Question

Ainsworth has placed Rhizopus in ________.
A. Zygomycetes
B. Mastigomycotina
C. Ascomycotina
D. Myxomycota

Answer 1

Hint:- Rhizopus is a genus of multicellular fungi that are saprophytic in nature. They grow on dead decaying organic matter and are found to parasitize animals too. They have a characteristic filamentous body that includes a long stolon, pigmented rhizoids, and unbranched sporangiophores (single or in clusters). Rhizopus stolonifer is a common bread mold.

Complete step-by-step solution:-
Ainsworth G. C. is mainly remembered for his famous classification of fungi. In 1973, he proposed a
natural system of classification based on morphology and reproductive biology of fungi. He included
fungi and slime molds together in the kingdom Mycota. Subsequently, he placed Rhizopus in the
Class Zygomycetes. Zygomycetes is a class of pin molds and belongs to Eumycota or true fungi. They
are terrestrial fungi that are free-living, saprotrophic, or parasitic. Few genera are unicellular while
most are filamentous. They are devoid of chlorophyll. Their cell wall is non-cellulosic and its
composition varies as they may contain chitin, chitosan, or glucan. They have reserve food material
in the form of oil, mannitol, and glycogen.
The Rhizopus thallus is haploid and consists of coenocytic (multinucleated and aseptate) mycelium.
The mycelium is found immersed in the host tissue. They do not have motile cells. Reproduction
takes place by both modes i.e. asexual as well as sexual. During, sexual reproduction gametangial
conjugation occurs to form diploid spores called zygospores.
So, the correct answer is option (A), Zygomycetes.

Additional information:-
Rhizopus sp. are known to be opportunistic fungi as they cause infections like Zygomycosis or Mucormycosis.

Note:- Rhizopus reproduce vegetatively also by fragmentation. Each stolon fragment develops separately to form a complete mycelium. They reproduce asexually by sporangiospores and chlamydospores.