Unit 6 Biology multiple choice

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A man with hemophilia (a recessive, sex-linked condition) has a daughter of normal phenotype. She marries a man who is normal for the trait. What is the probability that a daughter of this mating will be a hemophiliac? That a son will be a hemophiliac? If the couple has four sons, what is the probability that all four will be born with hemophilia?

0; 1/2, 1/16

A wild-type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild type, 778; black-vestigial, 785; black-normal, 158; gray-vestigial, 162. What is the recombination frequency between these genes for body color and wing size?

17%

From the perspective of the cell receiving the message, the three stages of cell signaling are A) the paracrine, local, and synaptic stages. B) signal reception, signal transduction, and cellular response. C) signal reception, nucleus disintegration, and new cell generation. D) the alpha, beta, and gamma stages. E) signal reception, cellular response, and cell division.

B. Signal reception, signal transduction, and cellular response

An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur? A) There may be deletions later in life. B) Some abnormal gametes may be formed. C) There is an increased frequency of mutation. D) All inverted chromosomes are deleted. E) The individual is more likely to get cancer.

B. Some abnormal gametes may be formed

Which of the following occurs in meiosis but not in mitosis? A) Chromosome replication B) Synapsis of chromosomes C) Production of daughter cells D) Alignment of chromosomes at the equator E) Condensation of chromatin

B. Synapsis of chromosomes

Red-green color blindness is caused by a sex-linked recessive allele. A color-blind man marries a woman with normal vision whose father was color-blind. What is the probability that they will have a color-blind daughter? What is the probability that their first son will be color-blind? (Note the different wording in the two questions.)

1⁄4 for each daughter (1⁄2 chance that child will be female x 1⁄2 chance of a homozygous recessive genotype); 1⁄2 for first son.

Sex determination in mammals is due to the SRY region of the Y chromosome. An abnormality could allow which of the following to have a male phenotype? A) Turner syndrome, 45, X B) Translocation of SRY to an autosome of a 46, XX individual C) A person with too many X chromosomes D) A person with one normal and one shortened (deleted) X E) Down syndrome, 46, XX

B. Translocation of SRY to an autosome of a 46, XX individual

A tetrad includes which of the following sets of DNA strands? A) Two single-stranded chromosomes that have synapsed B) Two sets of sister chromatids that have synapsed C) Four sets of sister chromatids D) Four sets of unique chromosomes E) Eight sets of sister chromatids

B. Two sets of sister chromatids that have synapsed

A certain kind of snail can have a right-handed direction of shell coiling (D) or left handed coiling (d). If direction of coiling is due to a protein deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and a dd sperm-producing snail will have offspring of which genotype(s) and phenotype(s)? A) 1/2 Dd : 1/2 dd; all right coiling B) All Dd; all right coiling C) 1/2 Dd : 1/2 dd; half right and half left coiling D) All Dd; all left coiling E) All Dd; half right and half left coiling

A. 1/2 Dd: 1/2 dd; all right coiling

A phenotypically normal prospective couple seeks genetic counseling because the man knows that he has a translocation of a portion of his chromosome 4 that has been exchanged with a portion of his chromosome 12. Although he is normal because his translocation is balanced, he and his wife want to know the probability that his sperm will be abnormal. What is your prognosis regarding his sperm? A) 1/4 will be normal, 1/4 with the translocation, 1/2 with duplications and deletions. B) All will carry the same translocation as the father. C) None will carry the translocation since abnormal sperm will die. D) His sperm will be sterile and the couple might consider adoption. E) 1/2 will be normal and the rest with the fatherʹs translocation.

A. 1/4 will be normal, 1/4 with the translocation, 1/2 with duplications and deletions

If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80

A. 10

If there are 20 chromatids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80

A. 10

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female? A) 2:1 male to female B) 1:2 male to female C) 1:1 male to female D) 4:3 male to female E) 3:1 male to female

A. 2:1 male to female

Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual? A) 47, +21 B) 47, XXY C) 47, XXX D) 47, XYY E) 45, X

A. 47+21

SRY is best described in which of the following ways? A) A gene region present on the Y chromosome that triggers male development B) A gene present on the X chromosome that triggers female development C) An autosomal gene that is required for the expression of genes on the Y chromosome D) An autosomal gene that is required for the expression of genes on the X chromosome E) Required for development, and males or females lacking the gene do not survive past early childhood

A. A gene region present in the Y chromosome that triggers male development

Calico cats are female because A) a male inherits only one of the two X-linked genes controlling hair color. B) the males die during embryonic development. C) the Y chromosome has a gene blocking orange coloration. D) only females can have Barr bodies. E) multiple crossovers on the Y chromosome prevent orange pigment production.

A. A male inherits only one of the two X-linked genes controlling hair color

A human cell containing 22 autosomes and a Y chromosome is A) a sperm. B) an egg. C) a zygote. D) a somatic cell of a male. E) a somatic cell of a female.

A. A sperm

If a pair of homologous chromosomes fails to separate during anaphase of meiosis I, what will be the chromosome number of the four resulting gametes with respect to the normal haploid number (n)? A) n + 1; n + 1; n - 1; n - 1 B) n + 1; n - 1; n; n C) n+1;n-1;n-1;n-1 D) n + 1; n + 1; n; n E) n - 1; n - 1; n; n

A. A) n + 1; n + 1; n - 1; n - 1

The MPF protein complex turns itself off by A) activating a process that destroys cyclin component. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex.

A. Activating a process that destroys cyclin component

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce A) all sharp-spined progeny. B) 50% sharp-spined, 50% dull-spined progeny. C) 25% sharp-spined, 50% dull-spined, 25% spineless progeny D) all spineless progeny. E) It is impossible to determine the phenotypes of the progeny.

A. All sharp-spined progeny

Drosophila (fruit flies) usually have long wings (+) but mutations in two different genes can result in bent wings (bt) or vestigial wings (vg). If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect? A) All +bt +vg heterozygotes B) 1/2 bent and 1/2 vestigial flies C) All homozygous + flies D) 3/4 bent to 1/4 vestigial ratio E) 1/2 bent and vestigial to 1/2 normal

A. All+bt+vg heterozygous

If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? A) At most, 2 alleles for that gene B) Up to 18 chromosomes with that gene C) Up to 18 genes for that trait D) A haploid number of 9 chromosomes E) Up to, but not more than, 18 different traits

A. At most, 2 alleles for that gene

In the yeast signal transduction pathway, after both types of mating cells have released the mating factors and the factors have bound to specific receptors on the correct cells, A) binding induces changes in the cells that lead to cell fusion. B) the cells then produce the a factor and the α factor. C) one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. D) the cell membranes fall apart, releasing the mating factors that lead to new yeast cells. E) a growth factor is secreted that stimulates mitosis in both cells.

A. Binding induces changes in the cells that lead to cell fusion

When a disease is said to have a multifactorial basis, it means that A) both genetic and environmental factors contribute to the disease. B) it is caused by a gene with a large number of alleles. C) it affects a large number of people. D) it has many different symptoms. E) it tends to skip a generation.

A. Both genetic and environmental factors contribute to the disease

In general, a signal transmitted via phosphorylation of a series of proteins A) brings a conformational change to each protein. B) requires binding of a hormone to a cytosol receptor. C) cannot occur in yeasts because they lack protein phosphatases. D) requires phosphorylase activity. E) allows target cells to change their shape and therefore their activity.

A. Brings a conformational change to each protein

How does the sexual life cycle increase the genetic variation in a species? A) By allowing independent assortment of chromosomes B) By allowing fertilization C) By increasing gene stability D) By conserving chromosomal gene order E) By decreasing mutation frequency

A. By allowing independent assortment of chromosomes

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in A) cells with more than one nucleus. B) cells that are unusually small. C) cells lacking nuclei. D) destruction of chromosomes. E) cell cycles lacking an S phase.

A. Cells with more than one nucleus

The activation of receptor tyrosine kinases is characterized by A) dimerization and phosphorylation. B) IP3 binding. C) a phosphorylation cascade. D) GTP hydrolysis. E) channel protein shape change.

A. Dimerization and phosphorylation

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A) disruption of mitotic spindle formation. B) inhibition of regulatory protein phosphorylation. C) suppression of cyclin production. D) myosin denaturation and inhibition of cleavage furrow formation. E) inhibition of DNA synthesis.

A. Disruption of mitotic spindle formation

A fruit fly that is true-breeding for gray body, vestigial wings (b+ b+ vg vg) is mated with one that is true-breeding for black body, normal wings (b b vg+ vg+). A) Draw the chromosomes for each P generation fly, showing the position of each allele. B) Draw the chromosomes and label the alleles for an F 1 fly. C) Suppose an F1 female is testcrossed. Draw the chromosomes of the resulting offspring in a Punnett square like the one at the bottom of Fig. 15.10 in your textbook. D) Knowing that the distance between these two genes is 17 map units, predict the phenotypic ratios of these offspring.

A. Draw the chromosomes for each P generation fly, showing the position of each allele

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. If both children are of blood group MM, which of the following is possible? A) Each parent is either M or MN. B) Each parent must be type M. C) Both children are heterozygous for this gene. D) Neither parent can have the N allele. E) The MN blood group is recessive to the ABO blood group.

A. Each parent is either M or MN

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following? A) Environmental factors such as soil pH B) The allele for blue hydrangea being completely dominant C) The alleles being codominant D) The fact that a mutation has occurred E) Acknowledging that multiple alleles are involved

A. Environmental factors such as soil pH

The human genome is minimally contained in which of the following? A) Every human cell B) Each human chromosome C) The entire DNA of a single human D) The entire human population E) Each human gene

A. Every human cell

Cells that are in a nondividing state are in which phase? A) G0 B) G2 C) G1 D) S E) M

A. G0

Nerve and muscle cells are in this phase: A) G0 B) G1 C) S D) G2 E) M

A. G0

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in A) G1 B) G2. C) prophase. D) metaphase. E) anaphase.

A. G1

A sexually reproducing animal has two unlinked genes, one for head shape ( H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? A) HT B) Hh C) HhTt D) T E) tt

A. HT

What is the chromosomal system of sex determination in most species of ants and bees? A) Haploid-diploid B) X-0 C) X-X D) X-Y E) Z-W

A. Haploid-diploid

Which of the following happens at the conclusion of meiosis I? A) Homologous chromosomes are separated. B) The chromosome number per cell is conserved. C) Sister chromatids are separated. D) Four daughter cells are formed. E) The sperm cells elongate to form a head and a tail end.

A. Homologous chromosomes are separated

One inhibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vessels and increase of blood in the penis, facilitating erection. cGMP is inhibited, therefore the signal is prolonged. The original signal that is now inhibited would have A) hydrolyzed cGMP to GMP. B) hydrolyzed GTP to GDP. C) phosphorylated GDP. D) dephosphorylated cGMP. E) removed GMP from the cell.

