Concept:Litmus is a natural dye that acts as an acid-base indicator, and it is derived from certain species of lichens.
Explanation:Lichens are symbiotic associations between algae and fungi that produce the pigment used to make litmus.
Specific lichen species, such as
Lecanora tartarea and
Roccella tinctoria, are the primary sources.
The extraction process involves crushing and grinding the lichen thallus to obtain the water-soluble dye.
Litmus changes color depending on the pH of the solution: blue litmus turns red in acids, and red litmus turns blue in bases.
Among the given options, only lichen is directly used for litmus production.
Protozoa are unicellular eukaryotes with a complex internal structure but do not produce litmus.
Viruses are acellular infectious agents that require living host cells and have no role in litmus synthesis.
Saccharomyces (baker's yeast) is a single-celled fungus used in baking and fermentation, not as a source of litmus.
Therefore, lichen is the correct living organism that gives litmus.
Answer:Lichen