Question 1

Why are people of Ashkenazi Jewish descent more likely to be carriers of the mutations that cause Tay-Sachs and Gaucher disease?&#10;A)The environment of Eastern Europe increased their risk of developing a mutation.&#10;B)The common diet shared by these people has reduced their genetic diversity.&#10;C)Bottleneck effects have reduced the genetic diversity in this population.&#10;D)Being heterozygous for these diseases allowed them to survive cholera.

Accepted Answer

At different times in history, the Jewish population of the world was decreased deliberately, causing a population bottleneck. The holocaust of World War II is just the most recent example. With reduced numbers of people within that population, only the traits of the survivors were passed on (fewer haplotypes), limiting the genetic diversity and increasing the likelihood for expression of recessive genes.

Question 2

What factors could increase genetic diversity in a particular population?&#10;A)Genetic drift&#10;B)The population effect&#10;C)The bottleneck effect&#10;D)Increased number of haplotypes

Accepted Answer

Haplotypes are groups of genes or gene variations that are inherited together as genetic neighborhoods. As the number of these haplotypes within a given population increases, so does the genetic diversity.

Question 3

Which term refers to a random change in allele frequencies, not based on natural selection?&#10;A)Population bottleneck&#10;B)Genetic drift&#10;C)Founder effect&#10;D)Migration effect

Accepted Answer

Genetic drift is defined as a random change in allele frequencies not based on natural selection. A population bottleneck occurs when some event severely reduces the number of individuals in a population. The founder effect occurs when there is a reduction in genetic variability that comes from the separation of a population subgroup and the reproduction of that less diverse subgroup. The migration effect is not a term commonly used in population genetics.

Question 4

What criteria must a population meet in order to stay in Hardy-Weinberg equilibrium?&#10;A)Random mating, no migration, and no mutation&#10;B)Founding commonalities and no haplotype differences&#10;C)Assortative mating, migration, and frequent mutation&#10;D)Limited procreation, no diet change

Accepted Answer

The requirements for populations to stay in Hardy-Weinberg equilibrium are as follows:

Question 5

The Black Death was a pandemic spreading across Europe between 1348 and 1350. Estimates state that 30% to 60% of Europe's population died from the Black Death.If welook at Europe's population before the pandemic and compare it to the population several generations later, what are we likely to find?

A)More genetic diversity in later generations
B)Less genetic diversity in later generations
C)Less genetic diversity in earlier generations
D)The same degree of genetic diversity in later as in earlier generations

Accepted Answer

We would find less genetic diversity in later generations. The Black Death caused a population bottleneck, reducing genetic diversity in subsequent generations.

Question 6

Agroup of eight space travelers, four men and four women, settled on the planet Zebulon. Their descendants had a very high rate of the autosomal-dominant disorder moonophilia distractens. What factor could explain this phenomenon?

A)Equal exposure to an environmental mutagen
B)Hardy-Weinberg equilibrium
C)Variable expressivity
D)Founder effect

Accepted Answer

Founder effect occurs when a small group of people leave a larger population and settle somewhere else and are the main people who end up populating an area. Hardy-Weinberg equilibrium exists when allele frequencies in a population meeting certain criteria remain the same. Heterozygosity refers to the proportion of a population who are heterozygous at a particular locus. Variable expressivity refers to differences in disease severity among people who have the same genotype at the locus of interest.

Question 7

What pieces of genetic information tend to be passed down from generation to generation with the least variation?&#10;A)Mitochondrial DNA&#10;B)Nuclear DNA&#10;C)Ribosomal DNA&#10;D)Histone proteins

Accepted Answer

Mitochondrial DNA and the DNA on the Y chromosomes tend to be passed down from generation to generation with very little variation. Processes such as independent assortment of alleles during meiosis and crossing over of segments of homologous chromosomes result in increased genetic diversity.

Question 8

Which practice is most likely to result in a change in the Hardy-Weinberg equilibrium of a population or geographic area?&#10;A)Random mating from within the established population&#10;B)Geographic isolation of the established population&#10;C)Assimilation of immigrants into the existing population&#10;D)Preponderance of autosomal-dominant traits in the existing population

Accepted Answer

The first criterion for Hardy-Weinberg equilibrium is no migration (out from or into the existing population. Thus, the arrival of a group of immigrants who are assimilated into the established population represents a loss of the first criterion. As assimilation occurs, even with random mating, the new population adds to the existing gene pool. Geographic isolation of the established population contributes to Hardy-Weinberg equilibrium by reducing the chances for migration. A preponderance of autosomal-dominant traits neither contributes to nor takes away from equilibrium.

Question 9

Why is it important to consider population genetics?&#10;A)Natural selection can increase genetic diversity.&#10;B)Accurate assessment of a person's ethnicity can be identified from DNA.&#10;C)Disease risk can vary as a result of the geographic origin of one's ancestors.&#10;D)Knowing ethnicity allows accurate prediction of Huntington disease risk.

Accepted Answer

Disease risk can vary depending on the geographic origin of one's ancestors. For example, people of Ashkenazi Jewish descent are more likely to be carriers of a number of autosomal-recessive diseases. We cannot accurately identify a person's race from his or her DNA, and knowing ethnicity does not accurately predict Huntington disease risk. Natural selection decreases genetic diversity.

Question 10

What is the main purpose of population genetics?&#10;A)Determining the factors that allow allelic frequencies to change over time&#10;B)Determining the geographic origins of specific genetic-based disorders&#10;C)Assessing the effects of assortive mating on natural selection and evolution&#10;D)Assessing the differences between race and ethnicity for susceptibility and resistance to infectious diseases

Accepted Answer

The field of population genetics examines the ways in which allele frequencies change in human populations over time, including those events that keep the frequencies the same and those events that change them.

Question 11

Asmall group of people left their homeland and set sail for a tropical island. They settled there, and their descendants lived for many generations. Unfortunately,a relatively high proportion of this new population is afflicted with an autosomal-recessive disease. What would explain this?

A)They encouraged immigration of people from the mainland.
B)An unidentified environmental radiation source was present on the island.
C)One of the original group members had the gene mutation from conception.
D)Their lack of genetic diversity made them more vulnerable to new mutations.

Accepted Answer

The answer of Asmall group of people left their homeland...

Question 12

Which statement regarding genetic diversity is most accurate?&#10;A)Larger genes are more likely to display diversity than small genes.&#10;B)Genetic diversity is significant only when a population is isolated.&#10;C)Genetic disorders are more common in populations that have greater genetic diversity.&#10;D)Population bottlenecks result in loss of alleles that provide minimal selection advantage.

Accepted Answer

The answer of Which statement regarding genetic diversity is most...

Deck 20: Genetic and Genomic Variation