Which of the following algae shows physiological anisogamy?
A. Spirogyra
B. Ulothrix
C. Volvox
D. All of these
VerifiedHint: The algae are the group of eukaryotic organisms that have their own photosynthetic pigment and are eukaryotic organisms. These can be unicellular or multicellular and are mostly autotrophic in nature. These are capable of producing their food.
Complete answer:
These organisms inhabit aquatic environment either freshwater or marine life. These organisms may be flagellates or amoeboid and colonial in nature.
Further, anisogamy is the phenomenon in which the fertilization occurs between two gametes which are unequal in size. Out of which the male gamete is smaller in size and female gamete is comparatively larger. Anisogamy may be of several types like both gametes may be flagellated and motile or both may be non-motile.
Now we have been asked about the organism in which anisogamy occurs, we shall now discuss the sexual reproduction in all organisms and conclude the answer.
In spirogyra, asexual reproduction occurs by the process of fragmentation and sexual reproduction occurs with the process of conjugation. In conjugation two fragments get attached and reproduce by the help of a conjugation tube which is formed between them. The transfer of genetic material occurs from one strain to another strain via conjugation tube, out of which one is considered as male and other is considered as female. Usually, the motile one is considered as male and non-motile is considered as female. The genetic material of male gets transferred to the female and fuses with the genetic material of females thus causing fertilization. After the course of fertilization, the diploid zygote is formed in which meiotic division occurs for the generation of a haploid young one.
Ulothrix is a member of green algae which is commonly found in marine life and fresh waters. Ulothrix reproduces asexually by fragmentation and by non-motile spores and sexually by the formation of flagellated gametes which are morphologically same. Thus, sexual reproduction in Ulothrix is isogamous.
Volvox is an algae growing usually in stagnant water or rivers. The sexual reproduction in volvox is an oogamous type. Thus, two morphologically dissimilar gametes are produced.
Therefore, the correct answer is spirogyra.
Note: The sexual reproduction in algae is known to be of three types: isogamous, anisogamous and oogamous. The gametes produced by the isogamous reproduction are morphologically similar whereas the gametes produced by anisogamous reproduction are morphologically different in which the female gamete is larger than the male gamete. In an oogamous type of reproduction the gametes produced are different in which the female is larger than the male and is non-motile whereas the male gamete is motile.
