Deck 7: Multifactorial Traits

Question 1

Mutations and SNPs are different in that

A) SNPs are rare and typically have a large effect on a phenotype, whereas mutations are common and each contribute a small degree to a phenotype.
B) SNPs have been well-studied for a long time, but mutations have only been studied since the sequencing of the human genome.
C) mutations are rare and typically have a large effect on a phenotype, whereas SNPs are common and each may contribute a small degree to a phenotype.
D) mutations affect many DNA bases in a gene whereas SNPs affect only a single base.
E) mutations occur in autosomes and SNPs occur in the sex chromosomes.

Answer 1

C

Question 2

For a multifactorial,polygenic trait,the characteristic shape of the mathematical plot of frequency for each phenotype class is

A) linear, going up.
B) linear, going down.
C) a bell curve.
D) a square curve.
E) an ellipse.

Answer 2

C

Question 3

Polygenic traits are

A) determined by a single gene.
B) determined by more than one gene.
C) phenotypically different in different organisms.
D) associated with many symptoms.
E) determined by genes on the same chromosome.

Answer 3

B

Question 4

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

A) a criminal taking off the fingertip skin with acid.
B) rubbing the prints off by using ones hands to climb mountains.
C) a fetus touching the developing toe and finger pads to the wall of the amniotic sac.
D) cancer of the digits.
E) the fingertips rubbing away from too much computer use.

Question 5

People with very light skin have _________

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.
E) no melanocytes.

Question 6

Traits that have both inherited and environmental causes are termed

A) heritable.
B) polygenic.
C) multifactorial.
D) familial.
E) inheritable.

Question 7

Rasheed suffers terrible migraine headaches.They are likely caused by

A) at least three genes and perhaps an environmental trigger, such as a food.
B) a single gene but no environmental influences.
C) a missing chromosome.
D) poor diet and susceptibility to infection.
E) small effects of hundreds of genes.

Question 8

In a polygenic trait

A) all genes contribute equally.
B) within genes, all alleles affect the phenotype to the same degree.
C) all alleles are dominant.
D) genes contribute to varying degrees, and alleles have differing degrees of impact.
E) one gene can cancel out the effect of the environment.

Question 9

The distinction between multifactorial and polygenic traits is that

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.
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.
E) the phenotype of a multifactorial trait cannot change, and that of a polygenic trait can.

Question 10

The degree to which genes contribute to Krabbe disease compared to osteoporosis is that

A)Krabbe disease is caused by small contributions from many genes,with no environmental component.
B)Krabbe disease and osteoporosis are caused by mutations in different single genes.
C)Krabbe disease and osteoporosis are caused by a mutation in the same single gene,but it acts early in life in Krabbe disease and later in life in osteoporosis.
D)Krabbe disease is genetic and osteoporosis is caused entirely by environmental factors,such as lack of weight-bearing exercise and a diet poor in calcium and vitamin D.
E)Krabbe disease is very rare and caused by a mutation in a single gene,whereas osteoporosis is caused by several genes and environmental factors

Question 11

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

A) 4.
B) 8.
C) 20.
D) 100.
E) the entire genome.

Question 12

The term "oligogenic disorder" refers to

A) a trait or disease caused by at least two genes that contribute equally.
B) a trait or disease caused by one major gene and smaller effects of other genes.
C) a trait or disease that affects several body parts.
D) a trait or disease caused by small inputs from many genes, with no major gene.
E) a disorder that ranges greatly in severity.

Question 13

Multifactorial traits include

A) only single gene traits.
B) only polygenic traits.
C) neither single gene nor polygenic traits.
D) both single gene and polygenic traits.
E) only traits that have no genetic cause.

Question 14

The pattern of genetic transmission typical of a multifactorial trait is

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.
E) a 1:1 ratio.

Question 15

DNA sequences that contribute to polygenic traits are called

A) qualitative trait loci.
B) quantitative trait loci.
C) multifactorial trait loci.
D) single nucleotide polymorphisms.
E) polygenes.

Question 16

Mendel's laws

A) do not apply to multifactorial traits.
B) apply to multifactorial traits but may be difficult to follow because different genes contribute in different degrees to a phenotype.
C) operate in some genes that contribute to a multifactorial trait but not in others.
D) apply only to polygenic but not multifactorial traits.
E) apply only to Mendelian traits.

Question 17

Average height of college students increased throughout the 20th century because

A) more students attended college.
B) more tall students attended college.
C) more short students went into military service instead of college.
D) nutrition improved greatly in that time.
E) many mutations conferring great height occurred during that time period.

Question 18

A continuously varying trait is

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

Question 19

"Total ridge count" is

A) a multifactorial trait that considers the number of ridges in whorls, loops, or arches of the finger pad skin.
B) a single gene trait that counts the number of ridges in the small intestine.
C) the number of wives of Ridge Forrester, a character on "The Bold and the Beautiful."
D) a polygenic trait that considers the number of lines of pigment in the irises.
E) the number of kinks in a particular extended DNA sequence.

Question 20

Mutations and SNPs are similar in that

A) they can both be changes in a DNA sequence.
B) they can both be changes in an RNA sequence.
C) they both are more common in males than females.
D) both are very common.
E) both are very rare.

