Question

List two reasons for the appearance of variations among the progeny formed by sexual reproduction.

Answer 1

Reproduction is the process through which one organism produces their offspring to maintain their number on Earth. Some of the organisms undergo sexual reproduction and some undergo asexual reproduction.

Complete Answer:
- We should know about reproduction as reproduction is the life process of organisms that helps them to grow the population. The reproduction ensures the continuity of organism generation to generation. The reproduction is of two types; asexual reproduction and sexual reproduction.
- Asexual reproduction is a process of reproducing the offspring through simple division of cells, this type of reproduction is observed in single cell organisms, it does not undergo fusion of gametes therefore, and the offspring produced by asexual reproduction are genetically identical.
- The asexual reproduction is further divided into; binary fission, budding, fragmentation, and sporogenesis. Sexual reproduction is a process of reproduction of offspring through gamete fusion of male and female organisms.
- The gametes are either formed in different individuals or the same individual. This is a complex and slow process that produces genetically diverse organism’s multicellular organisms like humans undergo sexual reproduction. Plants are also multicellular organisms but they undergo both sexual and asexual mode of reproduction.
- The vegetative mode of reproduction is the asexual reproduction that is the formation of a complete plant from stem, tuber, corm, and stolon. The sexual reproduction in plants takes place through the pollination process. The pollen grains are the male gametes of a plant that when fall on the stigma results in the formation of pollen tube that reaches to the female gametes that is the ovary and fusion of gametes takes place and seed is formed.
- Now, the two major reasons for appearance of variation among the progeny formed from sexual reproduction are; crossing over in which the DNA gets exchanged between the homologous chromosomes during the meiosis that causes variation in the offspring. The individual formed from the sexual reproduction has characteristics from father as well as from the mother and because of this difference in the characteristics variations occur among the progeny.

Note: Asexual organisms do not show variation as the progeny receives the characteristics from a single parent and this results in the transfer of similar characteristics from generation to generation.