In a certain species of salmon, some adult males are extremely large whereas other adult males are very small, compared to the females. There are no intermediate-sized adult males in the population. This is probably the result of
A) directional selection. B) artificial selection.
C) disruptive selection. D) stabilizing selection.
C
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Air movement to the mammalian respiratory surfaces can be reduced when smooth muscle in the walls
of the ____ contract(s).
a. epiglottis b. bronchioles c. large bronchi d. trachea e. aorta
Which hypothesis of aging involves mitochondria?
A. gene damage by free radicals B. external factors C. extrinsic factors D. whole-body process E. damage accumulation
Birds and mammals have a more active lifestyle than reptiles due to
A) insulation over their body surface. B) internal fertilization. C) a slower metabolism. D) internal fertilization and a high, constant body temperature. E) a high, constant body temperature and insulation over their body surface.
Who discovered penicillin?
A) Fleming B) Ehrlich C) Kitasato D) Pasteur E) Domagk