Q.Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.

Algae reproduce asexually by producing different kinds of spores depending on the surrounding conditions.

• Zoospores: motile (flagellated) spores produced under favourable, sufficiently moist conditions; they swim away using their flagella and germinate directly into new algal filaments/thalli.
• Aplanospores: non-motile spores (lacking flagella) that some algae produce instead of zoospores when conditions are somewhat less favourable for motile spore formation, but not yet severe enough to demand a resting stage. …

Algae, like the Phycomycete fungi covered elsewhere in this chapter, do not produce just one fixed kind of asexual spore — the type of spore formed shifts with the surrounding environmental conditions, so that the alga always has a strategy suited to the situation it is in.

Zoospores, formed under favourable conditions (adequate moisture and nutrients), are the most common asexual spore in algae. They are motile — each spore bears one or more flagella that let it actively swim through water — and once released from the parent thallus, a zoospore settles down, loses its flagella, and germinates directly into a new algal filament or thallus. Because they need water to swim in, zoospore production depends on the alga being sufficiently wet.

Aplanospores are produced when conditions are less consistently favourable for motile spore formation. These spores are non-motile — they lack flagella entirely — but they are still relatively thin-walled and, like zoospores, germinate fairly promptly into new individuals rather than lying dormant. …