What is cross pollination? Write advantages and disadvantages of cross pollination.

Hint: Pollination is the process by which pollen grains from the anther are transferred to the stigma. Anther and stigma and male and female reproductive organs of a flower.

Complete Answer:
Cross pollination is one of the two types of pollination in which the pollen grain from the anther of flower is transferred to the stigma of another flower. Examples: Apple, daffodils, etc

 There are different types of cross pollination, they are,
A. Zoophilia: In this type of pollination, animals help in facilitating the process of pollination. It happens via seed dispersal.
For example, when an animal eats a fruit and spits its seeds, it helps in dispersal of seed.

B. Anemophily: In this type of pollination, wind helps in facilitating the process of pollination. A few flowers use this method and they have characteristic features like - green, small and odourless flowers. This method occurs, when there is absence of pollinators, and as the flowers are odourless, they don't attract any insect.
Examples - Coconut, maize, etc
- The male flowers produce a huge amount of pollen which is very light in weight and in the female flowers the stigma is very large, feathery and sticky and extends outside the flower for the pollen to come and stick.

C. Anthropophily: It is an artificial mode of pollination as it is done by humans by spreading pollen grains over the female flowers. Hybridization techniques are also used.

The advantage of cross pollination are:
- Unisexual plants can reproduce with the help of cross pollination.
- It helps in the introduction of new genes into a sequence of species.
- It helps in improving the immunity of offspring against environmental stress and diseases.

The disadvantage of cross pollination are:
- Huge amounts of pollen grains are wasted.
- There is a chance of genetic recombination which can lead to elimination of good qualities of the parent.

Note: The other type of pollination is, self pollination. In this process the pollen grain produced in anther falls directly into the stigma of the same flower. It generally occurs in bisexual flowers.