Population vs genetic variation (Cambridge A Level)

Darwin’s primary contribution to biological theory was the idea that

• an important mechanism of biological evolution is natural selection

• new alleles arise through mutation

• evolution is the change in gene frequencies over time

• genes are the units of inheritance

Which statement best represents the meaning of the term evolution:

• Changes in species toward greater complexity over time

• Changes in gene frequencies in a population over time

• The strongest individuals survive and produce the most offspring

• Changes in an individual over time in response to natural selection

Over the past several decades, natural selection has caused populations of Staphylococcus aureus (an infectious wound bacterium) to evolve resistance to most antibiotics. If antibiotic use were stopped, what would you predict would happen to these S. aureus populations?

• They will go extinct without the antibiotic.

• The frequency of resistant forms will increase in these populations.

• The populations will begin colonizing new environments.

• The frequency of nonresistant forms will increase in these populations.

Starting from a single wild canine species, humans have developed hundreds of breeds of domestic dogs. Which of the following statements is supported by this observation?

• Natural selection had not occurred very frequently in the wild dog populations.

• There was enough heritable variation in the wild canine species to create a variety of features.

• Heritable variation is low; otherwise the there would be more wild dog species.

• Most of the variation in domestic dog species is a result of variation in nutrition and training.

Differences among individual members of the same species are referred to as....

• variation

• natural selection

• fitness

• adaptation

Which of the following statements is true?

• Gene pool frequencies do not change as a result of migrations in or out of a population.

• Gene flow occurs only as a result of migrations.

• Gene flow can cause new alleles to enter a population's gene pool

• Gene does not affect population variation

Which of the following cannot cause evolution?

• genetic drift

• random mating

• gene flow

• all can cause evolution

Which of the following can introduce new alleles into a population's gene pool?

• mutation

• natural selection

• gene flow

• A and C

European and African genes entered the gene pool of Vietnam during the war in the 1960's and early 1970's primarily as a result of:

• gene flow

• migration

• natural selection

• bottleneck