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Subject Test Biology

Question 3 of 5

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SAT Subject Test

Which of the following most accurately reveals common ancestry among many different species of organisms?

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The amino acid sequence of their cytochrome C

Correct Answer: 
Yes

Their ability to synthesize hemoglobin

Correct Answer: 
No

The percentage of their body weight that is fat

Correct Answer: 
No

The percentage of their body surface that is used in gas exchange

Correct Answer: 
No

The mechanism of their mode of locomotion

Correct Answer: 
No

To assess common ancestry or evolutionary relationships among organisms, differences or similarities in homologous structures are studied. Differences in homologous structures reflect the accumulation of mutations over time. The only choice listed that represents a comparison of a homologous structure is choice (A): Cytochrome C is a protein that can be studied and its amino acid sequences compared. The fewer differences in the amino acid sequence, the closer the relationship.

Question Difficulty: 
easy