Question 1

Due to a recessively inherited trait, some plants fail to produce chlorophyll and therefore are white rather than green. If we locate a pea plant that is heterozygous for this trait, self-pollinate it, harvest the seeds, and then plant the seeds, what are the likely phenotypes of the resulting offspring?

Accepted Answer

A)  100% green 
B)  100% white 
C)  approximately 1/2 green and 1/2 white 
D)  approximately 1/4 white and 3/4 green 
E)  approximately 1/4 green and 3/4 white

Question 2

Which of the following crosses will yield four phenotypes in a ratio of 9:3:3:1?

Accepted Answer

A)  RRYY × RRYY 
B)  RRYY × rryy 
C)  RrYy × RrYy 
D)  RrYy × rryy 
E)  rryy × rryy

Question 3

In humans, widow's peak (W) is dominant over straight hairline (w). If a heterozygous male marries a female with a straight hairline, what percent of their children can be expected to have widow's peak?

Accepted Answer

A)  0% 
B)  25% 
C)  50% 
D)  100% 
E)  The answer cannot be determined by the information given.

Question 4

The genetic makeup of an individual is also known as their

Accepted Answer

A)  phenotype. 
B)  loci. 
C)  genotype. 
D)  factors.

Question 5

Which allele combination represents a recessive monohybrid trait?

Accepted Answer

A)  aa 
B)  Aa 
C)  AA 
D)  ab 
E)  Ab

Question 6

Which genetic disorder is associated with a defect in the elastic connective tissue protein called fibrillin?

Accepted Answer

A)  Marfan syndrome 
B)  Huntington disease 
C)  sickle cell disease 
D)  phenylketonuria (PKU) 
E)  cystic fibrosis (CF)

Question 7

Which of the following produces an intermediate phenotype?

Accepted Answer

A)  codominance 
B)  sex-linked inheritance 
C)  polygenic inheritance 
D)  simple Mendelian inheritance 
E)  incomplete dominance

Question 8

Indicate the genotypic and phenotypic ratios that you could expect if an individual who is heterozygous for Huntington disease has children with a normal individual.

Accepted Answer

The answer of Indicate the genotypic and phenotypic ratios that...

Question 9

In humans, assume straight hairline is recessive to widow's peak. A woman with a straight hairline is married to a man with a widow's peak whose mother had a straight hairline. What are the chances of the couple having a child with a straight hairline?

Accepted Answer

A)  0% 
B)  25% 
C)  50% 
D)  75% 
E)  100%

Question 10

Mendel's law of segregation implies that the two members of an allele pair

Accepted Answer

A)  are distributed to separate gametes. 
B)  are distributed to the same gamete. 
C)  are assorted dependently. 
D)  are segregated pairwise. 
E)  must always code for the identical trait or feature.

Question 11

The inheritance of blood types in humans can be explained by

Accepted Answer

A)  simple Mendelian genetics (one gene pair). 
B)  linked genes. 
C)  simple dominance. 
D)  multiple alleles. 
E)  polygenic inheritance.

Question 12

What genetic disorder is associated with the lack of an enzyme necessary for the normal metabolism of the amino acid phenylalanine?

Accepted Answer

A)  phenylketonuria (PKU) 
B)  Marfan syndrome 
C)  Huntington disease 
D)  sickle cell disease 
E)  cystic fibrosis (CF)

Question 13

A woman who can roll her tongue is married to a man who cannot. Two of their four children can roll their tongues and two cannot. If T = tongue rolling and t = cannot roll tongue, then what is the genotype of the parents?

Accepted Answer

A)  woman Tt; man Tt 
B)  woman TT; man tt 
C)  woman Tt; man TT 
D)  woman Tt; man tt 
E)  woman tt; man tt

Question 14

In the human population, short fingers are dominant over long fingers. Indicate the genotypic and phenotypic ratios if a heterozygous short-fingered female reproduces with a long-fingered male.

Accepted Answer

The answer of In the human population, short fingers are...

Question 15

Unattached earlobes (EE or Ee) are dominant over attached earlobes (ee). A couple has unattached earlobes. Both notice that one of their parents on both sides have attached earlobes (ee). Therefore, they correctly assume that they are carriers for attached earlobes (Ee). If the couple proceeds to have four children, then

Accepted Answer

A)  they can be certain that three will be heterozygous and one homozygous recessive. 
B)  if the first three are heterozygous, the fourth must be homozygous recessive. 
C)  the children must repeat the grandparents' genotype (Ee). 
D)  all children must have unattached earlobes since both parents possess the dominant gene for it. 
E)  two heterozygous, one homozygous dominant, and one homozygous recessive is a likely outcome, but all genotype ratios are possible.

Question 16

A blue-eyed, left-handed woman marries a brown-eyed, right-handed man who is heterozygous for both of his traits. If blue eyes and left-handedness are recessive, how many different phenotypes are possible in their children?

Accepted Answer

A)  one 
B)  two 
C)  three 
D)  four 
E)  five

Question 17

For Mendel's law of segregation to occur, the alleles must be

Accepted Answer

A)  at different loci on the same chromosome. 
B)  at the same loci on the same chromosome. 
C)  on a nonhomologous pair of chromosomes. 
D)  on a homologous pair of chromosome at the same loci. 
E)  on different loci on different chromosomes.

Question 18

You have two true-breeding rose bushes, one with red flowers and one with white flowers. A cross between these two roses yields a bush with pink flowers. The pink flower color is an example of

Accepted Answer

A)  codominance. 
B)  incomplete dominance. 
C)  environmental effects. 
D)  polygenic inheritance. 
E)  epistatic interaction.

Question 19

Which of the following is an autosomal dominant disorder?

Accepted Answer

A)  Marfan syndrome 
B)  Tay-Sachs 
C)  sickle cell disease 
D)  cystic fibrosis (CF) 
E)  phenylketonuria (PKU)

Question 20

Hydrangeas are flowering plants with large, showy blooms. When the plant is grown in alkaline soil, the flowers are pink. When the plant is grown in acidic soil, the flowers turn blue. This change is phenotype is an example of

Accepted Answer

A)  codominance. 
B)  incomplete dominance. 
C)  environmental influence. 
D)  polygenic inheritance. 
E)  epistatic interaction.

Exam 23: Patterns of Gene Inheritance