Question

Which one of the following is not true for lichens?
A. They can be used to produce litmus.
B. Some species can be used as pollution indicators.
C. They can grow very fast.
D. Their body is composed of both algae and fungal components.

Answer 1

Hint: A lichen is a hybrid species that emerges in a mutualistic relationship from algae or cyanobacteria living within filaments of multiple species of fungi. Lichens have different features from that of their component species.

Complete answer: The symbiotic relationship between algae and fungi forms lichens and has a distinctive morphology distinct from both partners. Litmus is a blue dye obtained from different species of lichens, especially Roccella tinctoria. Lichens are particularly vulnerable to air pollution from sulphur dioxide. There could be no lichens present if the air is very badly infected with sulfur dioxide. They are susceptible to sulphur dioxide because, when exposed to high levels of sulphur dioxide emissions, their powerful absorption mechanisms result in rapid sulphur accumulation. Much less than a millimeter per year, the growth rate of lichen is very slow and this property is used to assess the age of the exposed rock.

Let us look at all the options to get the appropriate answer,
-Lichens have been used to dye woolens in the preparation of dyes such as orchil (blue dye). The Litmus used as an acid-base indicator in chemical laboratories is obtained from Roccella montagnei.
-The growth rate of lichen is very sluggish, much less than a millimeter a year, and this property is used to determine the age of the exposed rock.
-Since they don't grow in polluted areas, they act as pollution indicators.
-The symbiotic association of algae and fungi represents lichens. Algae photosynthesize while fungi consume the water and raw materials required for photosynthesis by algae.
So, choice C is the correct answer.

Note: The tendency of litmus paper to alter its colour is due to lichens being infused with litmus paper. Roccella tinctoria and Lecanora tartarea are the lichens that are used to manufacture litmus paper. One of the main producers of litmus paper products is in the Netherlands. The crushing and grinding of lichens are carried out in the method of extracting litmus solutions from lichens. To obtain the litmus solution needed, these dyes are then applied to neutral water.