What is menstrual cycle? Name the hormones which control the menstrual cycle.

OR

Draw a labelled diagram of the sectional view of mature pollen grain angiosperms. Explain the functions of different parts.

The reproductive cycle in the female primates (e.g. monkeys, apes and human beings) is called menstrual cycle. Menstrual cycle is regulated by pituitary hormones (FSH and LH) as well as ovarian hormones (oestrogen and progesterone). FSH helps in growth of the follicles. LH and estrogen cause ovulation (release of ovum from the Graafian follicle). Progesterone helps in the thickening of the of the endometrium. Fall in progesterone levels cause menstruation.

OR

 

Functions of different parts of pollen grains are:
1. Exine: This is outermost layer of pollen grain which provide protection from mechanical injury and made up of sporopollenin which is one of the most resistant organic material. It can withstand high temperatures, strong acids and alkali. Have germ pores on the surface for outgrowth of pollen tube.
2. Intine: It is made up of pecto-cellulose and leads to the formation of pollen tube. It is a thin and continuous layer. 
3. Vegetative cell: Contains food reserve and have large nucleus. Help in the movement of male gametes in the pollen tube.
4. Generative cell: The generative cell is small and floats in the cytoplasm of the vegetative cell. It is spindle shaped with a dense cytoplasm and a nucleus. It produces two male gametes by mitosis.