When a person breathes in air, the air enters into his body through an organ A having two holes B in it. The air then passes through pharynx and larynx and enters into a tube C. The tube C divides into two smaller tubes D at its lower end. The two smaller tubes are attached to two respiratory organs E. Each smaller tube divides inside the organs E to form a large number of still smaller tubes called F. The smallest tubes F have air-sacs G at their ends in which gaseous exchange takes place in the body of the person. What are A, B, C, D, E, F and G?

Some sugar solution is taken in a test-tube and a little of substance X in powder form is added to it. The mouth of test-tube is closed with a cork and allowed to stand for some time. On opening the cork, a characteristic smell of substance Y is obtained and a gas Z is also observed to be formed. The gas Z extinguishes a burning matchstick.

(a) What could be (i) X, (ii) Y, and (iii) Z ?

(b) What is the process of converting sugar into substance Y by the action of X known as? (c) What type of respiration is exhibited by X in the above process ?

Consider the following chemical reactions which take place in different organisms/tissues under various conditions:

(i) Glucose Ethanol + Carbon dioxide + Energy

(ii) Glucose Carbon dioxide + Water + Energy

(iii) Glucose Lactic acid + Energy

(a) Name one organism which respires according to equation (i) above.

(b) Name one organism which respires according to equation (ii) above.

(c) When and where does respiration represented by equation (iii) above take place?

(d) Which equation/equations represent aerobic respiration ?

(e) Which equation/equations represent anaerobic respiration ?

(f) Which of the above reactions produces the maximum amount of energy ?

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.

(a) What could organism X be ? Name the breathing organs A.

(b) What could organism Y be ? Name the breathing organs B.

(c) What could organism Z be? Name the breathing organs C and D.

(d) Out of X, Y and Z, which organism is (i) amphibian, (ii) aquatic, and (iii) terrestrial ?

What is the name of tissues which transport:

(a) food in a plant?

(b) water and minerals in a plant?