Question

Gynogenesis is shown by
A)Nematodes
B)Few annelids
C)Both A and B
D)None of the above

Answer 1

Hint: Gynogenesis a type of parthenogenesis which involves development of female gametes without any fertilisation.Gynogenesis is a type of asexual reproduction. It requires the sperm but it does not contribute its DNA for completion. The gynogenic animals are unisexual.

Complete answer:
The gynogenic animals are mostly the unisexual animals which reproduce asexually. The male sperm is required but does not contribute to DNA. The paternal DNA dissolves and is destroyed before it fuses with the egg. The female gamete develops, unfertilised and develops into an adult and has only maternal DNA. The mating takes place with the males of closely related bisexuals. This type of reproduction takes place in fishes (Pisces) and amphibians (Amphibia), some Nematodes.

Nematode-It includes roundworm, tapeworm. They have a well developed reproductive system. The nematodes are proper females and males. The females lay eggs and it gets fertilised by the males. But in some cases, the eggs get fertilised without fertilisation. The eggs hatch into young nematodes which resemble the adult nematode.

Annelids- Annelids are organisms like earthworms. They are hermaphrodites. They reproduce both sexually and asexually. Asexual reproduction takes place by budding and fission. Sexual reproduction does not take place by self-fertilisation. In some annelids, the female gametes develop into adults without fertilisation by the male gamete. It is called gynogenesis.

Hence, the correct answer is option (C)

Note: It is also known as virgin birth. The disadvantage of this mode of reproduction is the male DNA is not passed on to the off-springs. It is an intermediate between sexual and asexual reproduction.