Draw a neat diagram showing fertilisation in a flower and label (a) Pollen tube, (b) Male germ cell and (c) Female germ cell, on it. Explain the process of fertilisation in a flower. What happens to the (i) ovary and (ii) ovule after fertilisation?

OR

(a) What is puberty?

(b) Describe in brief the functions of the following parts in the human male reproductive system:

(i) Testes (ii) Seminal vesicle (iii) Vas deferens (iv) Urethra

(c) Why are testes located outside the abdominal cavity?

(d) State how sperms move towards the female germ cell.

Part 1: Fertilisation in a Flower

#### Diagram of Pollen Germination and Fertilisation on Stigma

#### Explanation of the Process of Fertilisation

1. Pollination: Pollen grains from the stamen land on the sticky surface of the stigma.
2. Growth of Pollen Tube: After landing, a pollen tube grows out of the pollen grain and travels down through the style to reach the ovary.
3. Entry and Fusion: The male germ-cell travels through this pollen tube to reach the ovule inside the ovary. It enters the ovule and fuses with the female gamete (egg cell). This fusion is called fertilisation, resulting in the formation of a zygote.

#### Post-Fertilisation Changes

• (i) Ovary: Grows rapidly and ripens to form the fruit.
• (ii) Ovule: Develops a tough coat and is gradually converted into a seed.

---

OR

(a) Puberty:

Puberty is the period of adolescence during which the rate of general body growth begins to slow down, and reproductive tissues begin to mature, leading to sexual maturity and the capability to reproduce.

(b) Functions of parts in the human male reproductive system:

• (i) Testes: Produce male germ-cells (sperms) and secrete the hormone testosterone, which regulates sperm production and controls secondary sexual characteristics.
• (ii) Seminal vesicle: Secretes a fluid that provides nutrition to the sperms and makes their transport easier by providing a liquid medium.
• (iii) Vas deferens: A long tube that transports the mature sperms from the testes towards the urethra.
• (iv) Urethra: Forms a common passage for both sperms (semen) and urine to exit the body.

(c) Location of Testes:

Testes are located outside the abdominal cavity in the scrotum because the formation of sperms requires a temperature lower than the normal internal body temperature ($2\text{--}3^\circ\text{C}$ lower).

(d) Movement of Sperms:

Sperms are highly motile cells consisting of a head containing genetic material and a long tail. The tail helps them swim through the fluid medium of the female reproductive tract towards the female germ-cell (egg).