Lichens are widely used as environmental indicators or bio-indicators. If air is very badly polluted with sulphur dioxide there may be no lichens present, just green algae may be found. Therefore the answer is the air quality is good because of no lichens present
During anaphase, each pair of chromosomes is separated into two identical, independent chromosomes. The chromosomes are separated by a structure called the mitotic spindle. ... The separated chromosomes are then pulled by the spindle to opposite poles of the cell.
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