Bio Test 1 chp 14

A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color- blind male. What is the probability that this couple's first son will be color-blind?

1/2

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt x BBtt will be expected to have black fur and long tails? (Assume the two genes are located on different chromosomes.)

1/2

Hemophilia is caused by several genetic factors; one, a recessive allele of an X- linked gene, is the subject of this problem. Assume that a man with hemophilia marries a normal woman whose father had hemophilia. What is the probability that their first son will have hemophilia?

1/2

If an organism is heterozygous for two traits that are linked, how many genotypes are possible in the gametes produced from a single germ-line cell? Assume that no crossing over occurs.

2

If the first five seeds (offspring) grown from a cross between two heterozygous parent peas with the genotype Rr are all round, what is the probability that the next offspring from these parents will be wrinkled?

25 %

Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl?

3/8

If an organism is heterozygous for two linked traits, how many genotypes are possible in the gametes produced from a single germ-line cell if a single crossing over event between the two linked genes occurred during meiosis I?

4

If an organism is heterozygous for two linked traits, how many genotypes are possible in the gametes produced from a single germ-line cell if a single crossing over event occurred during meiosis I?

4

A Punnett square is used to do which of the following? A Punnett square predicts genotypes and phenotypes of different crosses. A Punnett square allows an organism to separate alleles into different gametes. Thus, each gamete has only one allele instead of two. A Punnett square is used to describe the offspring only when heterozygous parents mate. A Punnett square depicts the formation of male and female gametes only.

A Punnett square predicts genotypes and phenotypes of different crosses.

If an individual with type O blood mates with an individual with type AB blood, what are the possible blood phenotypes of their offspring?

A and B

In Mendel's concept of particulate inheritance, what is the particle?

A gene

For an X-linked dominant trait, in a mating between an affected male and an unaffected female, all of the female offspring in the F1 generation would be affected. An affected female from the F1 generation that has children with an unaffected male would result in what percent of the offspring being affected?

About one-half of the offspring of the affected mother and unaffected father will be affected.

Which of the following statements about an X-linked dominant disease is true? >All male offspring from an unaffected female and an affected male would have the disease. >Fifty percent of the female offspring from an unaffected female and an affected male would have the disease. >All offspring from an unaffected female and an affected male would have the disease. >All female offspring from an unaffected female and an affected male would have the disease.

All female offspring from an unaffected female and an affected male would have the disease.

When homologous chromosomes cross over, what occurs?

Corresponding segments of non-sister chromatids are exchanged.

In some parts of Africa, the frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?

Darwin's explanation of natural selection

Which of the following characteristics denotes an autosomal recessive trait? It is present in 100 percent of the offspring. It is present in every generation. It often skips a generation It is expressed in 50 percent of the females.

It often skips a generation

Linked genes are inherited together unless recombination occurs. Under which of the following circumstances would linked genes be most likely to undergo recombination? Linked genes that are far apart on the chromosome Linked genes that are close together on the chromosome Linked genes on the X chromosome Linked genes that have point mutations

Linked genes that are far apart on the chromosome

If an F1 plant with the genotype RrYy self-fertilizes, what is the phenotypic ratio of the F2 generation? Keep in mind that R is the dominant allele for seed shape (round), r is the recessive allele for seed shape (wrinkled), Y is the dominant allele for seed color (yellow), and y is the recessive allele for seed color (green).

Nine round, yellow: three round, green: three wrinkled, yellow: one wrinkled, green

In snapdragon plants, T is the dominant allele for plant height (tall), t is the recessive allele for plant height (dwarf), RR flowers are red, rr flowers are white, and flower color exhibits incomplete dominance. A cross between Ttrr and TtRR results in what proportion of offspring with pink flowers on dwarf plants?

One-quarter

Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles. Only boys are affected, and they are always born to phenotypically normal parents. Due to the severity of the disease, the boys die in their teens. Is this disorder likely to be caused by a dominant or recessive allele? Is its inheritance sex-linked or autosomal?

