SAT Subject Biology Practice Question 439: Answer and Explanation
9. The following data table shows the number of different amino acids in the beta hemoglobin chain of various organisms compared to the human beta chain.
|Organism||Number of different amino acids|
Human hemoglobin and gorilla hemoglobin are even
A. their hemoglobin chains differ by a single amino acid
B. human hemoglobin and gorilla hemoglobin have different functions
C. they are unable to interbreed
D. they are the result of convergent evolution
E. they are the result of parallel evolution
Correct Answer: C
C The defining factor in considering two organisms as separate species is their inability to interbreed. If humans and gorillas cannot interbreed, then they are separate species, regardless of the similarity in their hemoglobin amino acid sequence.