Question

In order to compare the evolutionary relationships among species, the scientists used cytochrome-c protein. A study on cytochrome-c protein revealed one difference between humans and rhesus monkeys and ten differences between humans and kangaroos. What can be concluded from this study?

• A. Humans and kangaroos have the same proteins coded in their genes.
• B. Humans and kangaroos share a more recent ancestor than humans and rhesus monkeys.
• C. Humans are not closely related to either kangaroos or rhesus monkeys.
• D. Humans and rhesus monkeys share a more recent ancestor than human and kangaroos.
• E. Rhesus monkeys and kangaroos share a more recent ancestor than humans and rhesus monkeys.

Answer 1

The correct option is D Humans and rhesus monkeys share a more recent ancestor than human and kangaroos.

Organisms that share more amino acid sequence homology for commonly occurring proteins are supposed to be diverged from each other recently and share more recent ancestors. Since cytochrome c protein of human and rhesus monkey exhibit single difference while those of human and kangaroos exhibit ten differences, human and rhesus monkey are supposed to share more recent ancestors than human and kangaroos. Thus, the correct answer is D.