Natural selection generally results in ________.
A. increased genetic variation
B. a population that is adapted to its current environment
C. an increase in the size of a population
D. a population that is better adapted to a future environment
B. a population that is adapted to its current environment
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Birds that live in marine environments, and thus lack access to fresh drinking water, _____
A) osmoregulate without using a transport epithelium for this purpose B) drink seawater and secrete excess ions through their kidneys only C) drink seawater and secrete excess ions mainly through their nasal salt glands D) have plasma that is isoosmotic to ocean water E) obtain water by eating only osmoregulating prey
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?
A) The chromosomes are "reeled in" by the contraction of spindle microtubules. B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules. C) Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles. D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. E) The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles
Using general principles to explain specific observations is called ________ reasoning.
Fill in the blank(s) with the appropriate word(s).
In individuals with normal blood sugar levels, glucose is reabsorbed into the bloodstream in the kidney by members of the GLUT transporter family, which form an aqueous pore across the membrane through which glucose can move passively. As a result, no glucose is excreted in urine. However, in people with untreated diabetes mellitus, blood sugar levels are high and glucose is often present in the urine. What can explain this occurrence?
A. High blood glucose levels reverse the concentration gradient, allowing untransported glucose to be excreted in urine. B. The GLUT transporters cannot hydrolyze ATP quickly enough for ATP to transport the extra glucose, thereby allowing untransported glucose to be excreted in urine. C. The GLUT transporters become saturated, allowing untransported glucose to be excreted in urine. D. High blood glucose levels interfere with the coupled transport of water and glucose, allowing untransported glucose to be excreted in urine.