A scientist is performing an investigation using biochemistry to show the evolutionary relationship between an unknown species and four known species. She compares the DNA of the same protein found in all five species.

Her data is shown in the table.

Species Sequence
unknown ACT GCA CCC
species I ACA GCA CCG
species II ACT GGT GGA
species III ACA GCA GGG
species IV ACT GCA CCG

The scientist claims that all living organisms are related by way of common descent. The comparison of which two species BEST supports her claim?

a
the unknown species and species IV
b
species II and species IV
c
the unknown species and species II
d
species I and species III

1 answer

c. the unknown species and species II

Explanation: The unknown species and species II have the most similar DNA sequence, with only one difference (ACT GCA CCC vs. ACT GGT GGA). This close similarity in their DNA sequences suggests a closer evolutionary relationship compared to the other pairs of species.