Question

There is a true alternation of shown by cnidarians called as-
(a)Metachrosis
(b)Metagenesis
(c)Metamorphosis
(d)Metaboly

Answer 1

Hint: The type of life cycle that occurs in those plants with distinct haploid sexual and diploid asexual stages is generation alternation. Cnidarians exist in 2 forms- polyp and medusa through alternation cycles.

Complete answer:
Cnidarians (particularly among Hydrozoa) reproduce asexually through budding. Cnidarians are also capable of sexually reproducing. The alternation of generations, in which asexually reproducing generations overlap with sexually reproducing generations, is a feature here. This unique process of generation alternation is known as metagenesis.
A multicellular haploid gametophyte with n chromosomes alternates with a multicellular diploid sporophyte with 2n chromosomes, consisting of n pairs in these groups. By meiosis, a mature sporophyte creates haploid spores, a mechanism that decreases the number of chromosomes by half, from 2n to n.
The haploid spores germinate into a haploid gametophyte and develop into it. The gametophyte develops gametes at maturity through mitosis, which does not affect the number of chromosomes. Two gametes fuse to create a diploid zygote, which grows into a diploid sporophyte (originating from various organisms of the same genus or from the same organism). This cycle is the manner in which all land plants and many algae undergo sexual reproduction, from gametophyte to sporophyte (or from sporophyte to gametophyte equally).

Additional Information: The interaction between the sporophyte and the gametophyte differs between different plant groups. The sporophyte and gametophyte are distinct individual species of those algae with alternating generations, which may or may not have a similar appearance.
So, the correct answer is ‘metagenesis’.

Note: Cnidaria has no heart or lung organs. They have an inner cavity used for breathing and a mouth-based gastrovascular cavity (a "stomach"), but they do not have an anus. Other essential functions occur by diffusions, such as respiration and excretion.