Lesson: Respiration in Organisms

Question: 1

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

Solution:

When an athlete is running, his muscle cells are hard at work and needs more energy, for which the athlete starts breathing faster. As he breathes deeper and faster, more oxygen goes to the cells and it helps in the faster breakdown of food which in turn releases more energy.

Question: 2

List the similarities and differences between aerobic and anaerobic respiration.

Solution:

Similarity: In both cases, the food is oxidised to release energy.

Differences:

Question: 3

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

Solution:

Sneezing is a way to remove the unwanted foreign particles from the nostrils. It occurs when there is an irritation in the form of pollens, dust, smoke, etc., in the upper part of the respiratory tract.

Question: 4

Take three test-tubes. Fill 3/4th 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?

Solution:

The living organisms produce CO2 during respiration which is used by plants during photosynthesis. Therefore, the test tube A containing the snail will have the highest concentration of carbon dioxide, produced during respiration by the snail. In test tube B the plant performs photosynthesis, which uses carbon dioxide; hence it will have more oxygen: while in test tube C the carbon dioxide produced by the snail is utilized by the plant for photosynthesis, therefore keeping the concentration of carbon dioxide low in it.

Question: 5

(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)                 9-12

(ii)              15-18

(iii)            21-24

(iv)             30-33

(d)               During exhalation, the ribs

(i)                 move outwards

(ii)              move downwards

(iii)            move upwards

(iv)             do not move at all

Solution:

(a)   (iii) spiracles

(b)   (ii) lactic acid

(c)   (ii) 15-18

(d)   (ii) move downwards

Question: 6

Match the items in Column I with those in Column II:

Solution:

Question: 7

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)

Solution:

(i)                 False

(ii)              False

(iii)            True

(iv)             False

(v)               True

Question: 8

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

(vii)    The openings through which we inhale

(viii)  An anaerobic organism

(ix)       An organism with tracheal system

Solution:

(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 of leaf $–$ Stomata

(v)         Small openings on the sides of the body of an insect $–$ Spiracles

(vi)       The respiratory organs of human beings $–$ Lungs

(vii)    The openings through which we inhale $–$ Nostrils

(viii)  An anaerobic organism $–$ Yeast

(ix)       An organism with tracheal system $–$ Ant

Question: 9

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.

Solution:

(b) The amount of air available to a person is less than that available on the ground.