Question

A phenomenon is termed as parthenogenesis when
(a) Artificial fertilization occurs
(b) Egg is fertilized by a sperm
(c) Egg undergoes cleavage without fertilization
(d) Sperm dies before fertilization

Answer 1

Generally, it is a natural form of asexual reproduction in which the growth and development of embryos can take place without fertilization by sperm. It occurs naturally in some plants and some invertebrate animal species. It can also occur without meiosis through mitotic oogenesis.

Complete answer:
Parthenogenesis is the process in which the formation of the organism from an unfertilized egg. The term parthenogenesis was coined by Charles Bonnet. It is also called the virgin birth. Parthenogenesis is of the following three kinds:

1. Arrhenotoky: male develops parthenogenetically.
2. Thelytoky: Female develops parthenogenetically.
3. Amphytoky: Parthenogenesis brings about any sex depending upon ecological conditions.

Additional Information: Parthenogenesis is in some cases viewed as an asexual type of reproduction; although, it might be all the more precisely described as an "incomplete type of sexual propagation," since offspring of parthenogenically species create from gametes. Gametes are receptive cells that result from meiosis (or reductional division), in which a specific cell with a (diploid) double set of chromosomes goes through two fissions of its nucleus. Meiosis offers ascend to four gametes, or sex cells, which are haploid, in that each possesses half the number of chromosomes of the original cell.
So, the correct answer is ‘Egg undergoes cleavage without fertilization’.

Note: Parthenogenesis can operate on either a haploid or a diploid cell. In haploid parthenogenesis, an uncommon type of parthenogenesis that happens in a couple of types of honey bees, nematodes, and plants, offspring are created from haploid eggs to deliver haploid adults. Then again, the cycle of diploid parthenogenesis, a more common and varied form of the phenomenon, may continue along two pathways. Automixis (automictic parthenogenesis) is a postmeiotic cycle in which a haploid cell may either copy its chromosomes or get together with another haploid cell. The second type of diploid parthenogenesis, apomixis, forgoes complete meiosis altogether.