Horses and donkeys can breed and produce sterile offspring known as mules. Horses and donkeys remain separate species because of this hybrid sterility, which is:
A. an allopatric barrier to reproduction.
B. a sympatric barrier to reproduction.
C. a prezygotic barrier to reproduction.
D. a postzygotic barrier to reproduction.
Answer: D. a postzygotic barrier to reproduction.
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Coprophagy is important for the nutritional balance of _____
A) ruminants such as cows B) insects and arthropods C) rabbits and their relatives D) squirrels and some rodents E) very large animals, such as elephants
The tapetum lucidum is a key adaptation for
A. visual function in the deep sea. B. visual function in fast moving predators. C. visual function in brightly lit shallow marine waters. D. visual function in prey species that require wide fields of vision. E. visual sensitivity in nocturnally active animals.
The difference between microevolution and macroevolution is that
A) microevolution affects bacteria and macroevolution affects larger organisms. B) microevolution happens slowly and macroevolution happens quickly. C) macroevolution happens slowly and microevolution happens quickly. D) microevolutionary changes are small, and macroevolutionary changes are large.
Some adults with attention deficit hyperactivity disorder (ADHD) have abnormally low activity of the neurotransmitter involved in pleasure, attention, memory, sleep, movement, and learning, which increases their risk of drug abuse
Which drug are they most likely to abuse? A) cocaine B) morphine C) codeine D) alcohol