Respiration in Organisms Question Answers: NCERT Class 7 Science

Welcome to the Chapter 10 - Respiration in Organisms, Class 7 Science - NCERT Solutions page. Here, we provide detailed question answers for Chapter 10 - Respiration in Organisms.The page is designed to help students gain a thorough understanding of the concepts related to natural resources, their classification, and sustainable development.

Our solutions explain each answer in a simple and comprehensive way, making it easier for students to grasp key topics and excel in their exams. By going through these Respiration in Organisms question answers, you can strengthen your foundation and improve your performance in Class 7 Science. Whether you're revising or preparing for tests, this chapter-wise guide will serve as an invaluable resource.

The process of inhaling of oxygen and exhaling of carbon- dioxide is called as breathing.
The process of breakdown of food in cells is known as cellular respiration.
The organisms who does not need oxygen for respiration are known as anaerobes.
Respiration is of two types- aerobic respiration and anaerobic respiration.
The respiration which need oxygen or which occur in the presence of oxygen is called aerobic respiration.
The respiration which occur in the absence of oxygen is called anaerobic respiration.
Muscles respire anaerobically this respiration process occur due to the lack of oxygen.
Breathing rate is defined as the number of breathes in one minute.
Diaphragm is the muscular sheet which forms a floor for the chest cavity and it protects the delicate organs like heart.
Process of respiration is -air from environment- nasal cavity- lungs.
Rib cage is a structure of bones in which is connected to backbone.
As we inhale air inside, size of diaphragm increases.
On exhalation, size of diaphragm decreases.
In human body a pair of lungs is present which purify air.
For the exchange of gases insects chewing a network of air tubes called trachea.
Exchange of gases takes place through skin in earthworm.
Unlike humans, fishes have gills with higher blood supply for breathing.
Exchange of gases takes place through stomata which are present on the surface of leaves in plants.

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Exercise 1 ( Page No. : 118 )

Why does an athlete breathe faster and deeper than usual after finishing the race?

Ans:

An athlete breathe faster and deeper than usual after finishing the race because he needs extra energy to his muscles which worked hard during running. For this reason, he breathes faster and deeper so that he can supply more oxygen to the cells. During running, the oxygen level of the athlete becomes less. To complete the oxygen level, he breathes faster than usual. He respires anaerobically at that time.

List the similarities and differences between aerobic and anaerobic respiration.

Ans:

Similarities between Aerobic and Anaerobic Respiration

Aerobic respiration	Anaerobic respiration
1. In aerobic respiration, energy is produced by the breakdown of food (like glucose).	1. In anaerobic respiration also energy is produced by the breakdown of food (like glucose).
2. Aerobic respiration takes place in the cells of the organism.	2. Anaerobic respiration also takes place in the cells of the organism.

Differences between Aerobic and Anaerobic Respiration

Aerobic respiration	Anaerobic respiration
1. Aerobic respiration takes place in the presence of oxygen.	1. Anaerobic respiration takes place in the absence of oxygen.
2. Complete breakdown of food occurs in aerobic respiration.	2. Partial breakdown of food occurs.
3. The end products in aerobic respiration are carbon dioxide and water.	3. The end products in anaerobic respiration may be alcohol and carbon dioxide like in yeast, or lactic acid like in muscles.
4. Aerobic respiration produces a considerable amount of energy.	4. Much less energy is produced in anaerobic respiration.
5. Fermentation process is shown by the anaerobes in the cytoplasm. In this Glucose breaks down into ethyl alcohol and carbon dioxide without using oxygen, also known as alcoholic fermentation and lactic acid fermentation. Alcoholic fermentation or yeast oxidization:- C₆H₁₂O₆ → 2 C₂H₅OH + 2 CO₂ + Energy (Glucose) (Ethyl alcohol) (Carbon dioxide)	5. Glucose get break down into the carbon dioxide, water and energy is released in the form of ATP is aerobic respiration. It yields more energy available in glucose. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (Glucose) (Oxygen) (Carbon dioxide) (Water) (Stored in ATP)

Why do we often sneeze when we inhale a lot of dust-laden air?

Ans:

We often sneeze when we inhale lot of dust- laden air because it expells out the foreign particles from the air that is trapped inside the nose. Sneeze happens when we inhale dust particles or contaminants present in air, they get trapped in to the hair of nose and get accumulated there. then which may can cause sneeze.

Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO₂?

Ans:

test tubes

Three test-tubes are taken and labelled A, B and C. Each test- tube is half filled with water.
(a) In test-tube A, a snail is kept,
(b) In test-tube B, a water plant is kept, and
(c) In test-tube C contains both a snail and a water plant.

(a) Test-tube A contains a snail in water. The snail will use up oxygen for respiration and produce carbon dioxide.
(b) Test-tube B contains a ‘water plant’ in water. The water plant will do photosynthesis by using carbon dioxide and water and produce oxygen. The water plant will use some of this oxygen for respiration and produce carbon dioxide will then be used by the plant in photosynthesis.
(c) Test-tube C contains both, a snail and a water plant. The carbon dioxide produced by the snail through the respiration is used by the plant for the synthesis of food and oxygen is released by the plant which is used by the snail for the respiration.