A. Hydrolyzed cGMP to GMP

I. Prophase II. Metaphase I III. Anaphase I IV. Telophase I IV. Prophase II VI. Metaphase II VII. Anaphase II VIII. Telophase II Synapsis of homologous pairs occurs; crossing over may occur. A) I B) II C) IV D) VI E) VII

A. I

Which of the following terms best describes when the phenotype of the heterozygote differs from the phenotypes of both homozygotes? A) Incomplete dominance B) Multiple alleles C) Pleiotropy D) Epistasis

A. Incomplete dominance

How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? A) The two genes are linked. B) The two genes are linked but on different chromosomes. C) Recombination did not occur in the cell during meiosis. D) The testcross was improperly performed. E) Both of the characters are controlled by more than one gene.

A. The two genes are linked

What is the reason that linked genes are inherited together? A) They are located close together on the same chromosome. B) The number of genes in a cell is greater than the number of chromosomes. C) Chromosomes are unbreakable. D) Alleles are paired together during meiosis. E) Genes align that way during metaphase I of meiosis.

A. They are located close together on the same chromosome

A cell that has 2n + 1 chromosomes is A) trisomic. B) monosomic. C) euploid. D) polyploid. E) triploid.

A. Trisomic

Protein phosphorylation is commonly involved with all of the following except A) regulation of transcription by extracellular signal molecules. B) enzyme activation. C) activation of G protein-coupled receptors. D) activation of receptor tyrosine kinases. E) activation of protein kinase molecules.

C. Activation of G protein-coupled receptors

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of A) phosphorylated proteins. B) GTP. C) cAMP. D) adenylyl cyclase. E) activated G proteins.

C. Adenylyl cyclase

The frequency of Down syndrome in the human population is most closely correlated with which of the following? A) Frequency of new meiosis B) Average of the ages of mother and father C) Age of the mother D) Age of the father E) Exposure of pregnant women to environmental pollutants

C. Age of the mother

Mendelʹs second law of independent assortment has its basis in which of the following events of meiosis I? A) Synapsis of homologous chromosomes B) Crossing over C) Alignment of tetrads at the equator D) Separation of homologs at anaphase E) Separation of cells at telophase

C. Alignment of tetrads at the equator

An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient? A) CVS B) Ultrasound imaging C) Amniocentesis D) Fetoscopy E) X-ray

C. Amniocentesis

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The manʹs father was six feet tall, and both the womanʹs parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their sons would be color-blind and of normal height? A) All B) None C) Half D) One out of four E) Three out of four

C. Half

If a human interphase nucleus contains three Barr bodies, it can be assumed that the person A) has hemophilia. B) is a male. C) has four X chromosomes. D) has Turner syndrome. E) has Down syndrome.

C. Has four X chromosomes

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores A) I, IV, and V B) I, II, and IV C) II, III, and IV D) II, IV, and V E) All of the above

C. II, III, and IV

A Barr body is normally found in the nucleus of which kind of human cell? A) Unfertilized egg cells only B) Sperm cells only C) Somatic cells of a female only D) Somatic cells of a male only E) Both male and female somatic cells

C. Somatic cells of a female only

Which of the following is a map of a chromosome that includes the positions of genes relative to visible chromosomal features, such as stained bands? A) Linkage map B) Physical map C) Recombination map D) Cytogenetic map E) Banded map

D. Cytogenetic map

A nonreciprocal crossover causes which of the following products? A) Deletion only B) Duplication only C) Nondisjunction D) Deletion and duplication E) Duplication and nondisjunction

D. Deletion and duplication

Chemical signal pathways A) operate in animals, but not in plants. B) are absent in bacteria, but are plentiful in yeast. C) involve the release of hormones into the blood. D) often involve the binding of signal molecules to a protein on the surface of a target cell. E) use hydrophilic molecules to activate enzymes.

D. Often involve the binding of a signal molecule to a protein in the surface of a target cell

Which of the following statements about genes is incorrect? A) Genes correspond to segments of DNA. B) Many genes contain the information needed for cells to synthesize enzymes and other proteins. C) During fertilization, both the sperm and the ovum contribute genes to the resulting fertilized egg. D) One gene only is used in a specific cell type. E) Genetic differences can result from changes in the DNA called mutations.

D. One gene only is used in a specific cell type

A couple has a child with Down syndrome when the mother is 39 years old at the time of delivery. Which is the most probable cause? A) The woman inherited this tendency from her parents. B) One member of the couple carried a translocation. C) One member of the couple underwent nondisjunction in somatic cell production. D) One member of the couple underwent nondisjunction in gamete production.

D. One member of the couple underwent nondisjunction in gamete production

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A—B, 8 map units; A—C, 28 map units; A—D, 25 map units; B —C, 20 map units; B—D, 33 map units.

D—A—B—C

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

E. Cdk

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B? A) spindle formation B) spindle attachment to kinetochores C) DNA synthesis D) cell elongation during anaphase E) cleavage furrow formation

E. Cleavage furrow formation

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called A) ATPases. B) kinetochores. C) centrioles. D) proton pumps. E) cyclins.

E. Cyclin

The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following? A) Mitosis in her ovary B) Metaphase I of one meiotic event C) Telophase II of one meiotic event D) Telophase I of one meiotic event E) Either anaphase I or II

E. Either anaphase I or II

Sutherland discovered that epinephrine A) signals bypass the plasma membrane of cells. B) lowers blood glucose by binding to liver cells. C) interacts with insulin inside muscle cells. D) interacts directly with glycogen phosphorylase. E) elevates the cytosolic concentration of cyclic AMP.

E. Elevates the cytosolic concentration of cyclic AMP

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. These results indicate which of the following? A) Brown is dominant to black. B) Black is dominant to brown and to yellow. C) Yellow is dominant to black. D) There is incomplete dominance. E) Epistasis is involved.

E. Epistasis is involved

During which phases of mitosis are chromosomes composed of two chromatids? A) from interphase through anaphase B) from G1 of interphase through metaphase C) from metaphase through telophase D) from anaphase through telophase E) from G2 of interphase through metaphase

E. From G2 of interphase through metaphase

Mendel was able to draw his ideas of segregation and independent assortment because of the influence of which of the following? A) His reading and discussion of Darwinʹs Origin of Species B) The understanding of particulate inheritance he learned from renowned scientists of his time C) His discussions of heredity with his colleagues at major universities D) His reading of the scientific literature current in the field E) His experiments with the breeding of plants such as peas

E. His experiments with the breeding of plants such as peas

A 0.1% frequency of recombination is observed A) only in sex chromosomes. B) only on genetic maps of viral chromosomes. C) on unlinked chromosomes. D) in any two genes on different chromosomes. E) in genes located very close to one another on the same chromosome.

E. In genes located very close to one another on the same chromosome

Which of the following describes cell communication systems? A) Cell signaling evolved more recently than systems such as the immune system of vertebrates. B) Communicating cells are usually close together. C) Most signal receptors are bound to the outer membrane of the nuclear envelope. D) Lipid phosphorylation is a major mechanism of signal transduction. E) In response to a signal, the cell may alter activities by changes in cytosol activity or in transcription of RNA.

E. In response to a signal, the cell may alter activities by changes in cytosol activity or in transcription of RNA

Which of the following about the law of segregation is false? A) It states that each of two alleles for a given trait segregate into different gametes. B) It can be explained by the segregation of homologous chromosomes during meiosis. C) It can account for the 3:1 ratio seen in the F2 generation of Mendelʹs crosses. D) It can be used to predict the likelihood of transmission of certain genetic diseases within families. E) It is a method that can be used to determine the number of chromosomes in a plant.

E. It is a method that can be used to determine the number of chromosomes in a plant

E. It's a method that can be used to determine the number of chromosomes in a plant

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? A) It must be human. B) It must be a primate. C) It must be an animal. D) It must be sexually reproducing. E) Its gametes must have 23 chromosomes.

E. It's gametes must have 23 chromosomes

At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype? A) Early prophase B) Late telophase C) Anaphase D) Late anaphase or early telophase E) Late prophase or metaphase

E. Late prophase or metaphase

The cyclin component of MPF is destroyed toward the end of this phase: A) G0 B) G1 C) S D) G2 E) M

E. M

This is the shortest part of the cell cycle: A) G0 B) G1 C) S D) G2 E) M

E. M

Down syndrome has a frequency in the U.S. population of ~ 1/700 live births. In which of the following groups would you expect this to be significantly higher? A) People in Latin or South America B) The Inuit and other peoples in very cold habitats C) People living in equatorial areas of the world D) Very small population groups E) No groups have such higher frequency

E. No groups have such higher frequency

Which term describes centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

E. Prophase

The frequency of crossing over between any two linked genes will be which of the following? A) Higher if they are recessive B) Dependent on how many alleles there are C) Determined by their relative dominance D) The same as if they were not linked E) Proportional to the distance between them

E. Proportional to the distance between them

Assume that genes A and B are linked and are 50 map units apart. An animal heterozygous at both loci is crossed with one that is homozygous recessive at both loci. What percentage of the offspring will show phenotypes resulting from crossovers? If you did not know that genes A and B were linked, how would you interpret the results of this cross?

Fifty percent of the offspring would show phenotypes that resulted from crossovers. These results would be the same as those from a cross where A and B were not linked. Further crosses involving other genes on the same chromosome would reveal the linkage and map distances.

A man with type A blood marries a woman with type B blood. Their child has type O blood. What are the genotypes of these individuals? What other genotypes, and in what frequencies, would you expect in offspring from this marriage?

Man IAi; woman IBi; child ii. Other genotypes for children are 1⁄4 IAIB, 1⁄4 IAi, 1⁄4 IBi.

DNA is replicated at this time of the cell cycle: A) G0 B) G1 C) S D) G2 E) M

C. S

Imagine that a newly discovered, recessively inherited disease is expressed only in individuals with type O blood, although the disease and blood group are independently inherited. A normal man with type A blood and a normal woman with type B blood have already had one child with the disease. The woman is now pregnant for a second time. What is the probability that the second child will also have the disease? Assume that both parents are heterozygous for the gene that causes the disease.

1/16

A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Extra digits is a dominant trait. What fraction of this coupleʹs children would be expected to have extra digits?

1/2

Imagine that you are a genetic counselor, and a couple planning to start a family comes to you for information. Charles was married once before, and he and his first wife had a child with cystic fibrosis. The brother of his current wife, Elaine, died of cystic fibrosis. What is the probability that Charles and Elaine will have a baby with cystic fibrosis? (Neither Charles nor Elaine has cystic fibrosis.)

