A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism
A) is more closely related to humans than to frogs.
B) is more closely related to frogs than to humans.
C) evolved at about the same time as frogs, which is much earlier than primates and mammals.
D) is more closely related to humans than to rats.
E) is more closely related to frogs than to humans and also evolved at about the same time as frogs, which is much earlier than primates and mammals.

Question

Quizplus · Accepted Answer

The number of amino acid differences between the new organism's hemoglobin sequence and those of other known organisms indicates the degree of evolutionary distance between them. The fact that the new organism has only five differences from a frog suggests that they are more closely related to each other than to humans, gibbons, or rats. Additionally, the relatively small number of differences between the new organism and the frog suggests that they evolved around the same time, which is much earlier than primates and mammals. Therefore, the best choice is B.

A New Organism Is Discovered in the Forests of Costa