Which of the following is a true statement concerning genetic variation? March 3, 2021 by admin A) It is created by the direct action of natural selection. B) It arises in response to changes in the environment. C) It must be present in a population before natural selection can act upon the population. D) It tends to be reduced by the processes involved when diploid organisms produce gametes. E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.
The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from March 3, 2021 by admin A) frequency-dependent selection. B) evolutionary imbalance. C) heterozygote advantage. D) neutral variation. E) genetic variation being preserved by diploidy.
There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception? March 3, 2021 by admin A) Advantageous alleles do not arise on demand. B) A population’s evolution is limited by historical constraints. C) Adaptations are often compromises. D) Evolution can be influenced by environmental change. E) None