Which of the following provides an example of epistasis?
a. The allele b17 produces a dominant phenotype, although b1 through b16 do not.
b. Recessive genotypes for each of two genes (aabb) results in an albino corn snake.
c. In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.
d. In Drosophilia (fruit flies), white eyes can be due to an X-linkd gene or to a combination of other genes.

c.

When Thomas Hunt Morgan crossed his red eyed F1 generation flies to each other, the F2 included both red and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?
a. other male-specific factors influence eye color in files.
b. other female-specific factors influence eye color in flies.
c. the gene involved is on an autosome
d. the gene involved is on the Y chromosome
e. the gene involved is on the X chromosome

e.

Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
a. PDGF
b. MPF
c. cyclin
d. protein kinase
e. Cdk

c.

Testosterone functions inside a cell by
a. becoming a second messenger that inhibits adenyl cyclase
b. binding with a receptor protein that enters the nucleus and activates specific genes
c. acting as a signal receptor that activates ion-channel proteins
d. acting as a steroid signal receptor that activates ion-channel proteins
e. coordinating a phosphorylation cascade that increases glycogen metabolism

b.

The frequency of Down syndrome in the human population is most closely correlated with which of the following?
a. average of the ages of mother and father
b. exposure of pregnant women to environmental pollutions
c. frequency of new meiosis
d. age of the mother
e. age of the father

d.

What is a genome?
a. an ordered display of chromosomes arranged from largest to smaller
b. a specific set of polypeptides within each cell
c. a specific segment of DNA within a prokaryotic chromosome
d. the complete complement of an organism's genes
e. a specialized polymer of four different kinds of monomers

d.

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%

c.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
a. estrogen has different shaped receptors for each of several cell types
b. estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding
c. estrogen has specific receptors inside several cell types, but each cell responds in the same way
d. estrogen is produced in very large concentration and therefore diffuses widely
e. estrogen is kept away from the surface of any cells not able to bind at the surface

b.

The fact that all seven of the pea plants traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following?
a. none of the traits obeyed the law of segregation
b. all of the genes controlling the traits behaved as if they were on different chromosomes
c. the formation of gametes in plants occurs by mitosis only
d. the diploid number of chromosomes in the pea plant was 7
e. all of the genes controlling the traits were located on the same chromosome

b.

What divides chromosomes into arms of varying length?
a. microtubule shortening
b. actin filaments
c. the centromere
d. the kinetochore
e. the centrosome

c.

Which of the following is an example of polygenic inheritance?
a. pink flowers in snapdragons
b. skin pigmentation in humans
c. the ABO blood groups in humans
d. White and purple flower color in peas
e. huntington's disease in humans

b.

A man with Klinefelter syndrome (47, XXY) is expected to have any of the following EXCEPT?
a. female body characteristics
b. lower sperm count
c. long limbs
d. possible breast enlargement
e. increased testosterone

e.

The centromere is a region in which?
a. new spindle microtubules form at either end
b. metaphase chromosome become aligned at the metaphase plate
c. chromatids remain attached to one another until anaphase
d. chromosome are grouped during telophase
e. the nucleus is located prior to mitosis

c.

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?
a. MPF
b. PDGF
c. cyclin
d. protein kinase
e. Cdk

e.

When a cell releases a signal molecule into the vascular systems and a number of cells distance from the source respond, this type of signaling is
a. autocrine signaling
b. endocrine signaling
c. holocrine signaling
d. paracrine signaling
e. synaptic signaling

b.

Nerve and muscle cells are in this phase
a. G0
b. M
c. G1
d. G2
e. S

a.

A woman is found to have 47 chromosomes, including 3 X chromosomes. Which of the following is her expected phenotype?
a. sterile female
b. enlarged genital structures
c. normal female
d. excessive emotional instability
e. masculine characteristics such as facial hair

c.

Which term best describes when the phenotype of the heterozygote differs from the phenotypes of both homozygotes?
a. pleiotropy
b. incomplete dominance
c. epistasis
d. multiple alleles

b.

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?
a. motor proteins of the kinetochores move the chromosomes along the spindle microtubules
b. the chromosomes are "reeled in" by the contraction of spindle microtubules
c. non-kinetochore spindle fibers serve to push chromosomes in the direction of the poles
d. both A and B
e. A B and C

a.

After telophase 1 of meiosis, the chromosomal makeup of each daughter cell is
a. haploid, and the chromosomes are each composed of two chromatids
b. diploid, and the chromosomes are each composed of two chromatids
c. diploid, and the chromosomes are each composed of a single chromatid
d. haploid, and the chromosomes are each composed of a single chromatid
e. tetraploid, and the chromosomes are each composed of two chromatids

a.

Males are more often affected by sex-linked traits than females because
a. male hormones such as testosterone often alter the effects of mutations on the X chromosome
b. X chromosomes in males generally have more mutations than X chromosomes in females
c. males are homozygous for the X chromosome
d. mutations on the Y chromosome often worsen the effects of X-linked mutations
e. female hormones such as estrogen often compensate for the effects of mutations on the X

c.

