1. What is the function of pollen grains in flower ?
2. Why is regeneration considered a method of reproduction ?
3. What does DNA copying mechanism create ?
4. What happens if the ovum is not fertilised ?

1) 

The function of pollen grain is to transfer the male reproductive cell or the gametes to the female reproductive cell or the ovule. To facilitate sexual reproduction to take place.

2) 

In lower organism like Planaria and Hydra it is a method of reproduction because the whole new organism is develop from the cut body parts through the process of growth and development.

4)

If the ovum is not fertilized it will disintegrate and be passed out of the female body as menstrual flow. The menstrual flow along with blood also contain the disintegrate egg.