Question

What is oogamy?

Answer 1

The process of oogamy is seen in some plants and higher animals. Oogamy is a type of heterogamy or anisogamy. A variation is likely to happen in oogamy if both the gametes are non-motile.

Complete answer:
Oogamy is sexual reproduction in which the egg cells i.e. female gametes are large and non-motile and sperm cells i.e. male gametes are small and motile and, it is a type of heterogamy or anisogamy.
In oogamy the male gametes i.e. sperms are highly motile and they compete for the fertilization of the female gamete i.e. non-motile egg cell.
The ovum consists of almost all the required materials to the zygote after fertilization but it cannot move as it is non-motile. The sperm contains only the male genetic contribution which is necessary for the zygote and it usually brings the respective gametes together.
Commonly in higher animals, oogamy leads to the conclusion that the specialties of the gametes results in the better and more efficient performance of their tasks especially the ability of concentrating high energy substance in small sized ovum.
It (oogamy) occurs in animals and it is also found in many protists, algae, and in some plants such as bryophytes, ferns, and some gymnosperms like cycads and ginkgo.
There are some variations observed in algae, gymnosperms and angiosperms because the sperm cells are also non-motile.
Oogamy is seen as the evolutionary step which leads to the internal fertilization.

Note:
In oogamy female gametes are large and non-motile and male gametes are small and motile and is a type of heterogamy. It is found in many protists, algae, and in some plants such as bryophytes, gymnosperms, etc. The ovum consists of all the materials for fertilization but the sperm cells have only male genetics which is important for fertilization.