Question 1

Interpret the meaning of an H² (broad-sense heritability)value that approaches 0.0.

Accepted Answer

Almost all the phenotypic variation is determined by the environment.

Question 2

Individuals with the same genetic background and a high degree of homozygosity are said to be isogenic.Of what value are isogenic strains in genetic studies?

Accepted Answer

Because the genetic background is the same (or at least very similar),phenotypic variation must be due to nongenetic factors.

Question 3

Typically,one thinks of identical (MZ)twins being genetically identical.However,genomic differences do exist between MZ twins by epigenetic processes.What are epigenetic processes?

Accepted Answer

Epigenetic processes involve the chemical modification of DNA and associated histones.

Question 4

Quantitative inheritance involves the interaction of a number of gene loci.The pattern of genetic transmission typical of quantitative inheritance is ________.

Accepted Answer

A)  discontinuous distributions such as 3:1
B)  typical of Mendelian inheritance
C)  continuous variation of phenotypic expression
D)  a 9:3:3:1 ratio
E)  usually a pattern that clearly reflects dominance and recessiveness

Question 5

Describe the value of using twins in the study of questions relating to the relative impact of heredity versus environment.

Accepted Answer

The answer of Describe the value of using twins in...

Question 6

In the early part of the twentieth century,Nilsson-Ehle and others described experiments showing that multiple loci may be involved in the inheritance of certain traits.Such patterns are often called ________.

Accepted Answer

The answer of In the early part of the twentieth...

Question 7

Given the following numbers,calculate the mean: 10,12,14,16,18.

Accepted Answer

The answer of Given the following numbers,calculate the mean: 10,12,14,16,18....

Question 8

Assume that four polygenic gene pairs are involved in determining phenotypes of F₂.How many phenotypic classes are expected?

Accepted Answer

The answer of Assume that four polygenic gene pairs are...

Question 9

Environmental factors typically influence inheritance of ________.

Accepted Answer

A)  multiple alleles
B)  codominance
C)  trihybrid crosses
D)  polygenic traits
E)  dominantly inherited traits

Question 10

What are the name and formula for describing sample variability?

Accepted Answer

The answer of What are the name and formula for...

Question 11

Assume that you are studying a trait determined by a number of polygenes.If there are seven phenotypic categories,how many genes are probably involved?

Accepted Answer

The answer of Assume that you are studying a trait...

Question 12

What are QTLs and RFLPs?

Accepted Answer

The answer of What are QTLs and RFLPs?...

Question 13

Which formula can be used to determine the number of categories (phenotypes)possible in the F₂ results of a polygenic system?

Accepted Answer

The answer of Which formula can be used to determine...

Question 14

What is the relationship between the narrow-sense heritability (h²)index and the impact of selection?

Accepted Answer

The answer of What is the relationship between the narrow-sense...

Question 15

Heritability is a measure of the degree to which the phenotypic variation of a given trait is due to genetic factors.

Accepted Answer

A) True 
 B)False

Question 16

Traits such as height,general body structure,skin color,and some behavioral traits are probably caused primarily by genes that behave codominantly or epistatically.

Accepted Answer

A) True 
 B)False

Question 17

As used in twin studies in mammals,distinguish between the terms concordant and discordant.

Accepted Answer

The answer of As used in twin studies in mammals,distinguish...

Question 18

When a trait is polygenic but distinguished from continuous and meristic traits by having a small number of discrete classes,it is said to be a(n)________ trait.

Accepted Answer

The answer of When a trait is polygenic but distinguished...

Question 19

How many gene pairs are involved in generating a typical 1:4:6:4:1 ratio?

Accepted Answer

The answer of How many gene pairs are involved in...

Question 20

Name the three components of phenotypic variance.

Accepted Answer

The answer of Name the three components of phenotypic variance....

Exam 21: Quantitative Genetics and Multifactorial Traits