1/6

Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to reveal sickle-cell trait. Based on this incomplete information, calculate the probability that if this couple has a child, the child will have sickle-cell disease.

1/9

In another cross, a wild-type fruit fly (heterozygous for gray body color and red eyes) is mated with a black fruit fly with purple eyes. The offspring are as follows: wild type, 721; black-purple, 751; gray-purple, 49; black-red, 45. What is the recombination frequency between these genes for body color and eye color? Using information from problem 4, what fruit flies (genotypes and phenotypes) would you mate to determine the sequence of the body-color, wing-size, and eye-color genes on the chromosome?

6%. Wild type (heterozygous for normal wings and red eyes) × recessive homozygote with vestigial wings and purple eyes

n mice, black color (B) is dominant to white (b). At a different locus, a dominant allele (A) produces a band of yellow just below the tip of each hair in mice with black fur. This gives a frosted appearance known as agouti. Expression of the recessive allele ( a) results in a solid coat color. If mice that are heterozygous at both loci are crossed, what is the expected phenotypic ratio of their offspring?

9 B_A_ (agouti) : 3 B_aa (black) : 3 bbA_ (white) : 1 bbaa (white). Overall, 9 agouti : 3 black : 4 white.

Fibroblasts have receptors for this substance on their plasma membranes: A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

A PDGF

What is the probability that each of the following pairs of parents will produce the indicated offspring? (Assume independent assortment of all gene pairs.) A) AABBCC × aabbcc AaBbCc B) AABbCc × AaBbCc AAbbCC C) AaBbCc × AaBbCc AaBbCc D) aaBbCC × AABbcc AaBbCc

A) 1, B) 1⁄32, C) 1⁄8, D) 1⁄2

The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of these four genes, what are the probabilities that F 2 offspring will have the following genotypes? A) aabbccdd B) AaBbCcDd C) AABBCCDD D) AaBBccDd E) AaBBCCdd

A) 1⁄256, B) 1⁄16, C) 1⁄256, D) 1⁄64, E) 1/128

In sesame plants, the one-pod condition (P) is dominant to the three-pod condition (p), and normal leaf (L) is dominant to wrinkled leaf (l). Pod type and leaf type are inherited independently. Determine the genotypes for the two parents for all possible matings producing the following offspring: A) 318 one-pod, normal leaf and 98 one-pod, wrinkled leaf B) 323 three-pod, normal leaf and 106 three-pod, wrinkled leaf C) 401 one-pod, normal leaf D) 150 one-pod, normal leaf, 147 one-pod, wrinkled leaf, 51 three-pod, normal leaf, and 48 three-pod, wrinkled leaf E) 223 one-pod, normal leaf, 72 one-pod, wrinkled leaf, 76 three-pod, normal leaf, and 27 three-pod, wrinkled leaf

A) PPLl × PPLl, PPLl × PpLl, or PPLl × ppLl. B) ppLl × ppLl. C) PPLL × any of the 9 possible genotypes or PPll × ppLL. D) PpLl × Ppll. E) PpLl × PpLl.

Paracrine signaling A) involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid. B) requires nerve cells to release a neurotransmitter into the synapse. C) occurs only in paracrine yeast cells. D) has been found in plants but not animals. E) involves mating factors attaching to target cells and causing production of new paracrine cells.

A. Involves secreting cells acting on nearby target cells by discharging a local regulator into the extra cellular fluid

Human caspases can be activated by A) irreparable DNA damage or protein misfolding. B) infrequency of cell division. C) high concentrations of vitamin C. D) a death-signaling ligand being removed from its receptor. E) electron transport.

A. Irreparable DNA damage or protein misfolding

Which of the following statements describes genomic imprinting? A) It explains cases in which the gender of the parent from whom an allele is inherited affects the expression of that allele. B) It is greatest in females because of the larger maternal contribution of cytoplasm. C) It may explain the transmission of Duchenne muscular dystrophy. D) It involves an irreversible alteration in the DNA sequence of imprinted genes.

A. It explains cases in which the gender of the parent from whom an allele is inherited affects the expression of that allele

What would be true for the signaling system in an animal cell that lacks the ability to produce GTP? A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. B) It could activate only the epinephrine system. C) It would be able to carry out reception and transduction, but would not be able to respond to a signal. D) Only A and C are true. E) A, B, and C are true.

A. It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

As humans, we have receptors for two kinds of beta adrenergic compounds such as catecholamines. Cardiac muscle cells have beta 1 receptors that promote increased heart rate. Some drugs that slow heart rate are called beta blockers. Smooth muscle cells, however, have beta 2 receptors which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. The description above illustrates which of the following? A) Just because a drug acts on one type of receptor does not mean that it will act on another type. B) Beta blockers can be used effectively on any type of muscle. C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites.

A. Just because a drug acts on one type of receptor does not mean that it will act on another type

When does the synaptonemal complex disappear? A) Late prophase of meiosis I B) During fertilization or fusion of gametes C) Early anaphase of meiosis I D) Mid-prophase of meiosis II E) Late metaphase of meiosis II

A. Late prophase of meiosis I

An ideal procedure for fetal testing in humans would have which of the following features? A) Lowest risk procedure that would provide the most reliable information B) The procedure that can test for the greatest number of traits at once C) A procedure that provides a 3D image of the fetus D) The procedure that can be performed at the earliest time in the pregnancy E) A procedure that could test for the carrier status of the fetus

A. Lowest risk procedure that would provide the most reliable information

Males are more often affected by sex-linked traits than females because A) males are hemizygous for the X chromosome. B) male hormones such as testosterone often alter the effects of mutations on the X chromosome. C) female hormones such as estrogen often compensate for the effects of mutations on the X. D) X chromosomes in males generally have more mutations than X chromosomes in females. E) mutations on the Y chromosome often worsen the effects of X-linked mutations.

A. Males are hemizygous for the X chromosome

The toxin of Vibrio cholerae causes profuse diarrhea because it A) modifies a G protein involved in regulating salt and water secretion. B) decreases the cytosolic concentration of calcium ions, making the cells hypotonic to the intestinal cells. C) binds with adenylyl cyclase and triggers the formation of cAMP. D) signals inositol trisphosphate to become a second messenger for the release of calcium. E) modifies calmodulin and activates a cascade of protein kinases.

A. Modifies a G protein involved in regulating salt and water secretion

The F1 offspring of Mendelʹs classic pea cross always looked like one of the two parental varieties because A) one phenotype was completely dominant over another. B) each allele affected phenotypic expression. C) the traits blended together during fertilization. D) no genes interacted to produce the parental phenotype. E) different genes interacted to produce the parental phenotype.

A. One phenotype was completely dominant over another

Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

A. PDGF

Which of the following most likely would be an immediate result of growth factor binding to its receptor? A) protein kinase activity B) adenylyl cyclase activity C) GTPase activity D) protein phosphatase activity E) phosphorylase activity

A. Protein kinase activity

A pedigree analysis for a given disorderʹs occurrence in a family shows that, although both parents of an affected child are normal, each of the parents has had affected relatives with the same condition. The disorder is then which of the following? A) Recessive B) Dominant C) Incompletely dominant D) Maternally inherited E) A new mutation

A. Recessive

Meiosis II is similar to mitosis in that A) sister chromatids separate during anaphase. B) DNA replicates before the division. C) the daughter cells are diploid. D) homologous chromosomes synapse. E) the chromosome number is reduced.

A. Sister chromatids separate during anaphase

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to A) the active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate. B) RNA specifying the amino acids in a polypeptide. C) a particular metabolic pathway operating within a specific organelle. D) an enzyme with an optimum pH and temperature for activity. E) genes making up a chromosome.

A. The active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate

The centromere is a region in which A) chromatids remain attached to one another until anaphase. B) metaphase chromosomes become aligned at the metaphase plate. C) chromosomes are grouped during telophase. D) the nucleus is located prior to mitosis. E) new spindle microtubules form at either end.

A. The chromatids remain attached to one another until anaphase

Which of the following statements is true? A) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. B) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. C) All of the traits that Mendel studied—seed color, pod shape, flower color, and others —are due to genes linked on the same chromosome. D) Linked genes are found on different chromosomes. E) Crossing over occurs during prophase II of meiosis.

A. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them

What is a genome? A) The complete complement of an organismʹs genes B) A specific set of polypeptides within each cell C) A specialized polymer of four different kinds of monomers D) A specific segment of DNA that is found within a prokaryotic chromosome E) An ordered display of chromosomes arranged from largest to smallest

A. The complete complement of an organisms genes

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect A) the fibers of the mitotic spindle. B) anaphase. C) formation of the centrioles. D) chromatid assembly. E) the S phase of the cell cycle.

A. The fibers of the mitotic spindle

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons? A) The frequency of crossing over varies along the length of the chromosome. B) The relationship between recombination frequency and map units is different in every individual. C) Physical distances between genes change during the course of the cell cycle. D) The gene order on the chromosomes is slightly different in every individual. E) Linkage map distances are identical between males and females.

A. The frequency of crossing over varies along the length of the chromosome

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? A) The gene involved is on the X chromosome. B) The gene involved is on the Y chromosome. C) The gene involved is on an autosome. D) Other male-specific factors influence eye color in flies. E) Other female-specific factors influence eye color in flies.

A. The gene involved is on the X chromosome

Independent assortment of chromosomes is a result of A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. B) the random nature of the fertilization of ova by sperm. C) the random distribution of the sister chromatids to the two daughter cells during anaphase II. D) the relatively small degree of homology shared by the X and Y chromosomes. E) All of the above

A. The random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

What does a frequency of recombination of 50% indicate? A) The two genes are likely to be located on different chromosomes. B) All of the offspring have combinations of traits that match one of the two parents. C) The genes are located on sex chromosomes. D) Abnormal meiosis has occurred. E) Independent assortment is hindered.

A. The two genes are likely to be located in different chromosomes

In 1956 Tijo and Levan first successfully counted human chromosomes. The reason it would have taken so many years to have done so would have included all but which of the following? A) Watson and Crickʹs structure of DNA was not done until 1953. B) Chromosomes were piled up on top of one another in the nucleus. C) Chromosomes were not distinguishable during interphase. D) A method had not yet been devised to halt mitosis at metaphase.

A. Watson and Crick's structure of DNA was not done until 1953

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger. A) cAMP B) G protein C) GTP D) adenylyl cyclase E) G protein-coupled receptor

A. cAMP

In tigers, a recessive allele causes an absence of fur pigmentation (a white tiger) and a cross-eyed condition. If two phenotypically normal tigers that are heterozygous at this locus are mated, what percentage of their offspring will be cross-eyed? What percentage will be white?

Answer: 25% will be cross-eyed; all of the cross-eyed offspring will also be white.

