Differentiate between thigmotropic and chemotropic movement.

Write any two postulates of Darwin's theory.

A red coloured pigment A is found in the blood of vertebrates and a few invertebrates. A blue coloured respiratory pigment B is found in the blood of several invertebrates. Name A and B.

Given below is a diagram representing the structure of an ovum surrounded by a few sperm cells. Study the diagram and answer the questions that follows.

(a) Where does fertilisation, normally take place?

(b) Mention the chromosome number in egg and zygote in humans.

(c) What is the main function of corona radiata?