IOWA STATE UNIVERSITY BIO 211-
STEWART TOP HAT QUESTIONS
EXAM 5 WITH CORRECT PASSED
ANSWERS
Which statement is the best description of "natural selection"? - correct answer ✔✔Natural
selection occurs in a population when individuals with a favorable heritable phenotype produce
more surviving offspring than individuals without this adaptation.
A population of mice has four alleles for a particular gene, with each allele occurring at a
frequency of approximately 25%. The size of this population is quickly reduced to a very small
number of individuals by a hurricane, and now only two of the original alleles remain in the
population. Assuming that individuals only survived the hurricane as a result of chance, this
change in allele number and frequency was caused by the evolutionary process known as_____.
- correct answer ✔✔Genetic Drift
A population of horned toads was split into two completely isolated populations by a mountain
that formed after a volcanic eruption. One of the two resulting populations was founded by only
a few individuals. What process (or processes) could contribute to these two populations
evolving into two distinct species after many generations? - correct answer ✔✔Mutations,
natural selection, and genetic drift all could contribute to these two populations evolving into
two distinct species.
Two populations of fox squirrels are separated by a large lake. Originally, all individuals in
population 1 had one allele for coat color (allele "A"). All individuals in population 2 had 2
different allele for coat color (allele "a"). A few individuals from population 1 successfully
migrated across the lake (by floating on a log) and joined population 2. The frequency of allele
"a" in population 2 was no longer 100% in the next generation, as some individuals now
possessed allele "A" in their genome. Based on this information alone, this is an example of
evolution by the process of ____. - correct answer ✔✔Gene Flow
STEWART TOP HAT QUESTIONS
EXAM 5 WITH CORRECT PASSED
ANSWERS
Which statement is the best description of "natural selection"? - correct answer ✔✔Natural
selection occurs in a population when individuals with a favorable heritable phenotype produce
more surviving offspring than individuals without this adaptation.
A population of mice has four alleles for a particular gene, with each allele occurring at a
frequency of approximately 25%. The size of this population is quickly reduced to a very small
number of individuals by a hurricane, and now only two of the original alleles remain in the
population. Assuming that individuals only survived the hurricane as a result of chance, this
change in allele number and frequency was caused by the evolutionary process known as_____.
- correct answer ✔✔Genetic Drift
A population of horned toads was split into two completely isolated populations by a mountain
that formed after a volcanic eruption. One of the two resulting populations was founded by only
a few individuals. What process (or processes) could contribute to these two populations
evolving into two distinct species after many generations? - correct answer ✔✔Mutations,
natural selection, and genetic drift all could contribute to these two populations evolving into
two distinct species.
Two populations of fox squirrels are separated by a large lake. Originally, all individuals in
population 1 had one allele for coat color (allele "A"). All individuals in population 2 had 2
different allele for coat color (allele "a"). A few individuals from population 1 successfully
migrated across the lake (by floating on a log) and joined population 2. The frequency of allele
"a" in population 2 was no longer 100% in the next generation, as some individuals now
possessed allele "A" in their genome. Based on this information alone, this is an example of
evolution by the process of ____. - correct answer ✔✔Gene Flow
