A liquid X of colour Y circulates in the human body only in one direction: from body tissues to the heart. Among other things, liquid X contains germs from cells and dead cells. The liquid X is cleaned of germs and dead cells by a special type of white blood cells called Z. This cleaned liquid is then put into blood circulatory system in subclavian veins.

1. What is (i) liquid X and (ii) colour Y?
2. What are Z.
3. The liquid X is somewhat similar to a component of blood. Name this component.
4. Why is liquid X not red?

Draw a labelled diagram of the human digestive system. With the help of this diagram, describe the process of digestion of food in man (humans).

Draw the diagram of alimentary canal of man and label the following parts.Mouth, Oesophagus, Stomach, Intestine.

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.

Distinguish between photosynthesis and respiration.

Describe the alimentary canal of man.

Describe the parts of our tooth with the help of a labelled diagram.

How do carbohydrates, fats and proteins get digested in human beings?

How is double circulation different from single circulation?

Describe the exchange of gases which takes place in the leaves of a plant:

1. During daytime.
2. At night.