Question

The protonema in early development stages of moss resemble green filaments of algae, thus favouring
A. Recapitulation theory
B. Homology
C. Atavism
D. All of the above

Answer 1

A protonema is a thread-like structure made up of cells, which makes up the earliest stage in the life cycle of mosses, belonging to division Bryophyta. The structure resembles the filamentous arrangement present in algae.

Complete step by step answer:
Recapitulation theory is also known as biogenetic law, hypothesizes that the embryonic development of an organism from the fertilization stage goes through different phases which resembles the evolutionary pattern of the ancestors of the organism. Here ontogeny repeats phylogeny, where ontogeny is the life history of the individual organism and phylogeny is the evolutionary history of the organism. Thus, the appearance of protonema which is filamentous during its developmental stage with its similarity to its algal ancestors belongs to the green filamentous algae.
Considering the other options:
Homology: The branch of study in determining the similarities between various organisms to study about the common ancestors present. It can be either studied based on development, functions and genetics. Homologous organs are therefore the organs which have the same ancestral origin but perform different functions.
Atavism: The presence of an ancestral genetic trait after being lost through an evolutionary change in the preceding generations. It can happen when the genes responsible for the particular phenotype gets preserved in the DNA and gets exposed though some kind of mutation which happened. The phenomena of atavism can be seen as an evidence of evolution. An example of atavism can be observed with the presence of limbs in limbless vertebrates.
Thus from the above given options, the most appropriate option was found to be A, that is the Recapitulation Theory.

Note:
The theory of recapitulation is also known as embryological parallelism. The theory was expressed using Earnest Haeckel’s proposed theory ontogeny recapitulates phylogeny. It was formulated by Etienne Serres in the year 1820.