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?
a. The daughter cells have half the number of chromosomes and half the amount of DNA
b. the daughter cells have the same number of chromosomes and half the amount of DNA
c. the daughter cells have half the amount of cytoplasm and half the amount of DNA
d. the daughter cells have the same number of chromosomes and twice the amount of DNA
e. the daughter cells have the same number of chromosomes and the same amount of DNA

e.

This is the shortest part of the cell cycle
a. G1
b. G0
c. G2
d. M
e. S

d.

What is the difference between a monohybrid cross and a dihybrid cross?
a. a monohybrid cross involves a single parents, whereas a dihybrid cross involves two parents
b. a monohybrid cross produces a single progeny whereas a dihybrid cross produces two progeny
c. a monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio
d. a dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one
e. a monohybrid cros is performed for one generation, wheres a dihybrid cross is performed for two generations

d.

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, then activating relay proteins. Which type does this?
a. ligand-gated ion channels
b. steroid receptors
c. receptor tyrosine kinases
d. G protein-linked receptor

b.

Homologous chromosomes synapse and crossing over occurs
a. mitosis and meiosis ll
b. meiosis l only
c. meiosis ll only
d. mitosis only
e. mitosis and meiosis l

b.

What is a karyotype?
a. a display of every pair of homologous chromosome within a cell organized according to size and shape
b. the set of unique physical characteristics that define an individual
c. the collection of all the mutations present within the genome of an individual
d. a system of classifying cell nuclei
e. the combination of chromosomes found in a gamete

a.

It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because
a. he obtained very few F1 progeny, making statistical analysis difficult
b. the dominant phenotype were visible in the F2 generation but not in the F1
c. analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment
d. many of the F1 progeny died
e. parental traits that were not observed in the F1 reappeared in the F2

e.

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following?
a. a decrease in G-protein activity
b. an increase in receptor tyrosine kinase activity
c. lower cytoplasmic levels of cAMP
d. an increase in cytosolic calcium concentration
e. a decrease in transcriptional activity of certain genes

e.

A cell divides to produce two daughter cells that are genetically different
a. mitosis and meiosis l
b. meiosis l only
c. mitosis and meiosis ll
d. meiosis ll only
e. mitosis only

b.

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
a. serine/threonine kinases
b. tyrosine kinases
c. phosphodiesterase
d. adenyl cyclase
e. phospholipase C

e.

The general name for an enzyme that transfers phosphate groups from ATP to a protein in
a. phosphorylase
b. phosphatase
c. ATPase
d. protein kinase
e. protease

d.

Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?
a. multiple alleles
b. pleiotropy
c. incomplete dominance
d. epistasis

b.

How do cells at the completion of meiosis and compete with cells that have replicated their DNA and are just about to begin meiosis?
a. they have twice the amount of cytoplasm and half the amount of DNA
b. the have the same number of chromosomes and half the amount of DNA
c. they have half the amount of cytoplasm and twice the amount of DNA
d. they have half the number of chromosomes and half the amount of DNA
e. they have half the number of chromosomes and one-fourth the amount of DNA

e.

A Barr body is normally found in the nucleus of which kind of human cell?
a. somatic cells of a male only
b. both male and female somatic cells
c. sperm cells only
d. unfertilized egg cells only
e. somatic cells of a female only

e.

Which of the following describes the events of apoptosis?
a. its organelles become fragmented, it dies, and it is phagocytized
b. its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self digests
c. the cell dies and the presence of its fragmented contents stimulates nearby cells to divide
d. its nucleus and organelles are lysed, the cell enlarges and bursts
e. the cell dies, it is lysed, its organelles are phagoytized, the contents are recycled

b.

Which of the following is true of a species that has a chromosome number of 2n=16?
a. each cell has 8 homologous pairs
b. a gamete from this species has 4 chromosomes
c. the species is diploid with 32 chromosomes per cell
d. the species has 16 sets of chromosomes per cell following meiosis
e. during the S phase of the cell cycle there will be 32 separate chromosomes

a.

Chromatids are separated from each other
a. mitosis only
b. meiosis ll only
c. mitosis and meiosis ll
d. meiosis i only
e. mitosis and meiosis l

c.

If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis?
a. 40
b. 80
c. 30
d. 20
e. 10

e.

The toxin of Vibrio cholerae cause profuse diarrhea because it
a. modifies calmodulin and activates a cascade of protein kinases
b. modifies a G protein involved in regulation salt and water secretion
c. signals inositol triphosphate to become a second messenger for the release of calcium
d. decreases the cytosolic concentration of calcium ions, making the cells hypotonic to the intestinal cells
e. binds with adenylyl cyclase and triggers the formation of cAMP

b.

Huntington's disease is a dominant condition with late age of onset in humans. If one parents has the disease, what is the probability that his or her child will have the disease?
a. 1
b. 1/4
c. 1/2
d. 0
e. 3/4

a.