Question

cytochrome c is a protein that is involved in cellular respiration in all eukaryotic organism. human cytochrome c contains 104 amino acids. the following table compares human cytochrome c with cytochrome c from a number of other organisms.

organism	number of cytochrome c amino acids that differ from human cytochrome c amino acids
chimpanzees	0
dogs	13
rattlesnakes	20
rhesus monkeys	1
yeasts	56

all of the following are valid inferences from the data above except

• all of the proteins produced by chimpanzees and humans are identical.
• chimpanzees are more closely related to humans than yeasts are.
• the cytochrome c of chimpanzees differs from that of rhesus monkeys by only one amino acid
• dogs are more closely related to humans than chickens are.

Explanation:

1. Analyze the first option: The data only shows that cytochrome c is identical between humans and chimpanzees. This doesn't mean all proteins are identical, as organisms produce many different proteins.
2. For the second option: Chimpanzees have 0 differing amino acids in cytochrome c from humans, while yeasts have 56. Fewer differences in a conserved protein like cytochrome c suggest a closer evolutionary relationship, so this inference is valid.
3. Third option: Humans and chimpanzees have 0 differences, rhesus monkeys have 1 difference from humans. So chimpanzee and rhesus monkey cytochrome c differ by 1 (0 vs 1), this is valid.
4. Fourth option: Dogs have 13 differing amino acids, chickens have 18. Fewer differences mean closer relationship, so dogs are more closely related to humans than chickens, this is valid.

Answer:

A. All of the proteins produced by chimpanzees and humans are identical.