Two genes of a flower, one controlling blue (B) versus white (b) petals and the other controlling round (R) versus oval (r) stamens, are linked and are 10 map units apart. You cross a homozygous blue-oval plant with a homozygous white-round plant. The resulting F1 progeny are crossed with homozygous white-oval plants, and 1,000 F2 progeny are obtained. How many F2 plants of each of the four phenotypes do you expect?

Answer: 450 each of blue-oval and white-round (parentals) and 50 each of blue-round and white-oval (recombinants)

Phenylketonuria (PKU) is an inherited disease caused by a recessive allele. If a woman and her husband, who are both carriers, have three children, what is the probability of each of the following? A) All three children are of normal phenotype. B) One or more of the three children have the disease. C) All three children have the disease. D) At least one child is phenotypically normal. (Note: Remember that the probabilities of all possible outcomes always add up to 1.)

Answer: A)3⁄4×3⁄4×3⁄4=27⁄64,B)1—27⁄64=37⁄64,C)1⁄4×1⁄4×1⁄4=1⁄64,D)1—1⁄64=63 ⁄64

You design Drosophila crosses to provide recombination data for gene a, which is located on the chromosome shown in Figure 15.12 in the textbook. Gene a has recombination frequencies of 14% with the vestigial-wing locus and 26% with the brown-eye locus. Where is a located on the chromosome?

Answer: About one-third of the distance from the vestigial-wing locus to the brown-eye locus

A black guinea pig crossed with an albino guinea pig produces 12 black offspring. When the albino is crossed with a second black one, 7 blacks and 5 albinos are obtained. What is the best explanation for this genetic situation? Write genotypes for the parents, gametes, and offspring.

Answer: Albino (b) is a recessive trait; black (B) is dominant. First cross: parents BB × bb; gametes B and b; offspring all Bb (black coat). Second cross: parents Bb × bb; gametes 1⁄2 B and 1⁄2 b (heterozygous parent) and b; offspring 1⁄2 Bb and 1⁄/2 bb.

Bananas plants, which are triploid, are seedless and therefore sterile. Propose a possible explanation.

Answer: Because bananas are triploid, homologous pairs cannot line up during meiosis. Therefore, it is not possible to generate gametes that can fuse to produce a zygote with the triploid number of chromosomes.

A space probe discovers a planet inhabited by creatures that reproduce with the same hereditary patterns seen in humans. Three phenotypic characters are height ( T = tall, t = dwarf), head appendages (A = antennae, a = no antennae), and nose morphology (S = upturned snout, s = downturned snout). Since the creatures are not "intelligent," Earth scientists are able to do some controlled breeding experiments, using various heterozygotes in testcrosses. For tall heterozygotes with antennae, the offspring are: tall-antennae, 46; dwarf-antennae, 7; dwarf-no antennae, 42; tall-no antennae, 5. For heterozygotes with antennae and an upturned snout, the offspring are: antennae-upturned snout, 47; antennae-downturned snout, 2; no antennae-downturned snout, 48; no antennae-upturned snout, 3. Calculate the recombination frequencies for both experiments.

Answer: Between T and A, 12%; between A and S, 5%

What pattern of inheritance would lead a geneticist to suspect that an inherited disorder of cell metabolism is due to a defective mitochondrial gene?

Answer: The disorder would always be inherited from the mother.

In corn plants, a dominant allele I inhibits kernel color, while the recessive allele i permits color when homozygous. At a different locus, the dominant allele P causes purple kernel color, while the homozygous recessive genotype pp causes red kernels. If plants heterozygous at both loci are crossed, what will be the phenotypic ratio of the offspring?

Answer: The dominant allele I is epistatic to the P/p locus, and thus the genotypic ratio for the F1 generation will be 9 I_P_ (colorless) : 3 I_pp (colorless) : 3 iiP_ (purple) : 1 iipp (red). Overall, the phenotypic ratio is 12 colorless : 3 purple : 1 red.

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? A) 1 B) 1/2 C) 1/4 D) 1/6 E) 0

B. 1/2

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F 2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? A) 65 B) 190 C) 250 D) 565 E) 750

B. 190

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. How many genes must be responsible for these coat colors in Labrador retrievers? A) 1 B) 2 C) 3 D) 4

B. 2

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80

B. 20

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus 2. Alignment of tetrads at the metaphase plate 3. Separation of sister chromatids 4. Separation of the homologues; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs Which of the steps take place in both mitosis and meiosis? A) 2 B) 3 C) 5 D) 2 and 3 only E) 2, 3, and 5

B. 3

A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following? A) 63 chromosomes in 31 1/2 pairs B) 63 chromosomes in 21 sets of 3 C) 63 chromosomes, each with three chromatids D) 21 chromosome pairs and 21 unique chromosomes

B. 63 chromosomes in 21 sets of 3

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? A) 4 B) 8 C) 16 D) 32 E) 64

B. 8

What is a chromatid? A) a chromosome in G1 of the cell cycle B) a replicate chromosome C) a chromosome found outside the nucleus D) a special region that holds two centromeres together E) another name for the chromosomes found in genetics

B. A Replicate chromosome

Which of the following is an example of alternation of generations? A) A grandparent and grandchild each has dark hair, but the parent has blond hair. B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte). C) A diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote. D) A haploid mushroom produces gametes by mitosis, and the gametes undergo fertilization, which is immediately followed by meiosis. E) A diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetraploid cell.

B. A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to multicellular, haploid pollen grain (gametophyte)

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei re-forming on either side of the cell plate. This cell is most likely A) an animal cell in the process of cytokinesis. B) a plant cell in the process of cytokinesis. C) an animal cell in the S phase of the cell cycle. D) a bacterial cell dividing. E) a plant cell in metaphase.

B. A plant cell in the process of cytokinesis

Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

B. Anaphase

Density-dependent inhibition is explained by which of the following? A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors. B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing. C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. D) As cells become more numerous, more and more of them enter the S phase of the cell cycle. E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

B. As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing

A major group of G protein-linked receptors contain seven transmembrane alpha helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. Where would you expect to find the carboxyl end? A) at the exterior surface B) at the cytosol surface C) connected with the loop at H5 and H6 D) between the membrane layers

B. At the cytosol surface

Testosterone functions inside a cell by A) acting as a signal receptor that activates ion-channel proteins. B) binding with a receptor protein that enters the nucleus and activates specific genes. C) acting as a steroid signal receptor that activates ion-channel proteins. D) becoming a second messenger that inhibits adenylyl cyclase. E) coordinating a phosphorylation cascade that increases glycogen metabolism.

B. Binding with a receptor protein that enters the nucleus and activates specific genes

Membrane receptors that attach phosphates to specific animo acids in proteins are A) not found in humans. B) called receptor tyrosine-kinases. C) a class of GTP G-protein signal receptors. D) associated with several bacterial diseases in humans. E) important in yeast mating factors that contain amino acids.

B. Called receptor tyrosine-kinases

For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission? A) Binary fission would not allow for the formation of new organisms. B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes. C) Cell division would be faster than binary fission. D) Cell division allows for lower rates of error per chromosome replication. E) Binary fission would not allow the organism to have complex cells.

B. Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore

B. Centrosome

Correns described that the inheritance of variegated color on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe? A) Mitochondrial inheritance B) Chloroplast inheritance C) Genomic imprinting D) Infectious inheritance E) Sex-linkage

B. Chloroplast inheritance

If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will A) move directly into telophase. B) complete the cycle and divide. C) exit the cycle and switch to a nondividing state. D) show a drop in MPF concentration. E) complete cytokinesis and form new cell walls.

B. Complete the cycle and divide

New combinations of linked genes are due to which of the following? A) Nondisjunction B) Crossing over C) Independent assortment D) Mixing of sperm and egg E) Deletions

B. Crossing over

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways? A) There are four major functional classes of genes in Drosophila. B) Drosophila genes cluster into four distinct groups of linked genes. C) The overall number of genes in Drosophila is a multiple of four. D) The entire Drosophila genome has approximately 400 map units. E) Drosophila genes have, on average, four different alleles.

B. Drosophila genes cluster into four distinct groups of linked genes

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of A) incomplete dominance. B) epistasis. C) complete dominance. D) pleiotropy. E) codominance.

B. Epistasis

Abnormal chromosomes are frequent in malignant tumors. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse? A) An increase in non-disjunction B) Expression of inappropriate gene products C) A decrease in mitotic frequency D) Death of the cancer cells in the tumor E) Sensitivity of the immune system

B. Expression of inappropriate gene products

The ʺrestriction pointʺ occurs here: A) G0 B) G1 C) S D) G2 E) M

B. G1

15) Referring to a plant sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes? A) Sporophyte meiosis B) Gametophyte mitosis C) Gametophyte meiosis D) Sporophyte mitosis E) Alternation of generations

B. Gametophyte mitosis

Which of the following are primarily responsible for cytokinesis in plant cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and basal bodies E) cyclin-dependent kinases

B. Golgi-derived vesicles

I. Prophase II. Metaphase I III. Anaphase I IV. Telophase I IV. Prophase II VI. Metaphase II VII. Anaphase II VIII. Telophase II Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment. A) I B) II C) IV D) VII E) VIII

B. II

Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because A) only target cells retain the appropriate DNA segments. B) intracellular receptors are present only in target cells. C) most cells lack the Y chromosome required. D) only target cells possess the cytosolic enzymes that transduce the testosterone. E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

B. Intracellular receptors are present only in target cells

A small molecule that specifically binds to another molecule, usually a larger one A) is called a signal transducer. B) is called a ligand. C) is called a polymer. D) seldom is involved in hormonal signaling. E) usually terminates a signal reception.

B. Is called a ligand

Why did the improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics? A) It revealed new and unanticipated features of Mendelʹs pea plant varieties. B) It allowed the study of meiosis and mitosis, revealing parallels between behaviors of genes and chromosomes. C) It allowed scientists to see the DNA present within chromosomes. D) It led to the discovery of mitochondria. E) It showed genes functioning to direct the formation of enzymes.

B. It allowed the study of meiosis and mitosis, revealing parallels between behaviors of genes and chromosomes

Which of the following triggers the cellʹs passage past the G2 checkpoint into mitosis? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

B. MPF

Which of the following is true of the mating signal transduction pathway in yeast? A) The pathway carries an electrical signal between mating cell types. B) Mating type a secretes a signal called a factor. C) The molecular details of the pathway in yeast and in animals are very different. D) Scientists think the pathway evolved long after multicellular creatures appeared on Earth. E) The signal reception, transduction, and response occur in the nucleus.

B. Mating type secretes a signal called a factor

Homologous chromosomes move toward opposite poles of a dividing cell during A) mitosis. B) meiosis I. C) meiosis II. D) fertilization. E) binary fission.

