Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain.
Draw a diagram of human respiratory system and label-pharynx, trachea, lungs, diaphragm and alveolar sac on it.
CBSE 31-1-2 PAPER SET 2020
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Aquatic organisms breathe faster as compared to terrestrial organisms. This is because the amount of $O _2$ present in the water is very less as compared to the amount of $O _2$ present in the air. That's why aquatic organisms to get more $O _2$, they need to breath faster as compared to terrestrial organisms.
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If a person holds his breath after expiration for about 25sec, would there be occurrence of any exchange of respiratory gases in the lungs during this period? Explain.
When a person puts food in his mouth, then teeth cut it into small pieces, chew and grind it. The glands A in the mouth secrete a substance B which is mixed with the food by tongue. The substance B contains an enzyme C which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube D. The special type of movements E in the walls of tube D push the food into stomach for further digestion. The stomach wall secretes gastric juice containing three substance F, G and H. One of the functions of F is to kill bacteria which may enter the stomach with food. The substance G protects the inside layer of stomach from the damaging effect of substance F whereas substance H is and enzyme for digestion. The partially digested food then enters into small intestine for further digestion.
An organism X having breathing organs A lives on land. When organism X goes under water, it cannot survive for a long time unless carrying an oxygen cylinder. On the other hand, the organism Y having breathing organs B always lives in water and if taken out of water, it dies after a short while. A third organism Z having breathing organs C and D which lives on the banks of ponds, lakes and rivers can survive on land as well as in water equally well.
What could organism X be? Name the breathing organs A.
What could organism Y be? Name the breathing organs B.
What could organism Z be? Name the breathing organs C and D.