Question

ome mice have inherited a genetic mutation that causes them to have a band of white fur around the middle of their bodies. What is most likely true about an ancestor of these mice?
A.
A change in its food source affected only the fur around its stomach.
B.
A change in its environment changed the DNA of only part of its body.
C.
A change in its DNA resulted in a modified protein that controls fur color.
D.
A change in its fur color modified the structure of its DNA.
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Answer 1

C

A heritable band of white fur is best explained by a change (mutation) in the ancestor's DNA that altered a protein involved in pigment production or distribution (for example, enzymes like tyrosinase or genes controlling pigment cell migration). A and B invoke environmental effects that wouldn't produce a heritable, localized trait in descendants, and D reverses cause and effect (fur color doesn't change DNA).