Question

The common mode of sexual reproduction in Chlamydomonas is:
A. Isogamous
B. Anisogamous
C. Oogamous
D. Hologamous

Answer 1

Hint: The reproduction is the process of producing offspring of the same species. There are basically two modes of reproduction – asexual and sexual reproduction. In asexual reproduction, the young ones are produced without the process of fertilization whereas in sexual reproduction two parents fuse via process of fertilization to form an offspring.

Complete answer:
Fertilization is the process in which two gametes, preferably male and female gametes fuse to form a single cell called zygote which develops into embryo and later into a complete organism. The Chlamydomonas is a unicellular, biflagellate organism belonging to the green algae inhabiting freshwater and sea. The mode of reproduction in Chlamydomonas is asexual as well as sexual. In asexual reproduction, the Chlamydomonas produce:
Zoospores are the spores that are produced in favorable conditions and give rise to new organisms.
Aplanospores are produced in slightly favorable conditions and the parent loses its flagella during this time.
Hypnospores are the thick-walled spores that are produced during extremely unfavorable conditions.
Chlamydomonas sexually reproduces through the involvement of two gametes:
Isogamy: Both of the gametes that are produced are similar in shape, size and structure. These are morphologically similar but physiologically different. Also, Isogamy is most common in sexually reproducing Chlamydomonas.
Anisogamy: In this type of sexual reproduction, both the gametes are dissimilar morphologically. The male gametes are smaller in size and female is larger.
Oogamous: It is the type of reproduction in which the male gamete is smaller and motile but female is larger but non-motile in nature. Male gamete comes closer to female gamete and fuse.
Hologamy: in this type of reproduction, both the male and female gametes resembling the somatic cells fuse to give rise to young one.

Therefore, the correct answer for this question is Isogamous that is option A.

Note: In asexual reproduction, only single parent produces the offspring without involvement of process of fertilization and the offspring completely resembles the parent. But, in sexual reproduction, offspring is produced as a result of fertilization and it is not completely identical to a single parent, but contains the characteristics of both the parents.