Name some animals in which internal fertilisation occurs.

a) What is fertilisation? Distinguish between external fertilisation and internal fertilisation. What is the site of fertilisation in human beings. b) How does growing embryo get nutrition from the mother's blood?

Give any four differences between external and internal fertilisation?

Give reasons for the following: Compared to internal fertilization, external fertilization is disadvantageous to the animal.

Name the animal in which sex is determined by number of chromosomes. Who produced the first induced mutation?

When and why do some animals like snails undergo aestivations?