Question 1

It is estimated that 4.6% of SNPs and about 17% of all genes can be defined as pleiotropic.Which of the following might be a significant lesson for a consumer of genetic information based on this finding?

Accepted Answer

A) A test identifying a gene for a disease might actually be a test for a different disorder instead. 
B) Any variant that we gain information about might in the future be found to associate with a more stigmatizing condition. 
C) A physician might be treating the major condition but not notice even more deleterious outcomes. 
D) The classification of my genetic disorder might be incorrect. 
E) Sequencing of the candidate gene might find the wrong expected functional significance.

Question 2

Parkinson disease (PD)is a neurodegenerative disease that has been associated with a significant number of different genes,therefore showing it to be genetically heterogenic.One recent study in 278 families found evidence of two such possible loci.Evidence for linkage to chromosome 18q11 was presented by Gao et al.in 2009.Which of the following would be considered reputable evidence for this?

Accepted Answer

A) lack of quantitative difference for the occurrence of both in individuals 
B) use of persons from multiple ethnic and geographic backgrounds in the study 
C) finding the locus to be in Hardy-Weinberg equilibrium in the population 
D) finding the Lod score for association between the chromosomal location and PD to be 4.1 
E) analysis of all other possible SNPs with no such association to chromosome 18

Question 3

QTL mapping resembles linkage analysis primarily because

Accepted Answer

A) it uses statistics to analyze its data. 
B) it uses the location of a known DNA marker. 
C) it uses the three-point mapping method. 
D) the distances are reported in cM. 
E) the results are quantifiable.

Question 4

Mean platelet volume (MPV)in humans increases with heart attacks and strokes and is used to predict recurrence as well as mortality.MPV has high heritability.A recent GWA study found MPV to be associated with three SNPs on chromosomes 12,3,and 17 respectively.These three QTLs accounted for 4-5% of MPV variance.Which of the following is a reasonable explanation?

Accepted Answer

A) Other loci may also account for significant variance of MPV. 
B) These SNPs must be translocated or transposed alleles. 
C) Monitoring of these SNPs should identify those at highest risk. 
D) The three SNPs,when sequenced,should show high conservation. 
E) The three SNPs will be found in genes responsible for stroke.

Question 5

Which component of variance in a trait such as stamina in horses is the best indicator of whether the trait will respond to selection?

Accepted Answer

The answer of Which component of variance in a trait...

Question 6

An animal breeder asks your advice about which of a number of traits could most effectively be selected for in his herd.Which would you most correctly suggest?

Accepted Answer

A) a trait with high VE 
B) a high VA relative to VP 
C) a high VP relative to VG 
D) a low h² value 
E) a low selection coefficient

Question 7

For a specific desirable trait in a breed of sheep,VP is 28.6,VC is 11,and VA is 7.2.What is its broad sense heritability?

Accepted Answer

The answer of For a specific desirable trait in a...

Question 8

A recent study investigated the heritability of lean body mass (LBM)that had been previously reported as between 52 and 84% but without known specific genes.The authors used a genome-wide association (GWA)scan to identify two SNPs: rs16892496 and rs7832552 within the thyrotropin-releasing hormone receptor gene that were significantly associated with LBM.Since the gene in question involves muscle metabolism,which of the following would you predict would be associated with LBM in a given population?

Accepted Answer

A) high LBM associated with higher risk of fracture in the elderly 
B) high LBM associated with memory loss in the middle aged 
C) low LBM associated with mobility limitation in the elderly 
D) low LBM associated with the growth spurt of puberty 
E) variation of LBM for members of different geographic populations

Question 9

Calculate the narrow sense heritability (h₂)for the following data on a trait in turkeys:
VA = 11.0
VE = 94.4
VP = 114.2
VD = 13.8

Accepted Answer

The answer of Calculate the narrow sense heritability (h₂)for the...

Question 10

If a trait results from the action of several genes,it is called a ________ trait.

Accepted Answer

The answer of If a trait results from the action...

Question 11

Describe how quantitative traits can be explained in Mendelian terms.

Accepted Answer

The answer of Describe how quantitative traits can be explained...

Question 12

Given a list of the percentage of monozygotic and dizygotic twins in concordance for a selection of traits,describe how you would evaluate the relative input of environmental versus genetic factors.

Accepted Answer

The answer of Given a list of the percentage of...

Question 13

A strain of a cereal grain can be either dark tan,medium-dark tan,medium tan,light tan,or cream colored.When a dark tan and a cream plant are crossed,all F₁ are medium tan.The F₂ are distributed in a ratio of 1:4:6:4:1 from darkest to lightest.How many additive alleles are needed to produce the darkest phenotypes?

Accepted Answer

The answer of A strain of a cereal grain can...

Question 14

Many human behavioral traits have both genetic and environmental components.Bipolar disorder has long been known to be familial,and more recently a number of genes and/or SNPs have been found to be involved.What are three or more reasons that this research has been hampered?

Accepted Answer

The answer of Many human behavioral traits have both genetic...

Question 15

Which of the following best predicts the response of a trait to artificial selection?

Accepted Answer

A) VA 
B) VG 
C) H² 
D) h² 
E) standard deviation

Question 16

Of the variance and the standard deviation for a set of data about a trait,which represents the square of the difference between each of the values and the mean of the sample,divided by the degrees of freedom?

Accepted Answer

The answer of Of the variance and the standard deviation...

Question 17

Recent work in Drosophila demonstrated that the genes known as the chromatin remodeling complex co-localize at loci for hsp genes that respond to heat shock.Outline a procedure you could use to substantiate this finding.

Accepted Answer

The answer of Recent work in Drosophila demonstrated that the...

Question 18

Which will exhibit the most shared maternal effects (uterine environment,etc.): identical or fraternal twins?

Accepted Answer

The answer of Which will exhibit the most shared maternal...

Question 19

What is meant by a QTL?

Accepted Answer

The answer of What is meant by a QTL?...

Question 20

If lean body mass (LBM)and SNPs in the gene for a G-coupled receptor for a hormone secreted by the hypothalamus are associated,and the binding of this hormone is the first step in the release of thyroxin (necessary for skeletal muscle development),then increases in mutations in the hormone receptor gene would be expected to

Accepted Answer

A) increase LBM. 
B) increase secretion by the hypothalamus. 
C) decrease all thyroxin-mediated function. 
D) increase body mass index (BMI). 
E) alter the QTLs involved.

Exam 21: Genetic Analysis of Quantitative Traits