Self-pollination & Cross-polination

Biology: Cambridge International GCSE Supplement, topic 16.3.3

Pollination

Pollination is the transfer of pollen grains from the male anther to the female stigma. Pollination can happen in different ways:

Self pollination happens when pollen from an anther is transferred to the stigma of the same flower, or a different flower on the same plant.
The offspring produced are identical to the parent plant, so a disadvantage of this is a lack of genetic variation in the offspring.
An advantage of this is that if a plant is not able to reproduce by cross-pollination (for example there are no pollinators nearby), they can still reproduce through self-pollination.

Cross-pollination is the transfer of pollen from the anthers of one flower to the stigma of a flower on a different plant.
This introduces genetic variation into the offspring, so they are more able to respond to environmental changes.

After pollination, a structure called a pollen tube grows out of the pollen grain down the style.
The male gamete travels down the pollen tube to the ovule inside the ovary.
Fertilisation is when the nucleus of a male gamete fuses with the nucleus of a female gamete (the ovule).