Question 1

In humans,heritability of clubfoot is 0.8.This means that expression of this condition is

Accepted Answer

A) strongly influenced by environmental factors. 
B) solely dependent on inheritance of the clubfoot gene(s). 
C) strongly dependent on inheritance of the clubfoot gene(s)but also influenced by environmental factors. 
D) inherited from an affected parent 80% of the time.

Question 2

The pattern of genetic transmission typical of a multifactorial trait is

Accepted Answer

A) discontinuous distributions such as 3:1. 
B) that of Mendelian inheritance. 
C) continuous variation of phenotypic expression. 
D) a 9:3:3:1 ratio.

Question 3

The distinction between multifactorial and polygenic traits is that

Accepted Answer

A) polygenic traits are caused by more than one gene,and multifactorial traits are caused by one or more genes as well as environmental influences. 
B) multifactorial traits are not genetic,and polygenic traits are genetic. 
C) the genetic component can be determined for polygenic traits but not for multifactorial traits. 
D) polygenic traits are caused by more than one gene,and multifactorial traits are caused by only one gene.

Question 4

The difference between cystic fibrosis and migraine is that the

Accepted Answer

A) former is caused by various environmental factors. 
B) former can be traced to a single gene. 
C) former is caused by the absence of a chromosome. 
D) latter is a Mendelian trait.

Question 5

Geneticists designate heritability as "narrow" or "broad" to account for the fact that

Accepted Answer

A) genes contribute to different degrees.Typically,recessive alleles are rare and can have a large impact and dominant alleles tend to be common with minor but additive effects. 
B) genes contribute to different degrees.Typically,dominant alleles are rare and have a small impact and recessive alleles tend to be common,each with major effects. 
C) genes contribute to different degrees.Typically,dominant alleles are rare and can have a large impact and recessive alleles tend to be common with minor but additive effects. 
D) dominant and recessive alleles have equal impact,but dominant alleles are more common than recessive alleles.

Question 6

The empiric risk to a family member of an affected individual developing a disorder caused by a multifactorial trait

Accepted Answer

A) decreases with severity of the disorder. 
B) increases with fewer affected family members. 
C) decreases in larger families. 
D) increases with increasing relatedness to affected individuals.

Question 7

The number of genes that affect skin,hair,and eye color is

Accepted Answer

A) less than 4. 
B) less than 8. 
C) more than 20,000. 
D) more than 100.

Question 8

Fingerprint pattern is inherited,but also affected by the environment.An example of how the environment naturally can alter fingerprint pattern is

Accepted Answer

A) a criminal taking off the fingertip skin with acid. 
B) a fetus touching the developing toe and finger pads to the wall of the amniotic sac. 
C) a person developing skin disorders. 
D) the fingertips rubbing away from too much computer use.

Question 9

The proportion of shared genes between a grandparent and grandchild is _____ percent.

Accepted Answer

A) 10 
B) 25 
C) 50 
D) 100

Question 10

Empiric risk is based on _____,which is the _____.

Accepted Answer

A) prevalence;rate at which a certain event occurs 
B) incidence;rate at which a certain event occurs 
C) prevalence;proportion of individuals in a population with a particular disorder at a specific time 
D) incidence;proportion of individuals in a population with a particular disorder at a specific time

Question 11

The coefficient of relatedness indicates

Accepted Answer

A) the number of relatives with a certain trait. 
B) the proportion of genes that types of relatives share. 
C) the heritability of a trait. 
D) the number of genes responsible for a polygenic trait.

Question 12

The DNA of dizygotic twins is

Accepted Answer

A) identical in the number and distribution of copy number variants,but not necessarily in sequence. 
B) different in the number and distribution of copy number variants,but not necessarily in sequence. 
C) identical in the number and distribution of copy number variants and in sequence. 
D) as alike as the DNA of any two full siblings.

Question 13

To date,the most informative studies on how and to what degree heredity and the environment influence human traits have relied on data from

Accepted Answer

A) adopted children and their biological parents. 
B) monozygotic twins reared in the same environment. 
C) monozygotic twins separated at birth. 
D) Egyptian mummies.

Question 14

An assumption of twin studies is that

Accepted Answer

A) twins are more intelligent than singletons. 
B) both twins of a pair have had similar experiences. 
C) the twins are monozygotiC. 
D) the twins are dizygotic.

Question 15

A major distinction of genome-wide association (GWA)studies,compared to the more traditional approaches of empiric risk,heritability,adoptee and twin studies,is that

Accepted Answer

A) GWA studies pepper the entire genome with markers,so that even genes that would not be expected to contribute to a phenotype can be discovered. 
B) GWA studies actually sequence entire genomes. 
C) GWA studies can be performed on healthy individuals. 
D) GWA studies consider already-known traits.

Question 16

A continuously varying trait is

Accepted Answer

A) cystic fibrosis. 
B) seed color in pea plants. 
C) extra fingers and toes. 
D) weight in humans.

Question 17

A cohort study looks at

Accepted Answer

A) a large group of people over time,keeping track of specific health conditions or measures. 
B) large groups of DZ and MZ twins. 
C) heritabilities of behavioral characteristics. 
D) patterns of copy number variants in the human genome.

Question 18

Traditional ways of evaluating multifactorial traits include

Accepted Answer

A) empiric risk and heritability. 
B) Punnett squares and pedigrees. 
C) surveys that ask people what they have been exposed to. 
D) tests for several Mendelian traits or diseases.

Question 19

People with very light skin have _____.

Accepted Answer

A) more melanocytes than people with very dark skin. 
B) fewer melanocytes than people with very dark skin. 
C) about the same number of melanocytes as people with very dark skin. 
D) red melanocytes.

Question 20

Skin color is not a good way to distinguish "races" of people because

Accepted Answer

A) it can be changed by environmental factors. 
B) it is but one of many traits that vary within and between human populations. 
C) it is not inherited. 
D) it changes over a person's lifetime.

Exam 7: Multifactorial Traits