Question

Metagenesis refers to

• A. occurrence of a drastic change in form during post-embryonic development
• B. presence of a segmented body and partheno- genetic mode of reproduction
• C. presence of different morphic forms
• D. alternation of generation between asexual and sexual phases of an organism.

Answer 1

The Correct Option is D

To solve the given question, let's understand what "Metagenesis" refers to in biological terms.

Metagenesis is the phenomenon of alternation of generations, which is a biological process common in the life cycle of certain organisms, especially plants and some invertebrates. It involves the alternation between two generations: one that reproduces sexually and another that reproduces asexually.

Let's analyze the options given:

1. Occurrence of a drastic change in form during post-embryonic development.

   This option describes metamorphosis, not metagenesis.

2. Presence of a segmented body and parthenogenetic mode of reproduction.

   This option describes some aspects of animal anatomy and reproduction but not related to metagenesis.

3. Presence of different morphic forms.

   While this might seem related, it does not specifically describe metagenesis. It could refer to polymorphism.

4. Alternation of generation between asexual and sexual phases of an organism.

   This is the correct definition of metagenesis. Some organisms switch between two distinct forms of reproduction, one asexual and one sexual.

Thus, the correct answer is: alternation of generation between asexual and sexual phases of an organism.

Metagenesis is prominently observed in the lifecycle of organisms such as cnidarians, bryophytes, ferns, and some algae. For example, many cnidarians alternate between a polyp (asexual) phase and a medusa (sexual) phase.