(A) What are protozoans ? Give two examples each of free-living and parasitic forms.
(B) What are slime-moulds ? How are they different from true fungi ? Give one example each of the cellular and ascellular slime and moulds.
(C) Differentiate between ascus and basidium.

Explanation

(A) Protozoans are unicellular protist animals. Each protozoans is microscopic organism in which a single cell performs all the vital activities. Examples of free living protozoans are Amoeba and Paramoecium. Example of parasitic forms are Trypanosoma and Plasmodium.
(B) Slime moulds are consumer decomposer protists which occur in the form of slimy masses during vegetative phase. The vegetative parts do not possess cell walls and, therefore, they occur either as free-living multinucleate amoeboid mass of protoplasm (plasmodium) or aggregation of amoebae (pseudoplasmodium). Example of cellular slim mould is Dictyostrelium and that of acellular slime mould is Physarum.
(C) The main differences between an ascus and a basidium are -(i) Ascus is formed in ascomycetes whereas basidium is formed in basidiomycetes, (ii) Ascus encloses 8 ascospores which are borne endogenously. The basidium produces 4 basidiospores which are borne exogenously, (iii) The basidiospres are attack basidia by means of sterigma whereas ascospores are filled inside the sac like ascus.