Question 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 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

Answer

(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.

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