Ans.
Gene are considered as fundamental units of DNA. The similarity in DNA sequences of different organisms reflect a common ancestry, which appears to be shared by all organisms present on earth.
Human DNA shows very less similarity with weeds' (plants) DNA, which is around 18%. Thus, plants show different metabolic functions from humans, such as photosynthesis.
Human DNA shows around 26% similarity with yeast (fungus) DNA, as yeasts have some housekeeping genes, same as genes present in humans. For example, genes to uptake energy from sugar breakdown.
Human DNA shows 44 % similarity with fruit fly (insect) DNA. Mammals, such as humans and insects share genes, which are responsible for their growth and structures.
Human DNA shows 92 % similarity with DNA of mouse as they both are mammals and share many common genes.
Human DNA shows 98 % similarity with DNA of chimpanzee. That is why, chimpanzees are considered as closest relative of humans.
