Question

Describe reproduction by spores in Rhizopus.

Answer 1

Hint: Sexual reproduction is the process of fusion of gametes. It occurs with the help of unicellular, non-jacketed sex organs called gametangium.

Complete answer:
Rhizopus belongs to the class Zygomycetes of kingdom fungi. Zygomycetes are also known as conjugation fungi.
Reproduction by spores in Rhizopus happens in the following way:
Asexual Reproduction:
-Asexual reproduction occurs by sporangiospores and chlamydospores
-Sporangiophores are rounded bag-like structures developed on the upper end of stolon.
-Sporangia are formed which have a peripheral nucleated area known as sporoplasm and a central vacuolated area known as columelloplasm. These areas are separated by a layer of a dome-shaped vacuole. It fuses and forms a cleft
-The columella is continuous with the sporangiophore and its nucleus gradually degenerates.
-Inside the sporangium, two zones are present, soporiferous zone and central zone having dome-shaped columella.
-Soporiferous zone by the process of cleavage forms numerous polyhedral uninucleate or multinucleated structures.
-Each of these structures secretes a wall around them and develops into oval or rounded spores known as sporangiospores.
-The spores are usually multinucleated with a single layer of the wall.
-On maturation, the sporangia wall bursts, and these spores are released. They germinate when the conditions are favorable.
-Chlamydospores develop during unfavorable conditions.

-Sexual reproduction occurs by gametangial copulation. The fusion of zygophores occurs between heterothallic and homothallic species of Rhizopus.
-Vegetative reproduction occurs by fragmentation.
-Rhizopus stolonifer is also known as black mold or bread mold. Mycelium is made up of haploid hyphae.

Note: In fungi, the sexual complexity is reduced while moving from lower to higher fungi species. In the lower fungi oogamy is seen, while as we move higher anisogamy, isogamy, gametangial copulation, spermatization, and somatogamy are seen.