Deck 5: The Inheritance of Complex Traits

Question 1

The heritability of a trait is the ____.

A) sum of all phenotypic variation in a population
B) average amount of genetic variation in each individual
C) proportion of phenotypic variation that is caused by different genotypes
D) absolute measurement of genotypic variation in a population
E) proportion of phenotypic variation that is caused by the environment

Answer 1

C

Question 2

The genes discovered to date account for only about 5-10% of the total variation in adult height.

Answer 2

True

Question 3

Phenotypic variation among individuals with the same genotype is known as genetic variance.

Answer 3

False

Question 4

Cleft palate is ____.

A) controlled only by genetics
B) a continuously distributed trait
C) controlled by a single gene pair
D) only transmitted from father to son
E) explained by the threshold model of complex traits

Question 5

A measured heritability of 0.7 means that 70% of the phenotypic variation observed is due to genetic differences within the population.

Question 6

During interaction between genes and environment,the phenotype ____.

A) changes the genotype
B) is expressed as discontinuous variation
C) is variable and undergoes continuous change throughout the life of the organism
D) can be quantitatively subdivided into genotypic and environmental components
E) cannot vary

Question 7

According to Wilhelm Stern's method of measurement,a ten-year-old child who is able to perform the mental tasks of a ten-year-old (but not of an eleven-year old)has an IQ of ____.

A) 80
B) 90
C) 100
D) 110
E) 120

Question 8

A trait with a heritability value of 0.75 indicates that 75% of the phenotypic variability seen in the population is caused by ____ of the population.

A) genetic differences
B) environmental differences
C) concordance
D) epigenetic effects
E) the equal contribution of the genotype and the environment

Question 9

Heritability studies cannot provide information about the number,location,or identity of genes involved in specific complex traits.

Question 10

The tall and short phenotypes in pea plants are examples of ____.

A) polygenic traits
B) continuous traits
C) multifactorial traits
D) discontinuous traits
E) gene interaction

Question 11

Continuous phenotypic variations can be explained by Mendelian inheritance.

Question 12

Most evidence indicates that skin color is controlled by ____ gene pair(s).

A) one
B) two to three
C) ten
D) five to seven
E) fifteen

Question 13

Epigenetic modifications affect the nucleotide sequence of the DNA.

Question 14

For threshold traits,the liability for a genetic disorder is distributed among individuals in a bell-shaped curve.

Question 15

The additive model for polygenic inheritance proposes that the genes controlling a trait are all on one chromosome.

Question 16

Twins are concordant for a trait when ____.

A) both twins share the trait with at least one parent
B) only identical twins have the trait
C) only fraternal twins have the trait
D) both twins have the trait
E) all of the twins' siblings have the trait

Question 17

One characteristic of continuous variation is that ____.

A) traits are usually quantified by counting
B) only a single gene pair contributes to the phenotype
C) individual genes have a large effect on the phenotype
D) phenotypic expression varies across a wide range
E) it is best analyzed in individuals rather than in populations

Question 18

Dizygotic twins originate from two separate fertilization events.

Question 19

Twin,adoption,and family studies show that obesity has a heritability that averages close to ____.

A) 0.1
B) 0.3
C) 0.5
D) 0.7
E) 0.9

Question 20

The contributions of genes and environmental factors are strictly defined during the study of complex traits.

Question 21

Complex traits are usually quantified by ____________________ rather than by ____________________.

Question 22

In obesity studies in mice,the binding of leptin activates the leptin receptor and initiates changes in ____ in the hypothalamus.

A) nucleotide sequences
B) cell membranes
C) mitochondria
D) fat storage
E) gene expression

Question 23

Using today's genetic technology,it is possible to select ____________________ for specific traits.

Question 24

Single nucleotide polymorphisms (SNPs)are organized into blocks called ____ and are inherited together.

A) haplotypes
B) chromosome assemblies
C) DNA assemblies
D) multifactorial genes
E) threshold groups

Question 25

An expanded definition of intelligence that goes beyond IQ is called ____________________ and includes verbal and spatial abilities,memory,speed of perception,and reasoning.

Question 26

Genetic testing for complex traits ____.