Recessive; sex-linked

If a homozygous male for round peas (RR) is crossed with a homozygous female for wrinkled peas (rr), which of the following statements is true?

The F1 generation of this cross will produce a gamete that contains R and another that contains r.

There are many X-linked genes, some of which are associated with disease. Which of the following best describes why there are no known Y-linked traits with the exception of maleness? The Y chromosome does not have many genes and those that are present are involved in male-specific sexual development. The Y chromosome is only passed on to males and therefore only half the population has the chromosome. The Y chromosome does not have any genes. The male can only pass on dominant alleles with the Y chromosome.

The Y chromosome does not have many genes and those that are present are involved in male-specific sexual development.

Which of the following features of peas was an important aspect of Mendel's work?

The ability to control mating between pea plants

A cross between pure-breeding chicken lines with rose combs and pea combs produces offspring that all have a new phenotype, walnut comb. If two walnut comb chickens are mated, the offspring will have the following phenotypes: walnut comb, rose comb, pea comb, and a new phenotype called single comb. Which of the following statements best explains this result?

The alleles of two genes are interacting to produce the different phenotypes.

The principle of segregation says that the two alleles of any particular gene are separated into separate gamete cells during meiosis. Each gamete contains only one allele of each gene. Which of the following cases is not supported by this principle? The formation in a diploid organism of a zygote in which there are four copies of one particular gene. The formation of a sperm in which there are one-half the number of alleles of a particular gene as there were in the parent. A zygote containing two copies of a gene for a particular trait. An egg cell that contains one copy of a gene for a particular trait.

The formation in a diploid organism of a zygote in which there are four copies of one particular gene.

Which of the following statements about pure-breeding plants is true?

The offspring of two plants that are cross-pollinated will be hybrids only if, for a single gene, one parent plant exhibits the dominant trait and the other exhibit the recessive trait.

Which of the following is true about traits affected by linkage? >The traits are the result of genes that have a physical association on different chromosomes. >The traits are on the Y chromosome. >The traits are on the X chromosome. >The traits are the result of genes that have a physical association on the same chromosome.

The traits are the result of genes that have a physical association on the same chromosome.

What is the reason that closely linked genes are typically inherited together?

They are located close together on the same chromosome.

What is the frequency of each phenotype in the F2 generation of a cross between two homozygous parent peas with the genotypes RR and rr?

Three round, one wrinkled

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

Traits are inherited in discrete units and are not the results of "blending".

Tallness (T) in snapdragons is dominant to dwarfness (t), whereas red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?

TtRr, tall and pink

If an organism is heterozygous for two traits that are linked, how many genotypes are possible in the gametes produced from a single germ-line cell? Assume that no crossing over occurs.

Two

When discussing the rules of human inheritance, which of the following is a valid mode of transmission? X-linked Dominant Airborne Binary fission Sex

X-linked Dominant

A man who carries an allele of an X-linked gene will pass it on to __________.

all of his daughters

The __________ hypothesis suggested that an offspring's traits are intermediate between the mother's and father's traits.

blending inheritance

botanist studying the inheritance of flower color found that when she crossed the offspring of two pure-breeding flower lines, one purple and one white, she got the following F2 generation from planting 60 seeds: 17 plants with purple flowers 26 plants with lavender flowers 15 plants with white flowers This is an example of __________.

incomplete dominance

The law of independent assortment does not apply in the case of __________.

linked genes if crossing over does not occur between them.

Biologists refer to the observable traits of an individual, such as the shape of a pea seed or the eye color of a person, as its __________.

phenotype

A gene that influences many traits is said to be __________.

pleiotropic

Genetics is a branch of biology focused on __________.

the inheritance of traits

Red-eyed Drosophila are more common than white-eyed flies. Thus, the red-eyed Drosophila are considered the __________ of the species.

wild type