Respuesta :
Complete question:
A scientist used the amino acid sequence of cytochrome c in different species to consider evolutionary relationships.
The data below summarizes the numbers of differences in the amino acid sequences of cytochrome C found in the selected species
Species compared Number of differences
Human-chimpanzees 0
Human-Rhesus monkeys 1
Human-Horses or Donkeys 7
Human-Cow, Pigs or sheeps 7
Human-Rabbits 7
Mammals-Birds and reptiles 10-15
Mammals-Fishes 18-20
Mammals-Plants 45-48
Interpretation of the data supports which of the following statements?
(A) Rhesus monkeys are more closely related to rabbits than they are to horses.
(B) Horses and cows have identical amino acid sequences in their cytochrome c.
(C) Humans are more closely related to rabbits than they are to rhesus monkeys.
(D) Plants and animals have no similarities at all.
(E) Mammals are more closely related to reptiles than they are to fish.
Answer:
(E) Mammals are more closely related to reptiles than they are to fish.
Explanation:
So, what you need to do here is to compare the number of differences found in each comparison. Remember that this information is only regarding cytochrome C. For instance, we can see that between humans and chimpanzees, the number of differences is 0. Their amino acid sequences do not differ at all. On the contrary, the comparison of mammals and plants threw a value of 45-48 differences, meaning that they are very different from each other, almost 50%.
So, this is how you need to interpret the values of the differences in this table. Now, let us go to the options,
(A) Rhesus monkeys are more closely related to rabbits than they are to horses. Rhesus monkey was not compared to any group other than humans, so we could not say that they are more related to one animal or the other.
(B) Horses and cows have identical amino acid sequences in their cytochrome. When comparing humans with horses and then humans with cows, the number of differences was the same -7-. But these results do not indicate which are the differences. Remember that we are comparing amino acid sequences, so probably the number of differences of each group with humans is the same, but the amino acid sequences between horses and cows are not.
(C) Humans are more closely related to rabbits than they are to rhesus monkeys. Humans and rhesus monkeys express only one difference in the amino acid sequence, while humans and rabbits exhibit seven differences. This result means that humans are more closely to rhesus monkeys related than they are to rabbits.
(D) Plants and animals have no similarities at all.
As we mentioned before, plants and mammals have a difference of almost 50% in their amino-acidic sequences. It does not mean that the other 50% is also different.
(E) Mammals are more closely related to reptiles than they are to fish.
The amino acid sequence of mammals and reptiles show 10-15 differences
The amino acid sequence of mammals and fish show 18-20 differences
So yes, mammals seem to be more related to reptiles than to fishes because the number of differences with reptiles is fewer.