B. Meiosis I

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype? A) Prophase B) Metaphase C) Anaphase D) Telophase E) Interphase

B. Metaphase

The somatic cells derived from a single-celled zygote divide by which process? A) meiosis B) mitosis C) replication D) cytokinesis alone E) binary fission

B. Mitosis

B. Molecules of purified receptor

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis? A) The chromosomes are ʺreeled inʺ by the contraction of spindle microtubules. B) Motor proteins of the kinetochores move the chromosomes along the 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

B. Motor proteins of the kinetochores move the chromosomes along the spindle microtubules

Which describes the ABO blood group system? A) Incomplete dominance B) Multiple alleles C) Pleiotropy D) Epistasis

B. Multiple alleles

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The manʹs father was six feet tall, and both the womanʹs parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their daughters might be expected to be color-blind dwarfs? A) All B) None C) Half D) One out of four E) Three out of four

B. None

One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant, although it may be either mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation? A) The mother carries the gene but does not express it at all. B) One of the parents has very mild expression of the gene. C) The condition skipped a generation in the family. D) The child has a different allele of the gene than the parents.

B. One of the parents has a very mild expression of the gene

It was important that Mendel examined not just the F 1 generation in his breeding experiments, but the F2 generation as well, because A) he obtained very few F1 progeny, making statistical analysis difficult. B) parental traits that were not observed in the F1 reappeared in the F2. C) analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment. D) the dominant phenotypes were visible in the F2 generation, but not in the F1. E) many of the F1 progeny died.

B. Parental traits that were not observed in the F1 reappeared in the F2

Which of the following does not occur during mitosis? A) condensation of the chromosomes B) replication of the DNA C) separation of sister chromatids D) spindle formation E) separation of the spindle poles

B. Replication of the DNA

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous ( Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red : 2 roan : 1 white? A) red × white B) roan × roan C) white × roan D) red × roan E) The answer cannot be determined from the information provided.

B. Roan x roan

The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the women teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results. What might be among their conclusions? A) The young women showed these results because they have poorer nutrition. B) The elderly personsʹ samples demonstrated their lowered immune responses. C) The young men had higher response because they are generally healthier. D) The patient samples should have had the lowest response but did not, so the experiment is invalid. E) The elderly donor samples represent cells no longer capable of any cell division.

B. The elderly persons samples demonstrated their lowered immune responses

Two characters that appear in a 9:3:3:1 ratio in the F 2 generation should have which of the following properties? A) Each of the traits is controlled by single genes. B) The genes controlling the characters obey the law of independent assortment. C) Each of the genes controlling the characters has two alleles. D) Four genes are involved. E) Sixteen different phenotypes are possible.

B. The genes controlling the characters obey the law of independent assortment

Affinity chromatography is a method that can be used to purify cell-surface receptors, while they retain their hormone-binding ability. A ligand (hormone) for a receptor of interest is chemically linked to polystyrene beads. A solubilized preparation of membrane proteins is passed over a column containing these beads. Only the receptor binds to the beads. When an excess of the ligand (hormone) is poured through the column after the receptor binding step, what do you expect will occur? A) The ligand will attach to those beads that have the receptor and remain on the column. B) The ligand will cause the receptor to be displaced from the beads and eluted out. C) The ligand will attach to the bead instead of the receptor. D) The ligand will cause the bead to lose its affinity by changing shape. E) The reaction will cause a pH change due to electron transfer.

B. The ligand will cause the receptor to be displaced from the beads and eluted out

Why has C. elegans proven to be a useful model for understanding apoptosis? A) The animal has very few genes, so that finding those responsible is easier than in a more complex organism. B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. C) This plant has a long-studied aging mechanism that has made understanding its death just a last stage. D) While the organism ages, its cells die progressively until the whole organism is dead. E) All of its genes are constantly being expressed so all of its proteins are available from each cell.

B. The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development

When pairs of homologous chromosomes separate during anaphase I, A) the maternal chromosomes all move to the same daughter cell. B) the sister chromatids remain attached to one another. C) recombination is not yet complete. D) the synaptonemal complex is visible under the light microscope.

B. The sister chromatids remain attached to one another

A cell divides to produce two daughter cells that are genetically different. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

B. The statement is true for meiosis I only

Homologous chromosomes synapse and crossing over occurs. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

B. The statement is true for meiosis I only

Independent assortment of chromosomes occurs. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

B. The statement is true for meiosis I only

Why do chromosomes coil during mitosis? A) to increase their potential energy B) to allow the chromosomes to move without becoming entangled and breaking C) to allow the chromosomes to fit within the nuclear envelope D) to allow the sister chromatids to remain attached E) to provide for the structure of the centromere

B. To allow the chromosomes to move without becoming entangled and breaking

A scientist discovers a DNA-based test for the allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Of the following, which is the best use of this discovery? A) To screen all newborns of an at-risk population B) To design a test for identifying heterozygous carriers of the allele C) To introduce a normal allele into deficient newborns D) To follow the segregation of the allele during meiosis E) To test school-age children for the disorder

B. To design a test for identifying heterozygous carriers of the allele

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A) There is considerable genetic variation in garden peas. B) Traits are inherited in discrete units, and are not the results of ʺblending.ʺ C) Recessive genes occur more frequently in the F1 than do dominant ones. D) Genes are composed of DNA. E) An organism that is homozygous for many recessive traits is at a disadvantage.

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

B. What is the length of the S phase of the cell cycle

The process of transduction usually begins A) when the chemical signal is released from the alpha cell. B) when the signal molecule changes the receptor protein in some way. C) after the target cell divides. D) after the third stage of cell signaling is completed. E) when the hormone is released from the gland into the blood.

B. When the signal molecule changes the receptor protein in some way

A woman has six sons. The chance that her next child will be a daughter is A) 1. B) 0. C) 1/2. D) 1/6. E) 5/6.

C. 1/2

Huntingtonʹs disease is a dominant condition with late age of onset in humans. If one parent has the disease, what is the probability that his or her child will have the disease? A) 1 B) 3/4 C) 1/2 D) 1/4 E) 0

C. 1/2

Cystic fibrosis (CF) is a Mendelian disorder in the human population that is inherited as a recessive. Two normal parents have two children with CF. The probability of their next child being normal for this characteristic is which of the following? A) 0 B) 1/2 C) 1/4 D) 3/4 E) 1/8

C. 1/4

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis? A) All the gametes will be diploid. B) Half of the gametes will be n + 1, and half will be n — 1. C) 1/4 of the gametes will be n + 1, one will be n — 1, and two will be n. D) There will be three extra gametes. E) Two of the four gametes will be haploid, and two will be diploid.

C. 1/4 of the gametes will be n+1, one will be n-1 and two will be n

Given the parents AABBCc × AabbCc, assume simple dominance and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent? A) 1/4 B) 1/8 C) 3/4 D) 3/8 E) 1

C. 3/4

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system? A) 1 B) 2 C) 4 D) 8 E) 16

C. 4

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. 50%

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils. B) sister chromatids are identical, but they differ from one another in animals. C) a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage. D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase. E) spindle poles contain centrioles, whereas spindle poles in animals do not.

C. A cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following? A) lower cytoplasmic levels of cAMP B) an increase in receptor tyrosine kinase activity C) a decrease in transcriptional activity of certain genes D) an increase in cytosolic calcium concentration E) a decrease in G-protein activity

C. A decrease in transcriptional activity of certain genes

What is the difference between a monohybrid cross and a dihybrid cross? A) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents. B) A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. C) A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one. D) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. E) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

C. A dihybrid cross involves organisms that are heterozygous for two characters and a mono hybrid only one

If an adult person has a faulty version of the human-analog to ced-4 of the nematode, which of the following might more likely result? A) neurodegeneration B) activation of a developmental pathway found in the worm but not in humans C) a form of cancer in which there is insufficient apoptosis D) webbing of fingers or toes E) excess skin exfoliation

C. A form of cancer in which there is insufficient apoptosis

Women with Turner syndrome have a genotype characterized as which of the following? A) aabb B) Mental retardation and short arms C) A karyotype of 45, X D) A karyotype of 47, XXX E) A deletion of the Y chromosome

C. A karyotype of 45, X

G proteins and G-protein-linked receptors A) are found only in animal cells, and only embedded in or located just beneath the cellʹs membrane. B) are found only in bacterial cells, embedded in the cellʹs plasma membrane only. C) are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms. D) probably evolved from an adaptation of the citric acid cycle. E) are not widespread in nature and were unimportant in the evolution of eukaryotes.

C. Are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible phenotype for the father? A) A negative B) O negative C) B positive D) AB negative E) Impossible to determine

C. B positive

Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Chromosomally abnormal cells can still go through cell cycle checkpoints. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.

C. Chromosomally abnormal cells can still go through cell cycle checkpoints

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants? A) Backtrack through her previous experiments to obtain another plant with the same traits. B) Breed this plant with another plant with much weaker traits. C) Clone the plant asexually to produce an identical one. D) Force the plant to self-pollinate to obtain an identical one. E) Add nitrogen to the soil of the offspring of this plant so the desired traits continue.

C. Clone the plant asexually to produce an identical one

In order for anaphase to begin, which of the following must occur? A) Chromatids must lose their kinetochores. B) Cohesin must attach the sister chromatids to each other. C) Cohesin must be cleaved enzymatically. D) Kinetochores must attach to the metaphase plate. E) Spindle microtubules must begin to depolymerize.

C. Cohesin must be cleaved enzymatically

Experiments with cohesions have found that A) cohesions are protected from destruction throughout meiosis I and II. B) cohesions are cleaved from chromosomes at the centromere before anaphase I. C) cohesions are protected from cleavage at the centromere during meiosis I. D) a protein cleaves cohesions before metaphase I. E) a protein that cleaves cohesions would cause cellular death.

C. Cohesions are protected from cleaved at the centromere during meiosis I

One difference between cancer cells and normal cells is that cancer cells A) are unable to synthesize DNA. B) are arrested at the S phase of the cell cycle. C) continue to divide even when they are tightly packed together. D) cannot function properly because they are affected by density-dependent inhibition. E) are always in the M phase of the cell cycle.

C. Continue to divide even when they are tightly packed together

What is the mechanism for the production of genetic recombinants? A) X inactivation B) Methylation of cytosine C) Crossing over and independent assortment D) Nondisjunction E) Deletions and duplications during meiosis

C. Crossing over and independent assortment

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? A) Mendelʹs law of independent assortment B) Mendelʹs law of segregation C) Darwinʹs explanation of natural selection D) Darwinʹs observations of competition E) The malarial parasite changing the allele

C. Darwin's explanation of natural selection

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates A) the blending model of genetics. B) true-breeding. C) dominance. D) a dihybrid cross. E) the mistakes made by Mendel.

