bio exam 3

Both members of a couple are carriers for an autosomal recessive disease allele. If the couple has four children, which of the following statements must be true?

50 percent of the children could be carriers of the disease.

If a plant has a total of 18 chromosomes, how many chromosomes would be present in each of its gametes?

9

Which of the following represents the genotype of an individual diploid organism?

BbCC

Which of the following differentiates meiosis from mitosis?

Mitosis is used for the repair of cells, whereas meiosis creates cells for sexual reproduction.

Which of the following accurately describes crossing over?

Paternal chromosome 7 exchanges segments of DNA with maternal chromosome 7.

If you compare a sperm cell in a human to a skin cell from the same individual, which of the following differences would you expect to find?

The sperm cell would contain only one allele for a given gene; the skin cell would contain two alleles.

The gene for a certain sex-linked trait is found only on the Y chromosome. If the male parent carries this gene, which of the following statements about the inheritance of that trait is true?

The trait will be expressed in 100 percent of the male offspring.

Autosomal dominant diseases are exhibited by anyone who carries at least one dominant allele for that gene. How is it that dominant lethal genes, such as the one that causes Huntington disease, can persist in a population?

These diseases usually take effect later in life after people have had children.

Which of the following genetic changes would NOT be passed from parent to child?

a mutation in a skin cell

A researcher is recording the process of bacteria cell division using time-lapse microscopy. Which of the following processes would she be observing?

binary fission

Feather color in a certain species of bird is controlled by a pair of alleles that exhibit codominance. If birds that are homozygous for one allele are black and birds that are homozygous for the other allele are white, then heterozygous birds would be

black and white feathers.

Which of the following is a difference between binary fission and mitosis?

breakdown of the nuclear envelope

Feather color in a certain species of bird is controlled by a pair of alleles that exhibit incomplete dominance. If birds that are homozygous for one allele are black and birds that are homozygous for the other allele are white, then heterozygous birds would be

gray

which of the following statements regarding genes is not true

in sexually reproducing species, each cell contains a single coppy of every gene

A pool of cells is treated with a chemical that halts progress through the cell cycle. In which stage of the cell cycle would most cells be found?

interphase

Mendel's laws of segregation and independent assortment both have their biological basis

meiosis.

A Punnett square is used to

predict the outcome of a genetic cross.

Most inherited human genetic disorders are inherited as ________ alleles.

recessive

In humans, the "master sex switch" that determines whether an embryo will become a male is the

sry gene

When examining the rapidly dividing cells of a fish embryo, you notice a cell that seems to contain two nuclei. The middle of the cell is pinched inward. This cell must be in ________ of mitosis.

telophase

In humans, X-linked genetic diseases

tend to be expressed more in males than in females.

If two parents are heterozygous for an autosomal recessive disease,

they are both considered genetic carriers for the disease.

In a karyotype of a male, which of the following would indicate an abnormality?

two Y chromosomes