Explain the process of digestion of food in mouth, stomach and small intestine in human body.

Describe the alimentary canal of man.

Valves are present in between the auricles and ventricles of the heart. Give one reason.

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

Draw a diagram of the human heart and label its parts.

State the location of salivary glands.

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.

The partially digested food coming from the stomach of a person enters a long and narrow organ A in his body. The organ A receives the secretion of two glands: liver and pancreas. Liver secretes a greenish - yellow liquid B which is normally stored in the organ C. Pancreas secretes pancreatic juice which contains three digestive enzymes D, E and F. The intestinal juice completes the process of digestion of food. The inner wall of organ A has millions of tiny finger - like projections G which help in the rapid absorption of digested food into blood stream. The undigested part of food then passes into wider tube H which absorbs most of the water from undigested food. The last part of tube H called I stores this undigested food (or waste) for some time. The undigested food is then passed out though opening J as faeces in the process known as K.

1. Name the organ A.
2. Name liquid B and organ C.
3. What are the digestive enzymes D, E and F?
4. Name the projections G present on the inner wall of organ A.
5. Name Tube H, Part I, Opening J and Process K.

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

1. Glucose → Respiration → Respiration Ethanol + Carbon-dioxide + Energy.
2. Glucose → Respiration → Respiration Carbon-dioxide + Water + Energy.
3. Glucose → Respiration → Respiration Lactic acid + Energy.

1. Name one organism which respires according to equation (i) above.
2. Name one organism which respires according to equation (ii) above.
3. When and where does respiration represented by equation (iii) above take place?
4. Which equation/ equations represent aerobic respiration?
5. Which equation/ equations represent anaerobic respiration?
6. Which of the above reactions produces the maximum amount of energy?

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?