Think where mitochondria are found in the greatest numbers - they are found (for example) in liver cells, kidney cells, muscle cells etc. These tissues carry out a lot of work and thus require lots of energy.
<span>Fat is a storage product that sits there until required but the thyroid does lots of work involved in metabolism and therefore requires plenty of energy.
This should help :)
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All organisms share a common ancester: humans share a common ancestor with E. coli; E. coli share a common ancestor with an oak tree; humans share a common ancestor with an oak tree.
<span>If I hypothesized the two organisms shared a recent common ancestor, they I would predict that their genomes would be highly similar. For example, their genomes would contain about the same number of bases, and the base sequences (especially of protein-coding genes) would be highly identical.</span>