How is it that prezygotic isolating mechanisms can often be bypassed in human controlled breeding
experiments?
What will be an ideal response?
ANS:Prezygotic
isolating mechanisms generally arise incidentally owing to species adapting to different
environments or environmental factors. The do not evolved specifically to isolate the species, and if
forced, two species otherwise separated may produce perfectly fertile offspring. Temporal isolation,
for example, might be overcome by cold-storage of sperm or pollen for artificial insemination or
pollination later in the season. Mechanical isolation due to differences in genital structure might be
also be bypassed by artificial insemination. In orchids, species are isolated primarily by being adapted
for pollination by specific species of insect, but humans can freely cross-pollinate species within, and
in some cases, between genera, resulting in a vast array of hybrids.
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In addition to the partial pressure gradient, the other major factor that determines the rate of diffusion of gases in the
lungs is ____. a. the alveoli membrane surface area b. electrical gradients c. the thickness of the alveolar membrane d. the size of the gas molecules e. the hemoglobin concentration
After eating eggs for breakfast, you return in the evening, dunk the dirty dishes in water, and notice the yellow streaks remain "dried on." However, after soaking awhile, the complex of various egg yolk molecules easily "washes off." What has happened?
A. Heating denatured the egg protein molecules, hydrolysis reactions then formed bonds in the dried egg, and soaking in water eventually resulted in condensation reactions where water broke these bonds. B. Heating denatured the egg protein molecules, unorganized condensation reactions then formed bonds in the drying egg, and soaking in water eventually resulted in hydrolysis reactions where water broke these bonds. C. The egg monomers were fused to become one polymer, which was easily dissolved by water back into monomers. D. The presence or absence of water changes the molecules from hydrophilic to hydrophobic respectively. E. The addition of water converted organic molecules into inorganic molecules.
The control centers for breathing, blood pressure, and heart rate are located in the medulla
Indicate whether the statement is true or false
Osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the ________.
A. membranes B. compartments C. cells D. solutes