details
| Board / Org | Aglasem |
| Exam | Class 7 |
| Type | Notes |
| Pages | 8 |
| Language | english |
| Updated | 30 Apr 2026 |