Answer:
1. Having two similar gametes in which no differentiation can be distinguished, or reproducing by the union of such gametes.
e.g. in Spirogyra and Ulothrix
2. Anisogamy refers to a type of sexual reproduction in which two dissimilar gametes unite or fuse. The gametes may differ in size or form.
Example : human beings, the male gamete sperm is smaller and motile while the female gamete egg is non motile and larger.
3. having or involving a small motile male gamete and a large immotile female gamete.
E.g. Volvox, Fucus