Question

Which class of algae reproduces asexually by non-motile spores and sexually by non-motile gametes?
a. Rhodophyceae
b. Chlorophyceae
c. Phaeophyceae
d. Cyanophyceae

Answer 1

Hint: It is an assembly of algae composed of around 830+ genera and over 250 species. They are usually known as red algae due to the availability of a hydrophilic pigment, r-phycoerythrin. Reproduction in this species takes place by all three types: vegetative reproduction, asexual reproduction, and sexual reproduction.

Complete answer:
In Phaeophyceae, Vegetative reproduction is done by fragmentation, asexual reproduction takes place by zoospores, and Sexual reproduction arrays from isogamy to oogamy.

Chlorophyceaemembers replicate by all three kinds i.e., vegetative (cell division and fragmentation), asexual, and sexual (isogamy to oogamy).

The Cyanophyta are categorized by the complete non-availability of sexual reproduction; no sexual organs and no motile reproductive bodies have been detected. Propagation takes place by modest division, by spores, or by fragmentation (fission).

The algae which fit the group Rhodophyceae can replicate sexually as well as asexually. In asexual reproduction, the non-motile spores are formed which form the novel cell body. Sexual reproduction is the union of the non-motile gametes to produce the embryo which matures to form the new algal body.

Hence, the correct answer is option (A).

Additional information:
Reproduction in Rhodophyceae takes place by all three types: vegetative, asexual, and sexual.
- Vegetative reproduction occurs only in unicellular form.
- Asexual reproduction gets done by monospore, neutral spore, carpospore, bispore, and tetraspore.
- Sexual reproduction is of prominent oogamous type.

Note: The male sex organs are called spermatangium. Single non- flagellate male gamete is formed in each spermatangium, called spermatium. The female sex organs are known as carpogonia or in some cases, it is also called pro-carp. Carpogonia is conical flask-shaped with a wide-ranging neck, the trichogyne.