A small population of Dutch settled in South
Africa in the 17th century and became known
as Afrikaners. By chance, a few Dutch settlers
carried the gene for Huntington’s disease.
Today Huntington’s disease occurs at a
relatively high frequency in this population.
This is an example of
a. the bottleneck effect.
b. the founder effect.
c. gene flow.
d. the Red Queen effect.
e. natural selection.
B
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Managers of power-line rights-of-way in the northeastern United States have discovered that dense shrub thickets, once established, can prevent establishment of forest trees. By maintaining shrubs under power lines, managers can greatly reduce the maintenance expenses (for mowing or herbicide application) normally associated with prevention of tree growth beneath power lines. Of which mechanism of succession are these managers taking advantage?
A) facilitation B) inhibition C) tolerance D) none of the above
Consider a population of crickets in which the A and a alleles at a single locus control the shape of the male and female reproductive organs
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Pseudomonas is an enteric gram negative rod.
a. true b. false