The greenhouse effect is due to high levels of which gas in the environment?
A. carbon dioxide
B. carbon monoxide
C. nitrogen
D. ammonia
E. oxygen
Answer: A
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All viruses have genes encoding at least:
a. their coat proteins. b. enzymes required for nucleic acid replication. c. their coat proteins and enzymes required for nucleic acid replication. d. a plasma membrane. e. their coat proteins and a plasma membrane.
This animal nurses its young, has forward
facing eyes, nails on its fingers and toes, and a moist nose. This animal is
a. a lemur. b. a tarsier. c. a bird. d. a new world monkey. e. more than one of these
Which of the following is an incorrect statement about the regulation of populations?
A) The logistic equation reflects the effect of density-dependent factors, which can ultimately stabilize populations around the carrying capacity. B) Density-independent factors have an increasingly greater effect as a population?s density increases. C) High densities in a population may cause physiological changes that inhibit reproduction. D) Because of the overlapping nature of population-regulating factors, it is often difficult to precisely determine their cause-and-effect relationships. E) The occurrence of population cycles in some populations may be the result of crowding or lag times in the response to density-dependent factors.
Why are dwarf pea plants shorter than other pea plants?
a. because they produce very little gibberellin hormone b. because they have an altered gibberellin amino acid sequence c. because the enzymes involved in gibberellin synthesis are missing d. because they cannot make any gibberellin