Growth of Pollen Tube and Fertilisation

Question 1

Describe the growth of the pollen tube and the entry of the male gamete into the ovule, followed by fertilisation

Answer 1

1. The pollen grain lands on the stigma and germinates in response to the sugary fluid secreted by stigma
2. A pollen tube grows out of each pollen grain
3. The male gamete enters the pollen tube
4. The pollen tube secretes enzymes which chemically digests the tissue of the stigma and style
5. The pollen tube grows down the style
6. The pollen tube grows into the ovary
7. The pollen tube enters the ovule through the micropyle
8. The tip of the pollen tube absorbs sap and bursts to release the male gamete
9. Fertilisation occurs - the nucleus of one male gamete fuses with the nucleus of the ovum to form a zygote

Question 2

Function of pollen tube

Answer 2

To carry the male gamete to the ovule to fertilise the ovum