AP Bio Exam Genetics

A certain species of plant has four unlinked genetic loci, W, X, Y, and Z. Each genetic locus has one dominant allele and one recessive allele. For a plant with eh genotype WwXxYyZz what is the probably lit you that the plant will produce a gamete with a haploid genotype of Wxyz -1/16 -1/4 -1/2 -1/8

1/16

A couple has 5 children, all sons. If the woman gives birth to a sixth child what is the probability that the sixth child will be a son? -1/64 -1/5 -1/6 -5/6 -1/2

1/2

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? -38 -31 -12 -24 -It can not be determined from the information provided

12

In a particular variety of corn, kernel color is controlled by a single gene with two alleles. The dominant allele results in purple kernels, and the recessive allele results in yellow kernels. A single corncob may contain hundreds of individual kernels, each of which is the result of a separate fertilization event. Which oft he following would be the best prediction for the frequency fo yellow kernels that result from a cross between two heterozygous plants. -75% -0% -50% -25%

25%

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 the cross BbTt x Bbtt will have black fur and long tails? -3/8 -9/16 -1/2 -3/16 -1/16

3/8

How many unique gametes could be produced through independent assortment by an individual with the genotype AABbCCDdEE? -4 -8 -64 -32 -16

4

How many different genotypes are possible form the cross of AaBb x AaBb? -7 -16 -9 -4 -2

9

Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments? -helicase -DNA polymerase III -DNA polymerase I -primase -ligase

DNA polymerase I

A child is born with blood type A to a mother with blood type B. The father must have which of the following blood types? -AB, A, O -Either AB or A -Either AB or B -AB only -Either AB or O

Either AB or A

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequences of which of the following? -Gaps left at the 5' end of the lagging strand because the need for a 3' onto which nucleotides can attach -DNA polymerase that cannot replicate the leading strand template to its 5' end -The "no ends" of a circular chromosome -The evolution of telomerase enzyme -Gaps left at the 3' end of the lagging strand because of the need for a primer

Gaps left at the 5' end of the lagging strand because the need for a 3' onto which nucleotides can attach

Hydrangea macrophylla is a species of plant with blue or pink flowers. Flower color in theses plants is thought to be determined primarily by soil conditions rather than by inherited differences. Which fo the following will provide the most direct evidence that flower color is due to soil conditions? -Comparing DNA sequence information for hydrangea macrophylla to DNA sequence information for a different species of flowering plant. -Growing cuttings from teh same hydrangea macrophylla plant under controlled conditions that vary only with regard to soil pH. -Performing a genetic cross between a pink flowered plant and a blouse flowered plant and then determining the ratio of phenotypes in the offspring -Analyzing fossilized remains of an ancestral species that grew in geographic areas similar to the habitats of modern hydrangea macrophylla

Growing cuttings from teh same hydrangea macrophylla plant under controlled conditions that vary only with regard to soil pH

Which of the following best describes the parents in a test cross? -Both individuals have an unknown phenotype -One individual has the dominant phenotype and the other has the recessive phenotype -Both individuals have the recessive phenotype -Both individuals have the dominant phenotype

One individual has the dominant phenotype and the other has the recessive phenotype

A blue flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow into flowering plants. of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink-flowered offspring?

Pink flower color is a trait recessive to blue flower color.

Arctic foxes typically have a white coat in the winter. In summer, when there is no snow on the ground, the foxes typically have a darker coat. Which fo the following is most likely responsible fo rate seasonal change in coat-color? -The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat. -The diet of the foxes in summer lacks a particular nutrient, which causes the foxes to lose their white coat and grow a darker-colored coat. -Competition for mates int he's print causes each fox to increase its camouflage with the environment by producing a darker-appearing coat. -The lower temperatures in winter denature the pigment molecules in the arctic fox coat, causing the coat to become lighter in color

The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat

In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman produce a color-blind son, which of the following must be true? -Both parents carry the allele color blindness -The father carries the allele for color blindness -The father is color-blind -Neither parent carries the allele for color blindness -The mother carries the allele for color blindness

The mother carries the allele for color blindness

Two types of cholesterol transport proteins, low-density lipoproteins (LDL) and high-density hippo proteins (HDL), bind to cholesterol and carry it through the bloodstream. Familial hypercholesterolemia (FH) is characterized by high cholesterol levels in the blood, which can lead to cardiovascular disease. FH is associated with a loss-of-function mutation of a gene that encodes LDL receptors in liver cells. Individuals who are heterozygous produce lower-than normal amount of the LDL receptors, and individuals who are homozygous fo the mutant allele have no LDL receptor function. Individuals with FH can be treated with drugs that result in increased production of LDL receptors in liver cells. Which of the following best explains the observation that the drugs can effectively control blood cholesterol levels in individuals who are heterozygous but are not effective in individuals homozygous for the mutant allele. -The drugs prevent cholesterol from entering the liver cells in individuals who are heterozygous but not in individuals who are homozygous for the mutant allele. -The drugs repair the mutant allele by copying the wild-type allele -There must be at least one copy of the wild-type LDL receptor allele to produce functional LDL receptors -Cholesterol molecules primarily bind to HDL receptors in individuals with FH

There must be at least one copy of the wild-type LDL receptor allele to produce functional LDL receptors

In peas the trait for tall plants is dominating (T) and the trait for shot plants is recessive (t). The trait for yellow seed color is dominant (Y) and the trait for green seed color is receive (y). A cross between two plants results in 296 tall yellow plants and 104 tall green plants. Which of the following are most likely to be the genotypes of the parents? -TtYy x TtYy -TtYY x Ttyy -TTYY x TTYy -TtYy x TTYy

TtYy x TTYy

A genetic counselor is consulted by a young man who is worried about developing Huntington's disease, an inherited disorder caused by a dominant allele of. single gene. The young man explains that his cousin was recently diagnosed with huntington's disease, and the news has caused him to consider his own risk of developing the disorder. Which fo the following questions will best help the genetic counselor to evaluate the risk of the young man developing huntington's disease and transmitting it to his children? -Were you ever expose to substances that are suspected of being mutagens? -Were you ever in physical contact with a person diagnosed with huntington's disease? -Were you and your cousin born in the same geographical area? -Were your parents or grandparents ever diagnosed with huntington's disease

Were your parents or grandparents ever diagnosed with huntington's disease?

Which of the following can be diagnoses by examining a karoo type of an individual's white blood cells? -sickle cell anemia -cystic fibrosis -alzheimer's disease -down syndrome -duchesse muscular dystrophy

down syndrome

Coat color in mice is determined by genes on two loci. When black mice from a particular population mate, they produce offspring in the following ratios 9 black: 3 brown: 4 white. These results suggest a th white coat color is expressed as a result of -a sex-linked trait -dominance -incomplete dominance -epistasis -codominance

epistasis

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? -unwind the parental double helix -join Okazaki fragments together -stabilize the unwound parental DNA -synthesize RNA nucleotides to make a primer -catalyze the lengthening of telomeres

join Okazaki fragments together

The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because -the traits blended together during fertilization -one phenotype was completely dominant over another -each allele affected phenotypic expression -different genes interacted to produce the parental phenotype -no genes interacted to produce the parental phenotype

one phenotype was completely dominant over another

In a species that has five different alleles for a gene at a particular locus, how many different alleles may be present in the somatic cells of one diploid individual? -two -four -three -five -one

two