Genetics Chapter 4

In a cross between two strains that are true breeding for purple and white flowers, the F2 phenotypic ratio would be _____ if the flower color phenotype exhibits incomplete dominance

1/4 purple; 1/4 white; and 1/2 lavender

In four-o'clock plants, red flower color is dominant to white flower color. However, heterozygous plants have a pink color. If a pink flowered plant is crossed with a white flowered plant, what will be the phenotypic ratios of their offspring?

1/2 pink, 1/2 white

Hen feathering in chickens show what type of inheritance

sex limited

Epistasis is

when one gene can mask the expression of a second gene

Sex-influenced inheritance differs from sex-limited inheritance in which of the following ways?

Expression of the phenotype occurs only in one sex in sex-limited inheritance, but not in sex-influenced inheritance

A man has a color blind mother. He marries a genotypically normal woman. What is the probability that his first son will be colorblind?

0%

What disease is though to confer heterozygote advantage with respect to tuberculosis?

Tay Sachs

Two curly-winged Drosophilia are mated and produce 973 curly and 464 wild-type offspring. What is the genetic basis for these results?

A lethal allele

Phenylketonuria in humans in an example of

an environmental-influenced trait

In human blood groups, the fact that an individual can have an AB blood type in an example of

codominance

How did Bateson and Punnett's work with comb morphology in chickens differ from the dihybrid work of Mendel?

Their F2 offspring displayed 4 unique phenotypes, not the four combinations of two phenotypes expected in a Mendelian cross

An individual with type A blood and an indivual with type B blood mate and have offspring. What blood type is not possible in their offspring?

All blood types are possible

In a dihybrid cross of two heterozygous individuals, you expect a 9:3:3:1 phenotypic ratio in the offspring, but observe a ratio of 9:7. What is the most likely explanation?

Epistatic interaction of the two genes

Sickle-cell anemia in humans is an example of

heterozygous advantage

The coat characteristics of Siamese cats and Himalayan rabbits, where proteins in the extremities function differently than in the other parts of the body is an example of

Temperature-sensitive allele

If a geneticist describes a trait as being 70% penetrant, what would they mean?

Only 70% of the individuals who carry the trait express the trait

In the ABO blood system, which is the universal receiver?

AB

Temperature-sensitive alleles are examples

conditional lethal alleles

In an epistatic interaction, the genes must be located on the same chromosome

False

At the molecular level, which of the following best explains heterozygous advantage and over dominance?

A heterozygous individual can produce more varieties of homodimer proteins
The alleles produce two different proteins with slightly different functions
The proteins produced by the alleles may provide a broader range of environmental tolerance, such as te

If an allele is dominant in one sex and recessive in another, it is an example of

sex-influenced inheritance

A woman is heterozygous for the recessive X-linked gene for Lesch-Nyhan syndrome. What proportion of her daughters will be carriers for the trait if their father is not affected?

50%

If the frequency of color blind X chromosomes is .05, what is the frequency of color blind males?

5%

Male-pattern baldness is a sex-linked trait in humans

False

For a certain trait a heterozygous individual has a selective advantage than a homozygous dominant or homozygous recessive individual. This is called___

over dominance

A heterozygote possesses a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is most likely an example of

incomplete dominance

A woman who is heterozygous for pattern baldness marries a man who is nonbald. Which of the following would be true of their offspring?

All the females would be nonbald, 1/2 of the males would be bald