When dividing cells are examined under a light microscope, chromosomes first become visible during
a. interphase.
b. the S phase.
c. prophase.
d. G1.
e. G2.
Ans: c. prophase.
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Which abiotic factor would have the most significant physiological effect on migrating salmon?
A) water solute content B) competition for resources C) ambient temperature D) human-built structural interferences
How does sickle cell anemia reduce the blood’s ability to deliver oxygen to tissues?
a. The plasma membrane is too thick to allow oxygen to diffuse into sickle-shaped red blood cells. b. Sickle-shaped red blood cells puncture normal red blood cells, causing them to rupture and lose hemoglobin. c. Deformed red blood cells clog capillaries, preventing other red blood cells from passing through. d. Sickle cells contain a mutated form of hemoglobin that binds to half as many oxygen molecules.
In some social insects, there are individuals that do not mate or may not be fertile but help look after other members of their group. Which statement regarding this situation is true?
A) Natural selection cannot act on the genes of nonreproducers since they do not leave offspring. B) The ultimate cause of this behavior is the need to keep their group safe. C) By protecting relatives, the nonreproducers increase the probability that their genes will be passed to the next generation. D) Lack of mating is an agonistic behavior.
While each of these processes are believed to have evolved prior to aerobic respiration, which one is the most critical process, without which aerobic respiration could never have developed?
A. Oxygenic photosynthesis B. Anoxygenic photosynthesis C. Lactic acid fermentation D. Alcohol fermentation