From the above, we conclude that the test-tube A containing only snail will have the highest concentration of carbon dioxide because there is no plant to use up the carbon dioxide produced during the respiration in snail.

Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs (ii) gills
(iii) spiracles (iv) skin

(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide (ii) lactic acid
(iii) alcohol (iv) water

(c) Normal range of breathing rate per minute in an average adult person at rest is:
(i) 9ñ12 (ii) 15ñ18
(iii) 21ñ24 (iv) 30ñ33

(d) During exhalation, the ribs
(i) move outwards (ii) move downwards
(iii) move upwards (iv) do not move at all

Ans:

(a) (iii) Spiracles
On the body of cockroach tiny holes are prsent on sides, these are called spiracles. Exchange of gases takes place through spiracles.

(b) (ii) Lactic acid
During heavy exercise we get cramps in the legs due to the accumulation of lactic acid because that time our muscles starts respire anaerobically. During anaerobic respiration, partial breakdown of glucose occur which forms lactic acid. When lactic acid accumulates in the muscles, causes muscle cramps.

(c) (ii) 15-18
The normal range of breathing rate per minute in a person at rest is 15- 18. Breathing rate can be determined by the number of breathes in per minute.

(d) (ii) Moves downward
During exhalation, air comes out. In exhalation process, our ribs moves in downward and inward direction whereas diaphragm expands in size.

Match the items in Column I with those in Column II:
Column I Column II
(a) Yeast (i) Earthworm
(b) Diaphragm (ii) Gills
(c) Skin (iii) Alcohol
(d) Leaves (iv) Chest cavity
(e) Fish (v) Stomata
(f) Frog (vi) Lungs and skin
(vii) Tracheae

Ans:

Column I Column II
(a) Yeast (iii) Alcohol
(b) Diaphragm (iv) Chest cavity
(c) Skin (i) Earthworm
(d) Leaves (v) Stomata
(e) Fish (ii) Gills
(f) Frog (vi) Lungs and skin

1. Yeast: Yeast is a single- celled organism which respries anaerobically. Yeast is used to produce alcohol by fermentation process by converting glucose into alcohol.

2. Diaphragm: The diaphragm is made up of rib cage. It is present in chest cavity. It expands inside when we inhale and during exhalation it contracts.

3. Earthworm: The earthworm respires through skin. The skin of earthworm is slipery and soft. Exchange of gases takes place through the skin.

4. Leaves: Tiny pores present on the surface of the leaves called stomata. Stomata are the beans shaped structure which is protected by the two guard cells and helps in the exchange of gases. Transpiration of water also occurs through stomata.

5. Fish: Fish respires through gills. The breathing rate of fish is faster than the terrestrial organisms because they use dissolved oxygen in the water which is less in quantity as compared to the environment.

6. Frog: Frogs respire through lungs as well as skin. Because frog acquires terrestrial as well as aquatic habitat.

Exercise 11 ( Page No. : 119 )

Q7	Mark ëTí if the statement is true and ëFí if it is false: (i) During heavy exercise the breathing rate of a person slows down. (T/F) (ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F) (iii) Frogs breathe through their skins as well as their lungs. (T/F) (iv) The fishes have lungs for respiration. (T/F) (v) The size of the chest cavity increases during inhalation. (T/F)
Ans:	(i) False During heavy excersize the breathing rate of a person is faster than as usual because of the lack of oxygen in the cells. To complete the oxygen level he breathes faster and deeper. (ii) False This statement is false because the process of photosynthesis is done only in the day time whereas they respire all the time. (iii) True This statement is true because frog acquires both terrestrial and aquatic habitat. (iv) False This statement is false because they have gills which helps them to use dissolved oxygen. (v) True Lungs can be expanded by the downward and upward movement of diaphragm by intake of fresh air to expand the chest cavity.

Q8	Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction ó upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square. (i) The air tubes of insects (ii) Skeletal structures surrounding chest cavity (iii) Muscular floor of chest cavity (iv) Tiny pores on the surface of leaf (v) Small openings on the sides of the body of an insect (vi) The respiratory organs of human beings (vii) The openings through which we inhale (viii) An anaerobic organism (ix) An organism with tracheal system
Ans:	(i) The air tubes of insects - Trachea (ii) Skeletal structures surrounding chest cavity - Ribs (iii) Muscular floor of chest cavity - Diaphragm (iv) Tiny pores on the surface on leaf - Stomata (v) Small openings on the sides of the body of an cockroach - Spiracles (vi) The respiratory organs of human being - Lungs (vii) The opening through which we inhale - Nostrils (viii) An anaerobic organism - Yeast (ix) An organism with tracheal system - Ant.

Q9	The mountaineers carry oxygen with them because: (a) At an altitude of more than 5 km there is no air. (b) The amount of air available to a person is less than that available on the ground. (c) The temperature of air is higher than that on the ground. (d) The pressure of air is higher than that on the ground.
Ans:	(b) The amount of air available to a person is less than that available on the ground. The mountaineers carry oxygen cylinders with them because as they go higher the amount of oxygen level decreases in the air. They carry oxygen because the amount of air available to a person is less than that available on the ground.