Question

The fungus is _____________, if it is parasitic and requires two hosts for completion of its life cycle.
A. Autotrophic
B. Autoecious
C. Heteroecious
D. None of these

Answer 1

Fungi occupy a separate position in classification of living beings. Although fungi have characteristics that are similar to both plants and animals, they are unique in many ways. The fungi are the primary decomposers of the ecosystem and may complete their life cycle either in one host or in two hosts.

Complete answer:
Option (a) is incorrect. Autotrophic organisms are capable of making their own food. Autotrophs occupy the producer level in the ecosystem. These organisms trap solar energy and utilize water from the soil, carbon dioxide from the air and form glucose. The chlorophyll pigment present in cells of green plants helps to bring about this process, called photosynthesis. Autotrophs are green plants and algae.
Option (b) is incorrect. Autoecious organisms are the ones that complete their life cycle in one host. These organisms are generally parasites that depend on other organisms to complete their life cycle. A typical example of autoecious fungi is the species of the Urediniomycetes group of fungi. Autoecious rust fungi invade plants like Chrysanthemum, Asparagus, Coffee, Bean, etc.
Option (c) is correct. The parasitic fungi that require two or more hosts to complete their life cycle are called Heteroecious fungi. The heteroecious rust fungi are Puccinia graminis, Puccinia coronata. The different hosts of these species are very difficult to identify since the types of spores released are of different and complex morphology.

Hence, the correct answer is option (C).

Note: Heteroecious fungi are the ones that require two or more hosts to complete their life cycle. The rust causing fungi can be both autoecious and heteroecious. Both species demonstrate a relationship of obligate mutualism with their hosts. The fungi that belong to the genus Puccinia are heteroecious ones that reproduce by five different types of spores. The primary host plants for Puccinia graminis are barley or wheat, while barberry is the alternate host.