Biological Classification Question 138
138. Most of the Lichens consist of
(a) blue-green algae and basidomycetes
(b) blue-green algae and ascomycetes
(c) red algae and ascomycetes
(d) brown algae and phycomycetes
Show Answer
Answer : b
Hints & Solutions
(b) The lichen fungus is typically a member of the Ascomycota, rarely a member of the Basidiomycota. The algal or cyanobacterial cells are photosynthetic, and as in higher plants they reduce atmospheric carbon dioxide into organic carbon sugars to feed both symbionts. Both partners gain water and mineral nutrients mainly from the atmosphere through rain and dust. The fungal partner protects the alga by retaining water, serving as a larger surface area for capture of mineral nutrients and, in some cases, provides minerals obtained from the substratum. If a cyanobacterium is present, as a primary partner or another symbiont in addition to green alga as in certain tripartite lichens, they can fix atmospheric nitrogen, complementing the activities of the green alga.