C. Dominance

Which of the following is true of a species that has a chromosome number of 2n = 16? A) The species is diploid with 32 chromosomes per cell. B) The species has 16 sets of chromosomes per cell. C) Each cell has 8 homologous pairs. D) During the S phase of the cell cycle there will be 32 separate chromosomes. E) A gamete from this species has 4 chromosomes.

C. Each cell has 8 homologous pairs

Which of the following is a correct association? A) kinase activity and the addition of a tyrosine B) phosphodiesterase activity and the removal of phosphate groups C) GTPase activity and hydrolysis of GTP to GDP D) phosphorylase activity and the catabolism of glucose E) adenylyl cyclase activity and the conversion of cAMP to AMP

C. GTPase activity and hydrolysis of GTP to GDP

Which observation suggested to Sutherland the involvement of a second messenger in epinephrineʹs effect on liver cells? A) Enzymatic activity was proportional to the amount of calcium added to a cell -free extract. B) Receptor studies indicated that epinephrine was a ligand. C) Glycogen breakdown was observed only when epinephrine was administered to intact cells. D) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. E) Epinephrine was known to have different effects on different types of cells.

C. Glycogen breakdown was observed only when epinephrine was administered to intact cells

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

C. In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing

A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of A) complete dominance. B) multiple alleles. C) incomplete dominance. D) polygenic inheritance. E) pleiotropy.

C. Incomplete dominance

A man with Klinefelter syndrome (47, XXY) is expected to have any of the following EXCEPT A) lower sperm count. B) possible breast enlargement. C) increased testosterone. D) long limbs. E) female body characteristics.

C. Increased testosterone

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times. The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that A) the presence of the pathogen made the experiment too contaminated to trust the results. B) their tissue culture methods needed to be relearned. C) infection causes lymphocytes to divide more rapidly. D) infection causes cell cultures in general to reproduce more rapidly. E) infection causes lymphocyte cultures to skip some parts of the cell cycle.

C. Infection causes lymphocytes to divide more rapidly

Which of the following is the best explanation for the inability of an animal cell to reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid? A) blockage of the synaptic signal B) loss of transcription factors C) insufficient ATP levels in the cytoplasm D) low oxygen concentration around the cell E) low levels of protein kinase in the cell

C. Insufficient ATP levels in the cytoplasm

An enzyme that attaches a phosphate group to another molecule is called a A) phosphatase. B) phosphorylase. C) kinase. D) cyclase. E) ATPase.

C. Kinase

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? A) metastasis B) changes in the order of cell cycle stages C) lack of appropriate cell death D) inability to form spindles E) inability of chromosomes to meet at the metaphase plate

C. Lack of appropriate cell death

What are scaffolding proteins? A) ladder-like proteins that allow receptor-ligand complexes to climb through cells from one position to another B) microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores C) large molecules to which several relay proteins attach to facilitate cascade effects D) relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing E) proteins that can reach into the nucleus of a cell to affect transcription

C. Large molecules to which several relay proteins attach to facilitate cascade effects

A geneʹs location along a chromosome is known as which of the following? A) Allele B) Sequence C) Locus D) Variant E) Trait

C. Locus

When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is A) typical of hormones. B) autocrine signaling. C) paracrine signaling. D) endocrine signaling. E) synaptic signaling.

C. Paracrine signaling

Adenylyl cyclase has the opposite effect of which of the following? A) protein kinase B) protein phosphatase C) phosphodiesterase D) phosphorylase E) GTPase

C. Phosphodiesterase

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) Incomplete dominance B) Multiple alleles C) Pleiotropy D) Epistasis

C. Pleiotrophy

Which describes the ability of a single gene to have multiple phenotypic effects? A) Incomplete dominance B) Multiple alleles C) Pleiotropy D) Epistasis

C. Pleitrophy

Which term describes two centrosomes arranged at opposite poles of the cell? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

C. Prometaphase

Chromosomes first become visible during which phase of mitosis? A) prometaphase B) telophase C) prophase D) metaphase E) anaphase

C. Prophase

The general name for an enzyme that transfers phosphate groups from ATP to a protein is A) phosphorylase. B) phosphatase. C) protein kinase. D) ATPase. E) protease.

C. Protein kinase

Which is a general term for enzymes that activate or inactivate other proteins by phosphorylating them? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

C. Protein kinase

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize a particular amino acid. This amino acid is not otherwise produced by humans. Therefore the most efficient and effective treatment is which of the following? A) Feed them the substrate that can be metabolized into this amino acid. B) Transfuse the patients with blood from unaffected donors. C) Regulate the diet of the affected persons to severely limit the uptake of the amino acid. D) Feed the patients the missing enzymes in a regular cycle, i.e., twice per week.

C. Regulate the diet of the affected persons to severely limit the uptake of amino acid

You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide? A) A visible nuclear envelope B) Separated sister chromatids at each pole of the cell C) Tetrads lined up at the center of the cell D) A synaptonemal complex E) A cleavage furrow

C. Tetrads lined up at the center of the cell

A particular cyclin called cyclin E forms a complex with a cyclin-dependent kinase called Cdk 2. This complex is important for the progression of the cell from G1 into the S phase of the cell cycle. Which of the following statements is correct? A) The amount of cyclin E is greatest during the S phase. B) The amount of Cdk 2 is greater during G1 compared to the S phase. C) The amount of cyclin E is highest during G1. D) The amount of Cdk 2 is greatest during G1. E) The activity of the cyclin E/Cdk 2 complex is highest during G2.

C. The amount of cyclin E is highest during G1

The decline of MPF activity at the end of mitosis is due to A) the destruction of the protein kinase Cdk. B) decreased synthesis of cyclin. C) the degradation of cyclin. D) synthesis of DNA. E) an increase in the cellʹs volume-to-genome ratio.

C. The degradation of cyclin

Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility, and death, usually of coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the following represents the most likely assumption? A) All cases must occur in relatives; therefore, there must be only one mutant allele. B) Successive generations of a family will continue to have more and more cases over time. C) The disorder may be due to mutation in a single protein-coding gene. D) Each patient will have had at least one affected family member in a previous generation. E) The disease is autosomal dominant.

C. The disorder may be due to mutation in a single protein-coding gene

A karyotype results from which of the following? A) A natural cellular arrangement of chromosomes in the nucleus B) An inherited ability of chromosomes to arrange themselves C) The ordering of human chromosome images D) The cutting and pasting of parts of chromosomes to form the standard array E) The separation of homologous chromosomes at metaphase I of meiosis

C. The ordering of human chromosome images

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because A) they are species specific. B) they always lead to the same cellular response. C) they amplify the original signal manyfold. D) they counter the harmful effects of phosphatases. E) the number of molecules used is small and fixed.

C. They amplify the original manyfold

As humans, we have receptors for two kinds of beta adrenergic compounds such as catecholamines. Cardiac muscle cells have beta 1 receptors that promote increased heart rate. Some drugs that slow heart rate are called beta blockers. Smooth muscle cells, however, have beta 2 receptors which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. The use of beta 2 antagonist drugs may be useful in asthma because A) they may increase constriction of the skeletal muscle of the chest wall. B) they may increase heart rate and therefore allow the patient to get more oxygen circulated. C) they may dilate the bronchioles by relaxing their smooth muscle. D) they may override the beta blockers that the patient is already taking. E) they may obstruct all G protein-mediated receptors.

C. They may dilute the bronchioles by relaxing their smooth muscle

Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesions. Such molecules must have which of the following properties? A) They must persist throughout the cell cycle. B) They must be removed before meiosis can begin. C) They must be removed before anaphase can occur. D) They must reattach to chromosomes during G1. E) They must be intact for nuclear envelope reformation.

C. They must be removed before anaphase can occur

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that A) new mutations were frequently generated in the F2 progeny, ʺreinventingʺ traits that had been lost in the F1. B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1. D) the traits were lost in the F1 due to blending of the parental traits. E) members of the F1 generation had only one allele for each character, but members of the F2 had two alleles for each character.

C. Traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. In one type cross of black × black, the results were as follows: 9/16 black 4/16 yellow 3/16 brown The genotype aabb must result in which of the following? A) Black B) Brown C) Yellow D) A lethal result

C. Yellow

In animals, meiosis results in gametes, and fertilization results in A) spores. B) gametophytes. C) zygotes. D) sporophytes. E) clones.

C. Zygotes

Which of the following are chemical messengers that pass through the plasma membrane of cells and have receptor molecules in the cytoplasm? A) insulin B) testosterone C) cAMP D) epinephrine

C. cAMP

Morgan and his colleagues worked out a set of symbols to represent fly genotypes. Which of the following are representative? A) AaBb × AaBb B) 46, XY or 46, XX C) vg+vgse+se × vgvgsese D) +2 × +3

C. vg+vgse+se x vgvgsese

If we continued to follow the cell lineage from question 5, then the DNA content of a single cell at metaphase of meiosis II would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x.

C. x

Feather color in budgies is determined by two different genes Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. Two blue budgies were crossed. Over the years, they produced 22 offspring, 5 of which were white. What are the most likely genotypes for the two blue budgies? A) yyBB and yyBB B) yyBB and yyBb C) yyBb and yyBb D) yyBB and yybb E) yyBb and yybb

C. yyBb and yyBb

Chiasmata are what we see under a microscope that let us know which of the following is occurring? A) Asexual reproduction B) Meiosis II C) Anaphase II D) Crossing over E) Separation of homologs

D. Crossing over

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) protein kinase D) cyclin E) Cdk

D. Cyclin

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 × BBtt will have black fur and long tails? A) 1/16 B) 3/16 C) 3/8 D) 1/2 E) 9/16

D. 1/2

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)? A) 2 B) 4 C) 8 D) 16 E) 32

D. 16

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. Those cells would have __________ picograms at the end of the S phase and __________ picograms at the end of G 2. A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 E) 12; 16

D. 16;16

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x.

D. 2x

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 4 B) 8 C) 16 D) 32 E) 64

D. 32

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes? A) 12 B) 16 C) 23 D) 46 E) 92

D. 46

A gene is considered to be non-Mendelian in its inheritance pattern if it seems to ʺviolateʺ Mendelʹs laws. Which of the following would then NOT be considered non-Mendelian? A) A gene whose expression varies depending on the gender of the transmitting parent B) A gene derived solely from maternal inheritance C) A gene transmitted via the cytoplasm or cytoplasmic structures D) A gene transmitted to males from the maternal line and from fathers to daughters E) A gene transmitted by a virus to egg-producing cells

D. A gene transmitted to males from the maternal line and from fathers to daughters

The fact that all seven of the pea plant 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) The diploid number of chromosomes in the pea plants was 7. C) All of the genes controlling the traits were located on the same chromosome. D) All of the genes controlling the traits behaved as if they were on different chromosomes. E) The formation of gametes in plants occurs by mitosis only.

