Question
The Aztecs were some of the first humans to slowly change teosinte,
also known as wild corn, into the current form of corn eaten today.
Which process did the Aztecs most likely use?
(A) artificial selection
(B) frequency-dependent selection
(C) natural selection
(D) sexual selection
▶️Answer/Explanation
Ans:
(A) Artificial selection occurs when humans selectively breed
organisms for desired traits. Frequency-dependent selection occurs
when the survival of an organism depends on its frequency in an
environment, so choice (B) is incorrect. Choice (C) is incorrect because
in natural selection, the environment selects for which individuals
survive and reproduce. There is no evidence for mate choice in the
question; plants usually depend on the wind or animal pollinators to
exchange gametes, so choice (D) is incorrect.
Question
The greyhound dog was originally used to hunt the fastest of game, fox
and deer. The breed dates to ancient Egypt. Early breeders of
greyhound dogs were interested in dogs with the greatest speed.
Breeders carefully selected the fastest dogs from a group of hounds.
From their offspring, the greyhound breeders again selected those dogs
that ran the fastest. By continuing selection for those dogs that ran
faster than most of the hound dog population, they gradually produced dogs that could run up to 64 km/h (40 mph). This application of
artificial selection most resembles:
(A) stabilizing selection.
(B) genetic engineering.
(C) directional selection.
(D) disruptive selection.
▶️Answer/Explanation
Ans: C
Directional selection is the type of selection, whether from the
environment or by humans (who are technically part of the environment), in
which one extreme of the phenotypic continuum is selected for (or
against).