Question

Heterothallism is found in:
a. Mucor
b. Cycas
c. Selaginella
d. Volvox

Answer 1

Hint: In Heterothallism, fungi having mycelia of two unlike types, both of which must participate in the sexual process. Heterothallic species have sexes that present in different bodies. For separating heterothallic fungi, the two compatible partners are needed to produce sexual spores, from homothallic ones and they can reproduce sexually from a single organism.

Complete answer:
> Mucor is a heterothallic fungus. In heterothallic species of Mucorales, sexual reproduction occurs when opposite mating types come into proximity, inducing the formation of specialized hyphae called gametangia. The gametangia grow toward each other to fuse and further, it begins to form a diploid zygote at the point of fusion.

> Cycas is a genus of plants related to a very ancient lineage, the Cycadophyta. Cycas is the type genus and it is the only genus found in the family Cycadaceae.

> Selaginella is the single genus species of vascular plants in the family Selaginellaceae, the spikemosses, or lesser club mosses.

> Volvox is a polyphyletic genus of chlorophyta green algae found in the family Volvocaceae.

Hence, the correct answer is option (A).

Note: In 1904, Blakeslee discovered the term heterothallism which is used for the condition of sexual reproduction in many species of Mucorales, and the ‘conjugation is possible only through the interaction of two differing thalli’. It is believed that the term morphological heterothallism can be applied and that those species in which the unlike thalli differ by an incompatibility factor can be considered to exhibit physiological heterothallism. In Mucorales, there is no formation of zygospores.