Most of the ultraviolet radiation reaching the upper atmosphere is absorbed by
A. CFCs.
B. ozone.
C. nitrogen.
D. carbon dioxide.
E. water vapor.
B. ozone.
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Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?
A) Natural selection cannot account for losses, but accounts only for new structures and functions. B) Natural selection accounts for these losses by the principle of use and disuse. C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits. D) The ancestors of these organisms experienced harmful mutations that forced them to lose these structures.
The actual exchange of gasses occurs at the site of the
a. trachea b. nasal passageway c. larynx d. alveoli
Osmoconformers are animals that __________.
a. expend considerable energy in matching concentrations of their body fluids with those of their marine environment b. rely on the digestive, respiratory, and excretory systems to remove excess salts and water from their bodies c. have an internal environment isoosmotic with their external environment d. spontaneously absorb water through the body surface and lose solutes in urine e. spontaneously lose water through body surfaces and must actively unload ions and drink water to maintain osmotic homeostasis
Tinbergen is credited with founding the field of behavioral ________, the study of how natural selection shapes behavior.
A. genetics B. demographics C. ecology D. symptomatology