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

How are fats digested in our bodies? Where does this process take place?

Describe the working of human blood circulatory system with the help of a suitable diagram which shows all the steps involved.

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

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

An organism A which cannot move from one place to another, makes a simple food B from the substances C and D available in the environment. This food is made in the presence of a green coloured substance E present in organs F in the presence of light energy in a process called G. Some of the simple food B also gets converted into a complex food H for storage purposes. The food H gives a blue-black colour with dilute iodine solution.

1. What is (i) organism A, (ii) food B and (iii) food H?
2. What are C and D?
3. Name (i) green coloured substance E, and (ii) organ F.
4. What is the process G?

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 principle of dialysis with the help of a labelled diagram.

Explain the mechanism of photosynthesis.

Describe the structure and functioning of nephrons.