Question

A Chlamydomonas plant is left exposed in the mud. What would be its means of survival?
A. Formation of aplanospores
B. Palmella stage
C. Formation of hypnospores
D. All of the above

Answer 1

Hint:-In soil, ponds, and ditches, Chlamydomonas, a genus of biflagellate single-celled green algae grows. The species of Chlamydomonas can become so abundant as to colour the freshwater green. Although photosynthesis occurs, the surface of the cell may also absorb nutrients. Asexual reproduction is carried out through zoospores. Gametes are formed by sexual reproduction.

Complete Answer:-Aplanospores - Aplanospores are asexual spores present in many algae and fungi that are nonmotile. They are produced from a portion of a vegetative cell's protoplast. Aplanospores are made up of a cell wall that differs from the original parental cell wall. They help an organism to survive in a slightly unfavourable condition.
Palmella stage - A stage in some single-celled flagellate algae's life history in which the cells lose their flagella and form a gelatinous aggregation. Under unfavourable conditions, the palmella stage is formed, such as water scarcity. To produce several daughter protoplasts, the parent cell protoplast breaks, but they do not form zoospores. To build a mucilaginous sheath around the daughter protoplasts, the parent cell wall gelatinizes. It is commonly seen in Chlamydomonas and euglena. They are mainly produced in water and nutrient deficit conditions.
Hypnospores in Chlamydomonas is non-motile asexual spores that have thickened. In Chlamydomonas, they indulge in asexual reproduction. To form the hypnospores, the aplanospores develop a thick wall.

So, the correct answer is ‘Palmella stage’, option (B).

Note:- Under favourable conditions, Chlamydomonas reproduce asexually by zoospores formation. In structure but smaller in size, the zoospores are identical to the parent cell. To become mature Chlamydomonas, the zoospores simply enlarge. The formation of zoospores can occur every 25 hours under favourable conditions.