The organs A of a person have been damaged completely due to which too much of a poisonous waste material B has started accumulating in his blood, making it dirty. In order to save this person's life, the blood from an artery in the person's arm is made to flow into long tubes made of substance E which are kept in coiled form in a tank containing solution F. This solution contains three materials G, H and I in similar proportions to those in normal blood. As the person's blood passes through long tubes of substance E, most of the wastes present in it go into solution. The clean blood is then put back into a vein in the arm of the person for circulation.

1. What are organs A?
2. Name the waste substance B.
3. What are (i) E and (ii) F? Name G, H and I.
4. What is the process described above known as?

What is the main difference between aerobic respiration and anaerobic respiration? Give one example of each.

Outline the functioning of kidney dialysis machine?

The organisms A, B and C can obtain their food in three different ways. Organism A derives its food from the body of another living organism which is called its D, without killing it. The organism B takes in the solid food by the process of ingestion, digests a part of this food and throws out undigested food in the process called E. The organism C obtains its food from dead and decaying plants.

1. What is the mode of nutrition of (i) organism A (ii) organism B, and (iii) organism C?
2. What is the organism like D called?
3. Name the process E.
4. Give one example each of organisms like A, B and C.
5. What is the general name of three modes of nutrition exhibited by organisms A, B and C?

Explain the mechanism of photosynthesis.

Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it, Lung capillaries, Pulmonary artery to lungs Aorta to body, Pulmonary veins from lungs.

Distinguish between photosynthesis and respiration.

Name the main organs of the human digestive system in the order they participate in the process of digestion. Describe how digestion of carbohydrates and proteins take place in our body.

Second stage of urine formation is called selective re-absorption. Why?

If the teeth are not cleaned regularly, they become covered with a sticky yellowish layer W of food particles and bacteria. Since layer W covers the teeth, the alkaline liquid X secreted by glands Y inside the mouth cannot reach the teeth surface to neutralise the acid formed by the action of organisms Z on sugary food, and hence tooth decay sets in.

1. What is W known as?
2. What is (i) X, and (ii) Y?
3. What are organisms Z?
4. State one way of removing layer W from the teeth.