A) does not supply enough information to make it useful
B) reveals the phenotype of the organism
C) reveals the effects of the environment on the genome
D) reveals how many genes are involved in producing the trait
E) cannot exactly define risks

Question 27

If two genes control a trait and each has a dominant and a recessive allele,there are ____ phenotypic classes in the F2 generation.

A) three
B) five
C) nine
D) sixteen
E) thirty-two

Question 28

Along with a significant genetic component,____________________ plays a significant role in the development of spina bifida.

Question 29

Mutations of some genes for human height result in ____________________.

Question 30

Spina bifida is one of the most common and most complex birth defects involving the ____ system.

A) nervous
B) circulatory
C) respiratory
D) digestive
E) endocrine

Question 31

The concept of ____ explains why children of parents who are at the extreme ends of a normal (bell-curve)distribution for a phenotype are usually closer to the population average for the phenotype.

A) correlation coefficient
B) regression to the mean
C) multifactorial differences
D) concordance
E) epigenetics

Question 32

The ____ model of genetic analysis of complex traits assumes that each gene involved has an equal effect on the phenotype.

A) cumulative
B) additive
C) epigenetic
D) polygenic
E) phenotypic

Question 33

Genomic technology allows researchers to use ____ to survey the genome to detect associations between common variations and a specific phenotype.

A) pedigrees
B) continuous traits
C) chromosome number
D) nucleotide variations
E) RNA

Question 34

The hormone leptin is produced by ____________________ cells.

Question 35

Darker skin color is correlated with ____.

A) the northern hemisphere
B) inland regions
C) coastal regions
D) longitude
E) the intensity of UV radiation

Question 36

The correlation coefficient for unrelated people is ____________________.

Question 37

Dizygotic twins are no more or less genetically similar than are other pairs of ____________________.

Question 38

The effect of each dominant allele of a complex trait is ____________________ and _______________.

Question 39

Mendel's pea plants made good experimental subjects because they ____.

A) exhibit continuous variation
B) exhibit a variety of inheritance patterns
C) exhibit discontinuous variation and complete dominance
D) are sterile
E) have many complex traits that are easy to research

Question 40

____________________ traits are controlled by two or more genes and significant environmental interactions

Question 41

Scientists are researching how much influence ____________________ has on the differences in IQ among population groups often classified as different races.

Question 42

In humans,variations in skin color are due to differences in the amount,type,and distribution of the pigment ____________________.

Question 43

For a complex trait that is observed less frequently in a given sex in a given family,the recurrence risk for this trait is ____________________ for future children of that sex.

Question 44

If only one twin has a trait,the twins are ____________________ for that trait.

Question 45

Summarize the results of one of the first investigations of the genetics of skin color.

Question 46

Define and give examples of discontinuous and continuous phenotypic variation and explain how understanding of these two concepts resulted in important advances in human genetics.

Question 47

Figure 5-9

Refer to the figure above to explain the threshold model of complex traits.

Question 48

In twin studies,geneticists look for situations in which genetic and environmental influences are clearly ____________________.

Question 49

Describe the breeding program initiated by King Frederick William of Prussia in the early 1700s to supply tall soldiers to the Potsdam Grenadier Guard.Was it successful? Why or why not?

Question 50

One of the important assumptions made during the study of heritability in twins is that monozygotic twins share all their ____________________ and their ____________________.

Question 51

Describe the approach using genomics to identify genes that contribute to the variations in cognitive ability observed in humans.

Question 52

Summarize and give examples of the relationship between heritability and correlation coefficients and explain how each is calculated.

Question 53

Skin color in humans is a(n)____________________ trait.

Question 54

Discuss Sir Francis Galton's contribution to genetics and identify the important concept that is linked to his observations.

Question 55

Describe the relationship between single nucleotide polymorphisms and haplotypes and explain how each is used in genome-wide association studies.

Question 56

The genotype is fixed at the moment of ____________________ and,barring mutation,is unchanging.

Question 57

Summarize the results of performing genome-wide searches for genes that control obesity.

Question 58

Animal models such as the ____________________ and ____________________ are being studied to identify single genes that control aspects of learning,memory,and spatial perception.

Question 59

IQ is calculated by dividing the individual's ____________________ age by his or her ____________________ age and multiplying the quotient by 100.

Question 60

Illustrate how the five basic human eye colors can be explained by a model using two genes (A and B),each of which has two alleles (A and a,B and b).