Chapter 7 | Respiration in Organisms | Class-7 DAV Science Solutions

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DAV Class-8 Respiration in Organisms Question and Answer

Something To Know

A. Fill in the blanks.

1. Lactic acid is produced during ___________ respiration.

2. Insects have organs, called ___________, for respiration.

3. Taking in of air, rich in oxygen, is called ___________.

4. An adult human being normally breathes from ___________ to ___________ times per minute.

5. The movement of lungs is controlled by the ___________ and the ___________.

6. ___________ acts as the respiratory carrier in our body.

Answer: (1) anaerobic (2) tracheae (3) inhalation (4) 14, 20 (5) diaphragm, ribcage (6) Haemoglobin

B. Match the following:

1. Lactic acid ————-> (c) Muscle cramps

2. Stomata  ————–> (a) Transpiration

3. Respiratory carrier ——> (e) Haemoglobin

4. Lenticels ————-> (b) Pores on branches

5. Alcohol ————–> (d) Fermentation of yeast

Answer: 1. (c), 2. (a), 3. (e), 4. (b), 5. (d)

C. Tick the correct option.

1. Respiration helps in—

Ans 1. obtaining energy

2. Stomata perform the function of—

Ans 2. exchange of gases

3. The process represented by the following equation, (glucose + oxygen carbon dioxide + water + energy)

Ans 3. is aerobic respiration

4. To survive, plant roots need—

Ans 4. oxygen

5. Earthworms and leeches respire through their—

Ans 5. skin

D. Answer the following questions in brief.

Q. 1. Define respiration. Name the two types of respiration.

Ans 1: The process in which living organisms convert sugars into biological energy using oxygen is called respiration. 

Two types of respiration are –

(1) Aerobic respiration

(2) Anaerobic respiration

Q. 2. Name the respiratory organ of the following:

(a) crab (b) man (c) leech (d) an insect

Ans 2: (a) Gills

(b) Lungs

(c) Skin

(d) Tracheae

Q. 3. Define transpiration.

Ans 3: Loss of excess water from plants through open stomata is called transpiration

Q. 4. Define the term ‘breathing rate’.

Ans 4: The number of times an animal breathes per minute is called its breathing rate.

Q. 5. Name the body organs which help the lungs during the process of breathing.

Ans 5: Ribcage and diaphragm.

Q. 6. Why do we need to breathe out carbon dioxide?

Ans 6: High levels of carbon dioxide in the body can be toxic and hence, carbon dioxide needs to be removed.

E. Answer the following questions.

Q. 1. Why do we get muscle cramps after heavy exercise?

Ans 1. During heavy exercise, we need more energy but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes place is the muscles cells to fulfil the demand of energy. This leads to the formation of lactic acid which accumulates in muscles. Because of this, the muscles cannot continue working for long. They get fatigued after sometime causing muscle cramps.

Q. 2. Why does a potted plant die when overwatered?

Ans 2: A potted plant dies when overwatered because the cells, in the roots of the plants, also need oxygen to survive. They take in air from the air spaces present between the soil particles. When overwatered, the air spaces, in the soil, get occupied by water and thus prevent the plant’s roots from taking in air that they need. Therefore, a potted plant dies if over-watered.

Q. 3. Where are stomata found in a plant? State their function.

Ans 3: Stomata are found on the surface of the leaves of a plant.

Functions of stomata – 

(1) Help in the exchange of gases (oxygen and carbon dioxide). 

(2) Lose excess amount of water in the form of water vapour.

Q. 4. How is oxygen transported from lungs to the other parts of the body?

Ans 4: Oxygen is transported from the lungs to the other parts of the body with the help of haemoglobin. The blood, while passing through the lungs, picks up oxygen with the help of haemoglobin which transports oxygen to different parts of the body.

Q. 5. Draw a neat, well-labelled diagram of the human respiratory system.

Ans 5: 

Chapter 7 | Respiration in Organisms | Class-7 DAV Science Solutions

Q. 6. Describe an activity to show that exhaled air contains carbon dioxide.

Ans 6. Take a drinking straw and a test tube containing freshly prepared lime water. Place one end of the straw in the lime water and blow the exhaled air gently at the other end of the straw. Lime water turns milky which shows the presence of carbon dioxide in the exhaled air.

Q. 7. Describe the changes that take place (i) around the rib cage (ii) diaphragm (iii) chest cavity, during inspiration. State the effect of these changes.

Ans 7: (1) During inspiration, the muscles, around the rib cage, contract, lifting the ribs upward and outward 

(2) Diaphragm contracts and becomes nearly flat sheet. 

(3) The chest cavity expands.

Effect – Air pressure inside the lungs falls below the pressure of the air outside the body. This creates a partial vacuum and so the air from outside the body rushes into the lungs.

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