D. All of the genes controlling the traits behaved as if they were in different chromosomes.

Mendelʹs observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? A) Prophase I of meiosis B) Prophase II of meiosis C) Metaphase I of meiosis D) Anaphase I of meiosis E) Anaphase of mitosis

D. Anaphase I of meiosis

Which of these statements is false? A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome. B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY). C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote. D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis. E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization.

D. At sexual maturity, ovaries and tested produce diploid gametes by meiosis

In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis? A) seedless plants B) dinoflagellates C) diatoms D) B and C only E) A, B, and C

D. B and C only

The main proteases involved in apoptosis are A) ced-3 and ced-4. B) inactive. C) cytochromes. D) caspases. E) G proteins.

D. Caspases

In order for chromosomes to undergo inversion or translocation, which of the following is required? A) Point mutation B) Immunological insufficiency C) Advanced maternal age D) Chromosome breakage and rejoining E) Meiosis

D. Chromosome breakage and rejoining

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to A) design a compound that mimics epinephrine and can bind to the epinephrine receptor. B) design a compound that stimulates cAMP production in liver cells. C) design a compound to stimulate G protein activity in liver cells. D) design a compound that increases phosphodiesterase activity. E) All of the above are possible approaches.

D. Design a compound that increases phosphodiesterase activity

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 is produced in very large concentration and therefore diffuses widely. B) Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding. C) Estrogen is kept away from the surface of any cells not able to bind it at the surface. D) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding. E) Estrogen has different shaped receptors for each of several cell types.

D. Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding

If the cell whose nuclear material is shown in Figure 12.2 continues toward completion of mitosis, which of the following events would occur next? A) cell membrane synthesis B) spindle fiber formation C) nuclear envelope breakdown D) formation of telophase nuclei E) synthesis of chromatids

D. Formation of telophase nuclei

Up to 60% of all medicines used today exert their effects by influencing what structures in the cell membrane? A) tyrosine-kinases receptors B) ligand-gated ion channel receptors C) growth factors D) G proteins E) cholesterol

D. G proteins

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA? A) G0 B) G1 C) S D) G2 E) M

D. G2

Feather color in budgies is determined by two different genes Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. A blue budgie is crossed with a white budgie. Which of the following results is not possible? A) Green offspring only B) Yellow offspring only C) Blue offspring only D) Green and yellow offspring E) a 9:3:3:1 ratio

D. Green and yellow offspring

After telophase I of meiosis, the chromosomal makeup of each daughter cell is A) diploid, and the chromosomes are each composed of a single chromatid. B) diploid, and the chromosomes are each composed of two chromatids. C) haploid, and the chromosomes are each composed of a single chromatid. D) haploid, and the chromosomes are each composed of two chromatids. E) tetraploid, and the chromosomes are each composed of two chromatids.

D. Haploid, and the chromosomes are each composed of two chromatids

D. IAi

D. IAiRr

D. IBi

The human X and Y chromosomes A) are both present in every somatic cell of males and females alike. B) are of approximately equal size and number of genes. C) are almost entirely homologous, despite their different names. D) include genes that determine an individualʹs sex. E) include only genes that govern sex determination.

D. Include genes that determine an individuals sex

The flower color trait in radishes is an example of which of the following? A) A multiple allelic system B) Sex linkage C) Codominance D) Incomplete dominance E) Epistasis

D. Incomplete dominance

Synaptic signaling between adjacent neurons is like hormone signaling in which of the following ways? A) It sends its signal molecules through the blood. B) It sends its signal molecules quite a distance. C) It requires calcium ions. D) It requires binding of a signaling molecule to a receptor. E) It persists over a long period.

D. It requires binding of a signaling molecule to a receptor

Which of the following describes the events of apoptosis? A) The cell dies, it is lysed, its organelles are phagocytized, its contents are recycled. B) Its DNA and organelles become fragmented, it dies, and it is phagocytized. C) The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. D) Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests. E) Its nucleus and organelles are lysed, the cell enlarges and bursts.

D. It's DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests

What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of its complex with a cyclin E) the binding of PDGF to receptors on the cell surface

D. It's destruction by a process initiated by the activity of its complex with a cyclin

Binding of a signaling molecule to which type of receptor leads directly to a change in distribution of ions on opposite sides of the membrane? A) receptor tyrosine kinase B) G protein-coupled receptor C) phosphorylated receptor tyrosine kinase dimer D) ligand-gated ion channel E) intracellular receptor

D. Ligand-gated ion channel

Apoptosis involves all but the following: A) fragmentation of the DNA B) cell-signaling pathways C) activation of cellular enzymes D) lysis of the cell E) digestion of cellular contents by scavenger cells

D. Lysis of the cell

Which of the following is a function of those spindle microtubules that do not attach to kinetochores? A) maintaining an appropriate spacing among the moving chromosomes B) producing a cleavage furrow when telophase is complete C) providing the ATP needed by the fibers attached to kinetochores D) maintaining the region of overlap of fibers in the cellʹs center E) pulling the poles of the spindles closer to one another

D. Maintaining the region of overlap of fibers in the cells center

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase D) metaphase E) interphase

D. Metaphase

Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis? A) telophase B) prophase C) anaphase D) metaphase E) prometaphase

D. Metaphase

Which is the longest of the mitotic stages? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

D. Metaphase

Genomic imprinting is generally due to the addition of methyl (-CH3) groups to C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true? A) Methylation of C is permanent in a gene. B) Genes required for early development stages must not be imprinted. C) Methylation of this kind must occur more in males than in females. D) Methylation must be reversible in ovarian and testicular cells. E) The imprints are transmitted only to gamete-producing cells.

D. Methylation must be reversible in ovarian and testicular cells

Which life cycle stage is found in plants but not animals? A) Gamete B) Zygote C) Multicellular diploid D) Multicellular haploid E) Unicellular diploid

D. Multicellular haploid

Asexual reproduction results in identical offspring unless which of the following occurs? A) Natural selection B) Cloning C) Crossing over D) Mutation E) Environmental change

D. Mutation

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore in which body systems would you expect most mitochondrial gene mutations to be exhibited? A) The immune system and the blood B) Excretory and respiratory systems C) The skin and senses D) Nervous and muscular systems E) Circulation

D. Nervous and muscular systems

What is the source of the extra chromosome 21 in an individual with Down syndrome? A) Nondisjunction in the mother only B) Nondisjunction in the father only C) Duplication of the chromosome D) Nondisjunction or translocation in either parent E) It is impossible to detect with current technology

D. Nondisjunction or translocation in either parent

A woman is found to have 47 chromosomes, including 3 X chromosomes. Which of the following describes her expected phenotype? A) Masculine characteristics such as facial hair B) Enlarged genital structures C) Excessive emotional instability D) Normal female E) Sterile female

D. Normal female

Pea plants were particularly well suited for use in Mendelʹs breeding experiments for all of the following reasons except that A) peas show easily observed variations in a number of characters, such as pea shape and flower color. B) it is possible to control matings between different pea plants. C) it is possible to obtain large numbers of progeny from any given cross. D) peas have an unusually long generation time. E) many of the observable characters that vary in pea plants are controlled by single genes.

D. Peas have an unusually long generation time

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? A) tyrosine kinases B) serine/threonine kinases C) phosphodiesterase D) phospholipase C E) adenylyl cyclase

D. Phospholipase C

Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations. B) increases cyclin concentrations. C) prevents elongation of microtubules. D) prevents shortening of microtubules. E) prevents attachment of the microtubules to the kinetochore.

D. Prevents shortening of microtubules

An inhibitor of phosphodiesterase activity would have which of the following effects? A) block the response of epinephrine B) decrease the amount of cAMP in the cytoplasm C) block the activation of G proteins in response to epinephrine binding to its receptor D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm E) block the activation of protein kinase A

D. Prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true breeding white oval radishes, the F1 will be expected to be which of the following? A) Red and long B) Red and oval C) White and long D) Purple and long E) Purple and oval

D. Purple and long

One of the major categories of receptors in the plasma membrane reacts by forming dimmers, adding phosphate groups, then activating relay proteins. Which type does this? A) G protein-linked receptor B) ligand-gated ion channels C) steroid receptors D) receptor tyrosine kinases

D. Receptor tyrosine kinases

The receptors for a group of signaling molecules known as growth factors are often A) ligand-gated ion channels. B) G-protein-linked receptors. C) cyclic AMP. D) receptor tyrosine kinases. E) neurotransmitters.

D. Receptor tyrosine kinases

Natural selection and recombination due to crossing over during meiosis I are related in which of the following ways? A) Recombinants are usually selected against. B) Non-recombinant organisms are usually favored by natural selection if there is environmental change. C) Most recombinants reproduce less frequently than do non-recombinants. D) Recombinants may have combinations of traits that are favored by natural selection. E) Recombination does not affect natural selection.

D. Recombinants May have combinations of traits that are favored by natural selection

The termination phase of cell signaling requires which of the following? A) removal of the receptor B) activation of a different set of relay molecules C) converting ATP to camp D) reversing the binding of signal molecule to the receptor E) apoptosis

D. Reversing the binding of signal molecule to the receptor

Which of the substances below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor? A) active transcription factor B) third messenger C) ligand D) scaffolding protein E) protein kinase

D. Scaffolding protein

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests A) that the parents were true-breeding for contrasting traits. B) incomplete dominance. C) that a blending of traits has occurred. D) that the parents were both heterozygous. E) that each offspring has the same alleles.

D. That the parents were both heterozygous

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 amount of cytoplasm and half the amount of DNA. B) The daughter cells have half the number of chromosomes and half the amount of DNA. C) The daughter cells have the same number of chromosomes and half the amount of DNA. D) The daughter cells have the same number of chromosomes and the same amount of DNA. E) The daughter cells have the same number of chromosomes and twice the amount of DNA.

D. The daughter cells have the same number of chromosomes and the same amount of DNA

Most genes have many more than two alleles. However, which of the following is also true? A) At least one allele for a gene always produces a dominant phenotype. B) Most of the alleles will never be found in a live-born organism. C) All of the alleles but one will produce harmful effects if homozygous. D) There may still be only two phenotypes for the trait. E) More than two alleles in a genotype is lethal.

D. There may still be only two phenotypes for the trait

Which is true of transcription factors? A) They regulate the synthesis of DNA in response to a signal. B) Some transcribe ATP into cAMP. C) They initiate the epinephrine response in animal cells. D) They control which genes are expressed. E) They are needed to regulate the synthesis of lipids in the cytoplasm.

