Question

How is pollination different from fertilisation?

Answer 1

Seed producing plants have a process of sexual reproduction, which involves a male gamete or nucleus fusing with a female gamete or nucleus to form zygote. In this case, it is a pollen grain fusing with the ovule.

Complete answer:
In order for fusion of the haploid male and female gametes to take place, they have to first get into close proximity. Pollen grains are formed in the anthers of the flower. These may be the same flower, different flowers on the same plant, or different plants together. Either way, the pollen grains transfer to the stigma of the flower. This may take place through several ways, including transfer by insects, by wind, and artificially. This process of transferring the pollen from the male anther to the female stigma is called pollination.

For fertilisation, the pollen grain or microspore transfers the male sperm cell to the egg cell in the ovule. This usually involves a pollen tube extending down through the staminal tube, till it makes contact with the ovule and the male gamete then fuses with the egg. This forms the diploid zygote. The polar nuclei in angiosperms fuse with the second male nucleus to form the triploid tissue that gives rise to the endosperm of the seed.

So pollination is the transfer of the pollen to the stigma, and fertilisation is the fusion of the male haploid gamete with the female haploid gamete.

Note: When pollination is from the same flower or a flower on the same plat it is called self-pollination, when it is from a flower on a different plat, it is cross pollination. Angiosperms have double fertilisation, gymnosperms have singles.