Most aquatic animals excrete ammonia, whereas land animals excrete urea or uric acid. What is the most likely explanation for this difference?
a. They have different diets.
b. Land animals can get the energy needed to make urea or uric acid.
c. Ammonia is very toxic, and it takes a lot of water to dilute it.
d. Land animals cannot afford the energy needed to make ammonia.
e. Fish need to get rid of ammonia, but land animals need it to live.
Answer: c. Ammonia is very toxic, and it takes a lot of water to dilute it.
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Which of the following statements is NOT true of lophophorates?
A. Their tentacles serve both in respiration and in feeding. B. They have a U-shaped digestive tract. C. They have a true coelom. D. There are three phyla of them: Phoronida, Bryozoa, Brachiopoda. E. They are parthenogenetic.
One of the main functions of the hypothalamus is to produce ____ hormones, which affect the ____
pituitary.
a. releasing; posterior b. releasing; anterior c. activating; posterior d. amplification; anterior e. suppressing; anterior
If there is no natural selection, the
A. gene frequencies in a population remain constant. B. the frequency of dominant genes increases. C. the frequency of dominant genes decreases. D. the population will become extinct.
Which of the following is not evidence for the endosymbiotic theory?
A) Chloroplasts and mitochondria contain ribosomes that resemble prokaryotic ribosomes. B) Chloroplasts and mitochondria contain their own DNA that resembles prokaryotic DNA. C) Chloroplasts and mitochondria have structures that resemble prokaryotic cell walls. D) Chloroplasts and mitochondria reproduce using binary fission, like prokaryotic cells.