Question 17.
Explain sexual reproduction in plants.
Answer:
1. Sexual reproduction in plants involves pollination and fertilization. Pollen grains from anther are transferred to the stigma. This is called as pollination.
2. Pollination requires abiotic agents (wind, water) and biotic agents (insects and other animals). Stigma becomes sticky during pollination. Pollens germinate when they fall upon such sticky stigma i.e. a long pollen tube and two male gametes are formed.
3. The pollen tube carries male gametes. Pollen tube reaches the embryo sac via style. Tip of the pollen tube bursts and two male gametes are released in the embryo sac. One male gamete fuses with the egg cell to form a zygote. This is fertilization. Second male gamete unites with two polar nuclei and endosperm is formed. As two nuclei participate in this process, it is called as double fertilization.
