Question

giraffes with short necks tend to be unable to access enough food, while giraffes with long necks can reach more food at the tops of trees. this causes an advantage for giraffes with long necks. how would you explain this?
a) this is an example of a stabilizing selection in which the intermediate form of a trait is advantageous compared to the extreme forms of the trait.

b) this is an example of a disruptive selection in which the population of cacti is divided and well - defined.

c) this is an example of bidirectional selection in which evolutionary pressures from multiple sources encourage an organism to adapt.

d) this is an example of directional selection in which one end of the bell curve is better adapted to its environment than the other end.
question 16 (5 points)

Explanation:

• Option A: Stabilizing selection favors intermediate traits, but here long necks (one end) are favored, so A is wrong.
• Option B: Disruptive selection favors extreme traits (splitting population), and the example is about giraffes (not cacti), so B is wrong.
• Option C: "Bidirectional selection" is not a standard type of natural selection, so C is incorrect.
• Option D: Directional selection occurs when one extreme of a trait (long necks here) is favored, shifting the population's trait distribution. Giraffes with long necks access more food, so this fits directional selection.

Answer:

D) This is an example of directional selection in which one end of the bell curve is better adapted to its environment than the other end.