Differentiate between menarche and menopause.

Corpus luteum in pregnancy has a long life. However, if fertilisation does not take place, it remains active only for 10-12 days. Explain.

Give reasons why the human testes are located outside the abdominal cavity.

First half of the menstrual cycle is called proliferative phase as well as follicular phase. Explain.

On the basis of the functions mentioned below, identify each one correctly.

1. It helps in the movement of spermatozoan in a fluid medium.
2. It contains hydrolytic enzymes and is used to contact and penetrate the egg during fertilisation.

What is the number of chromosomes in the following cells of a human male?
Primary spermatocytes.

Draw a diagrammatic sketch of the microscopic view of a mammalian sperm and label any four parts in it.

Mention the number of cells in the following stages:

S. No	Embryonic stages	No. of cells
(i)	Zygote	______________
(ii)	Morula	______________
(iii)	Blastocyst	______________

Study the sectional view of human testis showing seminiferous tubules given below. Answer the questions that follow.
Write the functions of a and d.

Study the figure given below and answer the questions that follow:
Mention the fate of the inner cell mass after implantation in the uterus.