Question 21

Two brothers share ___ percent of their genes.

A) 10
B) 25
C) 50
D) 100
E) 0

Question 22

Jermaine is a young African-American who has symptomatic hepatitis C,a chronic liver infection.One of his roommates,Eric,also has hepatitis C,and is receiving alpha interferon. When Jermaine asks his doctor about getting the treatment,the doctor says it is only prescribed for white patients.The mistake that this doctor is making is that

A) population-based drug-ethnic/racial group associations may not apply to individuals.
B) he is a bigot.
C) hepatitis C has nothing to do with skin color.
D) he doesn't know Eric's race.
E) Jermaine might do better with delta interferon.

Question 23

A brother and sister share ___ percent of their genes.

A) 10
B) 25
C) 50
D) 100
E) 0

Question 24

The DNA of monozygotic twins is

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 identical in sequence.
C) identical in the number and distribution of copy number variants and in sequence.
D) different in the number and distribution of copy number variants and in sequence.
E) as alike as the DNA of any two full siblings.

Question 25

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

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.
E) there are too many variations to keep track of.

Question 26

Concordance refers to

A) a type of airplane.
B) percentage of monozygotic twin pairs in which both express the trait.
C) percentage of dizygotic twin pairs in which both express the trait.
D) percentage of twin pairs in which both express a trait among pairs in which at least one twin has the trait.
E) the percentage of dizygotic twin pairs in which the members look identical.

Question 27

An assumption of twin studies is that

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.
E) the twins are the same age.

Question 28

The empiric risk that the monozygotic twin of a person with cleft lip also has cleft lift is ___ times the risk to a member of the general population who has no relatives with cleft lip.

A) 4
B) 40
C) 100
D) 400
E) 0

Question 29

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

A) 10
B) 25
C) 50
D) 100
E) 0

Question 30

Heritability refers to

A) the genetic contribution to a phenotype in a population at a particular time.
B) the genetic contribution to the variability of a phenotype in a population at a particular time.
C) the number of genes contributing to a trait in a population.
D) the penetrance of the genes contributing to a trait in a population.
E) the degree to which offspring resemble parents.

Question 31

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

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 that determine body weight also affect many other phenotypes.
D) 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.
E) dominant and recessive alleles have equal impact, but dominant alleles are more common than recessive alleles.

Question 32

Empiric risk is based on ______,which is ___________.

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.
E) Mendelian inheritance; the transmission pattern of a single-gene trait.

Question 33

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

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

Question 34

Heritability of a trait can change because

A) genes mutate.
B) new SNPs form.
C) the environment can change.
D) a person can consciously change her or his heritability.
E) the heritability in a family changes with the number of children.

Question 35

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

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.
E) remains the same in a population.

Question 36

If a trait has a large inherited component,then concordance among monozygotic twins will be

A) considerably higher than that of dizygotic twins.
B) considerably lower than that of dizygotic twins.
C) about the same as that of dizygotic twins.
D) 100%.
E) 0%.

Question 37

The coefficient of relatedness indicates

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.
E) the number of alleles of the genes that are responsible for a polygenic trait.

Question 38

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

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.
E) seen in 4 out of 5 children in a family.

Question 39

The DNA of dizygotic twins is

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) different in the number and distribution of copy number variants and in sequence.
E) as alike as the DNA of any two full siblings.

Question 40

Traditional ways of evaluating multifactorial traits include

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.
E) IQ tests and assessments of athletic performance.

Question 41

Studies that implicate the environment in influencing body weight consider

A) indigenous populations where the people have lived in the same area for thousands of years and tend to all be thin.
B) populations that split, with some people remaining in the homeland and others moving to areas where their diet changes dramatically, and they gain a great deal of weight.
C) mice bred to be obese that are given different types of junk food.
D) SNPs located throughout the genome.
E) celebrities who can afford to have carefully controlled meals delivered to them every day.

Question 42

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

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.
E) GWA studies are conducted on RNA sequences.

Question 43

A gene discovery technique that looks at regions of the genome where individuals have the same alleles much more often than expected by chance,because their ancestors were blood relatives,is called

A) homozygosity mapping.
B) heterozygosity mapping.
C) the defective sibling pair approach.
D) empiric risk.
E) a genome-wide association study.

Question 44

A treatment to help a patient with a "wasting disease" such as AIDS or certain cancers might block that activity of

A) leptin.
B) neuropeptide Y.
C) ghrelin.
D) stearoyl-CoA desaturase-1.
E) insulin.

Question 45

A cohort study looks at

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.
E) empiric risk of inborn errors of metabolism.

Question 46

Genome-wide association studies have identified approximately __ regions that appear to harbor genes that control body weight.

A) 5
B) 50
C) 75
D) 200
E) 500

Question 47

Genes that help to control body weight encode the proteins

A) fibrin, fibrinogen, and hemoglobin.
B) collagen, elastin, and dystrophin.
C) estrogen, testosterone, and progesterone.
D) leptin, ghrelin, and the melanocortin-4 receptor.
E) glucosamine, chondroitin, and hyaluronic acid.