D. They control which genes are expressed

How do cells at the completion of meiosis compare 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) They have half the number of chromosomes and half the amount of DNA. C) They have the same number of chromosomes and half the amount of DNA. D) They have half the number of chromosomes and one-fourth the amount of DNA. E) They have half the amount of cytoplasm and twice the amount of DNA.

D. They have half the number of chromosomes and one-fourth the amount of DNA

Several organisms, primarily Protists, have what are called intermediate mitotic organization. These Protists are intermediate in what sense? A) They reproduce by binary fission in their early stages of development and by mitosis when they are mature. B) They never coil up their chromosomes when they are dividing. C) They use mitotic division but only have circular chromosomes. D) They maintain a nuclear envelope during division. E) None of them form spindles.

D. They maintain a nuclear envelope during division

What could happen to the target cells in an animal that lack receptors for local regulators? A) They could compensate by receiving nutrients via an a factor. B) They could develop normally in response to neurotransmitters instead. C) They could divide but never reach full size. D) They would not be able to multiply in response to growth factors from nearby cells. E) Hormones would not be able to interact with target cells.

D. They would not be able to multiply in response to growth factors from nearby cells

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? A) Tortoiseshell females; tortoiseshell males B) Black females; orange males C) Orange females; orange males D) Tortoiseshell females; black males E) Orange females; black males

D. Tortoiseshell females; black males

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A) Deletion B) Disjunction C) Inversion D) Translocation E) Duplication

D. Translocation

Tallness (T) in snapdragons is dominant to dwarfness (t), while 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? A) ttRr-dwarf and pink B) ttrr-dwarf and white C) TtRr-tall and red D) TtRr-tall and pink E) TTRR-tall and red

D. TtRr- tall and pink

Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with A) a single large nucleus. B) high concentrations of actin and myosin. C) two abnormally small nuclei. D) two nuclei. E) two nuclei but with half the amount of DNA.

D. Two nuclei

What is the chromosomal system for determining sex in mammals? A) Haploid-diploid B) X-0 C) X-X D) X-Y E) Z-W

D. X-Y

Which of the following describe(s) cyclin-dependent kinase (Cdk)? A) Cdk is inactive, or ʺturned off,ʺ in the presence of cyclin. B) Cdk is present throughout the cell cycle. C) Cdk is an enzyme that attaches phosphate groups to other proteins. D) Both A and B are true. E) Both B and C are true.

E. Both B and C are true

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The manʹs father was six feet tall, and both the womanʹs parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes? A) 0 B) 0.25 C) 0.50 D) 0.75 E) 1.00

E. 1.00

In a cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? A) 1/4 B) 1/8 C) 1/16 D) 1/32 E) 1/64

E. 1/64

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes? A) 0% B) 25% C) 50% D) 75% E) 100%

E. 100%

In snapdragons, heterozygotes for one of the genes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers? A) 0% B) 25% C) 50% D) 75% E) 100%

E. 100%

If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase? A) 1 B) 2 C) 4 D) 8 E) 16

E. 16

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus 2. Alignment of tetrads at the metaphase plate 3. Separation of sister chromatids 4. Separation of the homologues; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs From the descriptions above, which of the following is the order that most logically illustrates a sequence of meiosis? A) 1, 2, 3, 4, 5 B) 5, 4, 2, 1, 3 C) 5,3,2,4,1 D) 4, 5, 2, 1, 3 E) 5, 2, 4, 3, 1

E. 5,2,4,3,1

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. In the F2 generation of the above cross, which of the following phenotypic ratios would be expected? A) 9:3:3:1 B) 9:4:3 C) 1:1:1:1 D) 1:1:1:1:1:1 E) 6:3:3:2:1:1

E. 6:3:3:2:1:1

In humans, male-pattern baldness is controlled by an autosomal gene that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald? A) 0% B) 25% C) 33% D) 50% E) 75%

E. 75%

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether cactuses have spines. Homozygous recessive nn cactuses have no spines at all. If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F2 would segregate in which of the following ratios? A) 3 sharp-spined : 1 spineless B) 1 sharp-spined : 2 dull-spined : 1 spineless C) 1 sharp spined : 1 dull-spined : 1 spineless D) 1 sharp-spined : 1 dull-spined E) 9 sharp-spined : 3 dull-spined : 4 spineless

E. 9 sharp-spined: 3 dull-spined: 4 spineless

What is a karyotype? A) The set of unique physical characteristics that define an individual B) The collection of all the mutations present within the genome of an individual C) The combination of chromosomes found in a gamete D) A system of classifying cell nuclei E) A display of every pair of homologous chromosomes within a cell, organized according to size and shape

E. A display of every pair of homologous chromosomes within a cell, organized according to size and shape

The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is this? A) an animal cell in metaphase B) an animal cell in telophase C) an animal cell undergoing cytokinesis D) a plant cell in metaphase E) a plant cell undergoing cytokinesis

E. A plant cell undergoing cytokinesis

Which of the following is (are) true of ligand-gated ion channels? A) They are important in the nervous system. B) They lead to changes in sodium and calcium concentrations in cells. C) They open or close in response to a chemical signal. D) Only A and B are true. E) A, B, and C are true.

E. A, B, and C are true

Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) B and C only E) A, B, and C

E. A,B, and C

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 23 B) 46 C) 460 D) 920 E) About 8 million

E. About 8 million

People with sickle-cell trait A) are heterozygous for the sickle-cell allele. B) are usually healthy. C) have increased resistance to malaria. D) produce normal and abnormal hemoglobin. E) All of the above

E. All of the above

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to A) design a compound that blocks epinephrine receptor activation. B) design a compound that inhibits cAMP production in liver cells. C) design a compound to block G-protein activity in liver cells. D) design a compound that inhibits phosphorylase activity. E) All of the above are possible approaches.

E. All of the above are possible approaches

Asexual reproduction and sexual reproduction differ in all but which of the following ways? A) Individuals reproducing asexually transmit 100% of their genes to their progeny, whereas individuals reproducing sexually transmit only 50%. B) Asexual reproduction produces offspring that are genetically identical to the parents, whereas sexual reproduction gives rise to genetically distinct offspring. C) Asexual reproduction involves a single parent, whereas sexual reproduction involves two. D) Asexual reproduction requires only mitosis, whereas sexual reproduction always involves meiosis. E) Asexual reproduction is utilized only by fungi and protists, whereas sexual reproduction is utilized only by plants and animals.

E. Asexual reproduction is utilized only by fungi and Protists, whereas sexual reproduction is utilized only by plants and animals

A major group of G protein-linked receptors contain seven transmembrane alpha helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. The coupled G protein most likely interacts with this receptor A) at the NH3 end B) at the COO- end C) along the exterior margin D) along the interior margin E) at the loop between H5 and H6

E. At the loop between H5 and H6

Which of the following statements is true? A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. B) In response to some G-protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. E) Protein kinase A activation is one possible result of signal molecules binding to G protein-linked receptors.

E. Protein kinase A activation is one possible result of signal molecules binding to G protein-linked receptors

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins? A) G-protein-linked receptor signaling B) ligand-gated ion channel signaling C) adenylyl cyclase activity D) phosphatase activity E) receptor tyrosine kinase activity

E. Receptor tyrosine kinase activity

Which of the following is an example of polygenic inheritance? A) Pink flowers in snapdragons B) The ABO blood groups in humans C) Huntingtonʹs disease in humans D) White and purple flower color in peas E) Skin pigmentation in humans

E. Skin pigmentation in humans

A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.

E. The cell would undergo normal mitosis, but fail to enter the next G1 phase

Chromatids are separated from each other. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

E. The statement is true for mitosis and meiosis II

Several organisms, primarily Protists, have what are called intermediate mitotic organization. What is the most probable hypothesis about these intermediate forms of cell division? A) They represent a form of cell reproduction which must have evolved completely separately from those of other organisms. B) They demonstrate that these species are not closely related to any of the other Protists and may well be a different Kingdom. C) They rely on totally different proteins for the processes they undergo. D) They may be more closely related to plant forms that also have unusual mitosis. E) They show some of the evolutionary steps toward complete mitosis but not all.

E. They show some of the evolutionary steps toward complete mitosis but not all

I. Prophase II. Metaphase I III. Anaphase I IV. Telophase I IV. Prophase II VI. Metaphase II VII. Anaphase II VIII. Telophase II Centromeres of sister chromatids disjoin and chromatids separate. A) II B) III C) IV D) V E) VII

E. VII

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents? A) XcXc and XcY B) XcXc and XCY C) XCXC and XcY D) XCXC and XCY E) XCXc and XCY

E. XCXc and XCY

What is the chromosomal system for sex determination in birds? A) Haploid-diploid B) X-0 C) X-X D) X-Y E) Z-W

E. Z-W

Which of the following two genes are closest on a genetic map of Drosophila? A) b and vg B) vg and cn C) rb and cn D) cn and b E) b and rb

E. b and rb

In 1981, a stray black cat with unusual rounded, curled-back ears was adopted by a family in California. Hundreds of descendants of the cat have since been born, and cat fanciers hope to develop the curl cat into a show breed. Suppose you owned the first curl cat and wanted to develop a true-breeding variety. How would you determine whether the curl allele is dominant or recessive? How would you obtain true-breeding curl cats? How could you be sure they are true-breeding?

Matings of the original mutant cat with true-breeding noncurl cats will produce both curl and noncurl F1 offspring if the curl allele is dominant, but only noncurl offspring if the curl allele is recessive. You would obtain some true-breeding offspring homozygous for the curl allele from matings between the F 1 cats resulting from the original curl × noncurl crosses whether the curl trait is dominant or recessive. You know that cats are true-breeding when curl × curl matings produce only curl offspring. As it turns out, the allele that causes curled ears is dominant.

Pseudohypertrophic muscular dystrophy is an inherited disorder that causes gradual deterioration of the muscles. It is seen almost exclusively in boys born to apparently normal parents and usually results in death in the early teens. Is this disorder caused by a dominant or a recessive allele? Is its inheritance sex-linked or autosomal? How do you know? Explain why this disorder is almost never seen in girls.

Recessive; if the disorder were dominant, it would affect at least one parent of a child born with the disorder. The disorderʹs inheritance is sex-linked because it is seen only in boys. For a girl to have the disorder, she would have to inherit recessive alleles from both parents. This would be very rare, since males with the recessive allele on their X chromosome die in their early teens.

Women born with an extra X chromosome (XXX) are healthy and phenotypically indistinguishable from normal XX women. What is a likely explanation for this finding? How could you test this explanation?

The inactivation of two X chromosomes in XXX women would leave them with one genetically active X, as in women with the normal number of chromosomes. Microscopy should reveal two Barr bodies in XXX women.

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