Exam 20: Genes Within Populations

You spray your kitchen with an insecticide to kill the cockroaches.A few survive and reproduce, producing a large healthy population in a few generations that all have similar genetic backgrounds.This is an example of _____

In a large population of randomly reproducing rabbits, a recessive allele r comprises 80% of the alleles for a gene.What percentage of the rabbits would you expect to have the recessive phenotype?

The presence of the disease sickle cell anemia illustrates that natural selection does not always eliminate _________ alleles.

You are studying a population of geese in which there are two color phases, brown and gray.Color in this species is controlled by a single gene, with brown dominant to gray.A random sample of 250 geese shows that 210 are brown.What percentage of the brown geese are heterozygous? (Assume that the population is in Hardy-Weinberg equilibrium.)

In some instances environmental change causes a situation where one phenotype is favored for a period of time, and then a different phenotype is favored.This oscillating selection causes

Coloration in the peppered moth (Biston betularia) is determined by a single gene with two alleles showing complete dominance.Dark moths are homozygous dominant or heterozygous for the gene, light moths are homozygous recessive.In a sample of 100 moths, you determine that 64 of the moths are dark.According to the Hardy-Weinberg rule, the expected frequency of the dominant allele is ___.

The midrange of an array of phenotypes is favored in ____.

The key point in Darwin's proposal is that the ___________ imposes the conditions that determine the direction of selection.

Cheetahs have been through a genetic bottleneck; evidence for this is that

The California populations of the Northern elephant seal are descendants from a very small population of seals that was over-hunted in the 1890s.Heterozygosity in this population would be expected to be ________ due to _______________.

During a drought on the Galapagos islands, finches with larger beaks were able to crack the large tough seeds produced by plants that survived the dry conditions.This is an example of ____.

If a population was in Hardy-Weinberg equilibrium, then ____ would occur in that population.

Based on the graph above, the color of male guppies can be seen as a balance between positive and negative selections.Bright colors are an advantage in _____, but a disadvantage in _____.

Certain small towns in the western United States have remained isolated and inbred since their settlement many years ago.Some alleles are more common in these communities as compared to the rest of the population.This effect is known as

A population of lizards lives in a rocky area next to a desert.Some lizards are light colored and blend into the sand.Others are dark and blend into the rocks.What may happen to this population of lizards over time?

"The inheritance of acquired characteristics" proposal was put forward by

The percentage of different colored water boatmen eaten by fish were graphed relative to the frequency of that color in the population.Based on the graph, a population of water boatmen would _____

Both extremes of an array of phenotypes are favored in _____ .

The frequency of a particular allele within a population can be changed, over time, by

A fur color gene in rabbits has a white dominant (W) and brown recessive allele (w).The environment changes suddenly and none of the white rabbits survive.In a population of 10,000 rabbits the initial frequency of W in the pool was 0.7.How many generations would be required to eliminate all W alleles from the population? Assume that there is no mutation and the population meets all other Hardy-Weinberg conditions.