Explore NCERT Solutions

Chapter Review:

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• The process of breakdown of food in the cell with the release of energy is called cellular respiration. 

• The process of breakdown of food in the cell with the release of energy is called cellular respiration. 

• Food can also be broken down , without using oxygen.This is called anaerobic respiration.

• Some organisms such as yeast that can survive in the absence of air. they are called anaerobes.

• Yeasts are used to make wine and beer.

• The taking in of air rich in oxygen into the body is called inhalation

• Giving out of air rich in carbon dioxide is known as exhalation. .

• The number of times a person breathes in a minute is termed as the
  breathing rate.

• An adult human being at rest breathes in and out 15–18 times in a minute.

• Insects have a network of air tubes called tracheae.

• Increased physical activity enhances the rate of breathing.

Exercise 

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Q1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Answer:

During running, the athlete uses up lot of energy. So, he/she needs more energy and so breathes faster breakdown of food to release energy.

Q2. List the similarities and differences between aerobic and anaerobic respiration.

Answer:

Similarity: (i) Energy is released.

(ii)Carbon dioxide is produced.

Differences: (i) Anaerbic respiration does not reqire oxygen while aerobic respiration take place in the presence of oxygen.

(ii) Glucose is completly broken down into carbon dioxide and water in aerobic respiration but not in anaerobic respiraton.

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

Answer:

When we inhale a lot of dust laden air often these particles get trapped in the hair present in the nasal cavity. then they irritate the lining of the cavity,as a result  of which we sneeze. Sneezing expels these foregion particles from the inhaled air and a dust free, clean air enters our body. 

4. Take three test-tubes.Fill th 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?

Answer: 

Test - Tube - C.

5. 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 accu mulation 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) 9–12 (ii) 15–18 (iii) 21–24 (iv) 30–33

Answer:

(a) - (iii)

(b) - (ii)

(c) -(ii) 

(d) - (ii)

Column I Column II6. Match the items in Column I with those in 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 

Answer: 

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

Q7. Mark ‘T’ if the statement is true and ‘F’ 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)

air is higher than that on the ground. (T/F)

Answer:

(i) false

(ii) false

(iii) true

(iv) false

(v) true

Additional Questions With Solutions

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Ques: What is cellular respiration?
Ans: The process of breakdown of food in the cell with the release of energy is called cellular respiration.

Ques: Where does cellular respiration take place?
Ans: It take place in the cells of organisms.

Ques: Write the name of respiratory organs of earthworm.
Ans:  Skin.`
Ques: Write the differences between aerobic respiration and anaerobic respiration.
Ans:

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Ques: What is aerobic respiration ?
Ans: Breakdown of glucose occurs with the use of oxygen.
It is called aerobic respiration.

Ques: What is anaerobic respiration?
Ans: food can also be broken down, without using oxygen. This is called anaerobic respiration.

Ques: What are anaerobes?
Ans: Some organisms such as yeast that can survive in the
Absence of air. they are called anaerobes.

Ques: Why do you get muscle cramps after heavy exercise?
Ans: There begins to lack of oxygen during heavy exercise and muscle cells respire anaerobically by which glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.

Ques: Why do we get relief from cramps after a hot water bath or a massage.
Ans: The blood circulation increases after a hot water bath or a massage. As a result, the supply of oxygen to the muscle cells increases by which there takes place the complete breakdown of lactic acid into carbon dioxide and water.

Ques: What are spiracles?
Ans: Other insects also have similar opening. These opening are called spiracles.

Ques: What are tracheae?
Ans: Insects have a network of air tubes called tracheae.

Ques: What is inhalation?
Ans: The taking in air rich in oxygen into the body is called
Inhalation.

Ques: What is exhalation?
Ans: Giving out of air rich in carbon dioxide is known as exhalation.

Ques: What is breathing rate?
Ans: The time of time a person breathes in a minute is termed As the breathing rate.

Ques: What is breathing rate in an adult?
Ans: 15-18 times.

Ques: Why do we yawn?
Ans: When reduce our respiratory rate we do not get enough oxygen hence yawns comes again and again for completing the oxygen demand and we take deep breaths.  

Extra Question:

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Que: What are the end probucts of aerobic respiration.

Ans: During aerobic respiration, carbon dioxide and water are eleased along with a large amount of energy.

Que: The cellular respiration process takes place in which cell organelle?

Ans: Cellular respiration takes place in the mitochondria of the cell.

Que: in some animals, exchange of gases takes place through its thin and moist skin. Name one such animal?

Ans:  Earthworm is an animal where exchange of gases during breathing or respiration takes place tjrough lits thin and moist skin.

Que:Give the name of respiratoyr organs in following animals.

(a) Fish

(b) Human being

Ans: 

(a) Fish - Gills

(b) human being - lungs

Que: Our nostrills has hair and mucous. What is the need to have them in our nasal cavity?

Ans: Our nostrills possess hairs and mucous lining. These help in preventing dirt, dust and germs from entering our respiratory system.

Que:Sometime we seen that farmers loosen the soil. What is the reason behind it?

Ans: The farmers sometimes loosen the soil. This helps the root to through the air present in the space between soil particles.

Que:Various organs constitute the respiratory system of human. These organs are locted according to their functions. Identify them.

Ans: The various organs in the respiratory system of human are nostrills, nasal passage, nasal cavity, windpipe and lungs.