Question

why cannot fertilisation take place in flowers if pollination does not occur

Answer 1

Pollination is the process of transferring of male gamet to female gamet of a flower of same specie.
Fertilization means fusion of gamets.
Fertilisation occurs after the process pollination.
So , fertilization donot occurs if pollination donot occur.

Answer 2

fertilisation means fusion of the two gametes while pollination means the transfer of pollen grains from the anther of the flower to the stigma of that same flower or other flower of the same kind.

therefore after pollination fertilisation occurs so how can fertilisation occur without pollination.

any doubt ask me questions .

hope this will help you