Question

Sexual reproduction in algae results in the formation of
(a) Oospore
(b) Zoospore
(c) Zygote
(d) Zygospore

Answer 1

Sexual reproduction in algae results in the formation of a diploid reproductive stage. It is formed by the nuclear fusion of haploid cells. This then secretes a thick wall around it. Such dormant stages also are seen in the life cycle of other protists and many fungi.

Complete step by step answer:
Sexual reproduction in algae results in the formation of zygospores.
Let us begin the explanation by understanding what algae are.
‘Algae’ is an informal term used for a large group of organisms that include diverse life forms. They are primarily photosynthetic, eukaryotic organisms. They are surrounded by a thick cell wall. It is made up of cellulose and carbohydrates. Various other chemical components like pectin, silica, and agar are also seen. They exhibit a wide range of reproductive methods like vegetative reproduction, simple asexual cell division, and complex forms of sexual reproduction.
Now let's try to learn about sexual reproduction in algae.
During the sexual reproduction of algae, two competent cells recognize each other, conjugate, and lead to fertilization. This forms a zygote, which by secreting a thick wall, acts as a penetrating spore, called ‘zygospores’, which help in penetration, dispersal, and multiplication.
So, the correct answer is, ‘(d) Zygospores.’

Additional Information:
- Many small algae reproduce asexually by fragmentation, whereas larger algae reproduce by spores.
- A few red algae produce ‘monospores’ that are carried by water currents and upon germination produce a new organism.
- Some green algae produce non- motile spores called ‘aplanospores’, while others produce ‘zoospores’, which lack true cell walls.
- The life cycles of sexually reproducing algae is variable. In some, the dominant stage is the sporophyte, while in others it is the gametophyte.

Notes:
- Zygospore is a dormant stage with a large food reservoir and thick resistant cell wall.
- Oospores are thick- walled sexual spores. They develop from a fertilized oosphere in some algae fungi and oomycetes.
- Zoospores are motile asexual spores. They use flagellum as a locomotory organ. They are also called ‘swarm spores.’
- Zygote formation is seen in Chlamydomonas during oogamy.