What are molecular clocks? How they can be used to estimate the time of evolutionary divergences?
What will be an ideal response?
ANSWER: Because mutations that arise in noncoding regions of DNA do not affect protein structure,
they are not often eliminated by natural selection. If mutations accumulate in these
segments at a reasonably constant rate, differences in their DNA sequences can serve as a
molecular clock, indexing the time since two species diverged. Large differences imply
divergence in the distant past, whereas small differences suggest a more recent common
ancestor.
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What is the source of energy for plant roots?
What will be an ideal response?