Question

a scientist is trying to determine the relationship between clams, snails, and squid. when she generates a molecular clock, she is surprised to see that clams and squid are more closely related than clams and snails. which did the molecular clock data show?

clams and squid have been evolving separately for a longer time than clams and snails.

clams and squid have been evolving separately for a shorter time than clams and snails.

clams and snails have more in common genetically than clams and squid.

clams and snails are more similar in related structures than clams and squids.

Explanation:

A molecular clock uses genetic differences to estimate evolutionary time since divergence. Closely related species have been evolving separately for a shorter time (fewer genetic changes). Since clams and squid are more closely related, they diverged (evolved separately) later, so for a shorter time than clams and snails. Option 1 is wrong (longer time would mean less related). Option 3 is wrong (closer relation means more genetic commonality between clams - squid). Option 4 is wrong (closer relation implies more structural similarity between clams - squid).

Answer:

B. Clams and squid have been evolving separately for a shorter time than clams and snails.