Question

Metagenesis refers to
A. Presence of a segmented body and parthenogenetic mode of reproduction.
B. Presence of different morphic forms.
C. Alternation of generation between asexual and sexual phases of an organism.
D. Occurrence of drastic change in form during post embryonic development.

Answer 1

Hint: Cnidarians show this type of lifespan with two forms- polyps and medusa, where polyps produce medusa asexually and medusa produce polyps sexually.

Complete Answer:
- Alternation of generations is a cycle of life that takes place in those plants and algae in Archaeplastida and Heterokontophyta that have different sexual haploid and asexual diploid stages.
- In these groups of plants, a multicellular haploid gametophyte that has 'n' chromosomes can alternate with a multicellular diploid sporophyte that has '2n' chromosomes. A mature sporophyte produces haploid spores by a process that reduces the number of chromosomes by half from 2n to n. This process is known as meiosis.
- Alternation of generations is also termed as metagenesis or heterogenesis, in biology. The alternation of generation is the sexual stage and the asexual stage of the lifespan of an organism.
- These two generations or phases are often morphologically and sometimes chromosomally well defined. So, we can say that metagenesis refers to the alternation of generation between sexual and asexual stages of an organism.

Thus, the correct answer is option C i.e., Alternation of generation between asexual and sexual phases of an organism.

Note: Some plants alternate between diploid sporophyte and haploid gametophyte, as well as between asexual and sexual reproduction. As a result, the life cycle of these plants is known as generational alternation.