How does food prepared by leaves is utilized by roots? Explain.

Breathing cycle is an essential process for the exchange of gases’. Justify this statement.

There are five animals P, Q, R, S and T. The animal P always lives in water and has gills for breathing. The animal Q can stay in water as well as on land and can breathe both, through moist skin and lungs. The animal R lives in soil and breathes only through its skin. The animal S lives on land and breathes through spiracles and tracheae. And animal T lives in water and breathes through its cell membrane.

1. Which of the animals could be Amoeba?
2. Which of the animals could be frog?
3. Which animal could be fish?
4. Which animal could be grasshopper?
5. Which animal could be earthworm?

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 sometime. 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.

1. What could be X, Y and Z?
2. What is the process of converting sugar into substance Y by the action of X known as?
3. What type of respiration is exhibited by X in the above process?

Explain the process of breathing in man.

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.

1. What is Gland A, Substance B and Enzyme C?
2. Name the tube D.
3. What is the movement E known as?
4. What are F, G and H?

Distinguish between aquatic and terrestrial respiration.

What are the various components of blood? State their functions.

1. Draw the structure of a nephron and label the following on it: Glomerulus, Bowman’s capsule, Renal artery, Collecting duct.
2. What happens to glucose that enters the nephron along with filtrate?