Question

Which statement is true regarding the life cycle of Rhizopus and Spirogyra?
A) Asexual reproduction takes place in both by spores
B) When conjugation fails, a zygospores and parthenon spores are formed in both
C) Zygotic meiosis occurs in both
D) Sexual reproduction takes place by conjugation
E) All of the above.

Answer 1

Hint:Rhizopus is a saprophytic and parasitic fungi and is found on organic substances like - bread, jellies, fruits, vegetables, etc.Spirogyra are free-floating green algae, which are present in freshwater habitats, like - lakes, ponds, etc.

Complete answer:
>Rhizopus : In Rhizopus, Asexual reproduction occurs by the formation of sporangiospores and chlamydospores.And Sexual reproduction is by fusion of two compatible hyphae.Most of the Rhizopus species are heterothallic (which require two compatible partners to produce sexual spores).
>Spirogyra : Asexual reproduction occurs by the formation of azygospores, akinetes or aplanospores.
Zygospores are also known as parthenos pores.These are the gametes that failed to fuse during sexual reproduction and develop into a new filament asexually.
>Sexual reproduction is by conjugation.
>The zygote in Spirogyra is known as zygospore.
>Zygospores are diploid (2n) and formed by the fusion of male and female gametes.Zygospores are the only diploid stage in the life cycle of Spirogyra.
>At the time of germination, the zygospore undergoes meiosis to form 4 haploid (n) nucleus, of which only one survives and others disintegrate.

Thus the correct answer is option ‘C’.

Note:While spirogyra and rhizopus have a similarity - in both zygotic meiosis occurs, the two are different from each other when it comes to gametes.Spirogyra has multicellular gametes, while rhizopus doesn't.