Chapter 7

Accidents during meiosis that can result in trisomies and monosomies are called a. nondisjunctions. b. inversions. c. reciprocal translocations. d. recombinations. e. acrocentricities.

a

Which of the following statements regarding tumor suppressor drugs and drugs developed to treat cancers resulting from oncogenes is true? a. Tumor suppressors need to be reactivated, whereas oncogenes need to be switched off. b. Tumor suppressors need to be switched off, whereas oncogenes need to be switched on. c. Both tumor suppressors and oncogenes need to be switched off. d. Both tumor suppressors and oncogenes need to be switched on. e. None of the above

a

Knowledge of the cell cycle has led to improved means of treating cancer. The drug 5-fluorouracil, which blocks the synthesis of thymine, inhibits the cell cycle at the end of a. G1. b. G2. c. S. d. prophase. e. metaphase.

b

One-fourth of all human breast cancer cells have been found to have an increased amount of the oncogene a. P21. b. HER2. c. Cdk. d. Cyclin. e. RB.

b

Which illustration best represents the chromosomal makeup of a daughter cell after successful mitosis and cytokinesis? a. A b. B c. C d. None of the above

b

Which illustration best represents the chromosomal makeup of a parent cell in G1? a. A b. B c. C d. None of the above

b

The DNA content of an individual cell can be measured by applying a DNA-specific dye to the cell and then passing it through an instrument that measures the staining intensity (higher intensity = more DNA present). Suppose that a new drug (which kills cells during a particular stage of the cell cycle) has been tested on a population of rapidly dividing tumor cells. The DNA content of the cells is analyzed and then compared with those of untreated cells, with the results shown below. This new drug is most likely inhibiting which stage of the cell cycle?a. Meiosis b. Gap 1 c. Synthesis d. Mitosis e. There is not enough information to make a prediction.

c

The cell is most likely in which phase.a. Metaphase of mitosis b. Anaphase of mitosis c. Metaphase I of meiosis d. Metaphase II of meiosis e. Anaphase I of meiosis

c

Which illustration best represents the chromosomal makeup of a parent cell immediately prior to mitotic prophase? a. A b. B c. C d. None of the above

c

Which cell structure is indicated by the two leaders?a. Chromosome b. Centromere c. Chromatid d. Kinetochore microtubule e. Centrioles

d

Which of the following are illustrated in this diagram? a. Two chiasmata, two daughter chromosomes, and prophase of mitosis b. Three chiasmata, two sister chromatids, and prophase I of meiosis c. Two chiasmata, two nonhomologous chromatids, and prophase II of meiosis d. Two chiasmata, two pairs of homologous chromatids, and prophase I of meiosis e. Three chiasmata, two daughter chromosomes, and prophase I of meiosis

d

In a particular type of tissue, 75 percent of cells are found in G1, past the restriction point (R). The tissue has become cancerous, and 81 percent of the cancer cells are in G2. If the complete cell cycle of a cancer cell and a normal cell lasts one week, which of the following would be the best drug strategy to eliminate the cancer cells? a. Blocking the DNA synthesis process for eight days b. Preventing the transition from G2 to mitosis for eight days c. Preventing normal function of the mitotic spindle for eight days d. Both a and b e. Both b and c

e

At the milestone that defines telophase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up. e. cross over

c

The mitotic spindle is composed of a. chromosomes. b. chromatids. c. microtubules. d. chromatin. e. centrosomes

c

When cyclin binds Cdk, a. the cell transitions from G2 to S. b. kinase activation occurs. c. chromosomes condense. d. the cell quickly enters M phase. e. the cell undergoes apoptosis.

b

At the milestone that defines anaphase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up. e. cross over.

a

Bacteria typically have _______, whereas eukaryotes have _______. a. one chromosome that is usually circular; many chromosomes that are linear b. several chromosomes that are circular; many chromosomes that are linear c. one chromosome that is linear; many chromosomes that are circular d. two chromosomes that are usually circular; eight chromosomes that are linear e. None of the above

a

Chromosomes "decondense" into diffuse chromatin a. at the end of telophase. b. at the beginning of prophase. c. at the end of interphase. d. at the end of metaphase. e. only in dying cells.

a

During mitosis and meiosis the chromatin condenses. Which of the following processes takes place more easily because of this compaction? a. The orderly distribution of genetic material to two new nuclei b. The replication of the DNA c. Exposing the genetic information on the DNA d. The unwinding of DNA from around the proteins e. The disappearance of the nuclear membrane

a

Genetic recombination occurs during a. prophase of meiosis I. b. the interphase preceding meiosis II. c. the mitotic telophase. d. fertilization. e. the formation of somatic cells.

a

How does a nucleus in G2 differ from a nucleus in G1? a. The G2 nucleus has twice the amount of DNA as the G1 nucleus. b. DNA synthesis occurs only in G1 phase. c. Inactive cells are arrested only in G2 phase. d. During G2, the cell prepares for S phase. e. All of the above

a

Mature nerve cells, which are incapable of cell division, are most likely in a. G1. b. S phase. c. G2. d. mitosis. e. meiosis.

a

Meiosis can occur a. in all sexually reproducing organisms. b. only when an organism is diploid. c. only in multicellular organisms. d. only in haploid organisms. e. only in single-celled organisms.

a

The DNA of a eukaryotic cell is a. double-stranded. b. single-stranded. c. circular. d. complex inverted. e. conservative

a

The distribution of mitochondria between the daughter cells during cytokinesis a. is random. b. is directed by the mitotic spindle. c. is directed by the centrioles. d. results in the mitochondria remaining in the parent cell. e. occurs only during meiosis

a

The fact that most monosomies and trisomies are lethal to human embryos illustrates the a. importance of the orderly distribution of genetic material during meiosis. b. exchange of genetic information during crossing over. c. advantage of sexual reproduction to the survival of a population. d. fact that each chromosome contains a single molecule of DNA. e. formation of haploid gametes as a result of meiosis.

a

The members of a homologous pair of chromosomes a. are identical in size and appearance. b. contain identical genetic information. c. separate to opposite poles of the cell during mitosis. d. are found only in haploid cells. e. are present only after the S phase.

a

The microtubules of the mitotic spindle attach to a specialized structure in the centromere region of each chromosome called the a. kinetochore. b. nucleosome. c. equatorial plate. d. aster. e. centrosome.

a

Very few chromosome abnormalities (trisomies and monosomies) are observed in the human population because a. they are usually lethal and often cause spontaneous abortion of the embryo. b. they are lethal in early childhood. c. meiosis distributes chromosomes to daughter cells with great precision. d. individuals with these abnormalities are hard to distinguish from the general population. e. the human meiotic spindle is self-correcting.

a

Which occurs right after cytokinesis? a. G1 b. S phase c. G2 d. M phase e. Interphase

a

Which of the following is an indicator of programmed cell death? a. Fragmented chromatin b. Swelling of the membrane c. Cell lysis d. Loss of transcription control e. All of the above

a

Which of the following pairs of phase and event does not match? a. Prophase: Duplication of centrosome b. Metaphase: Formation of equatorial plate c. Telophase: Formation of nuclear envelopes d. Interphase: Replication of DNA e. Anaphase: Separation of chromatids

a

Which of the following phases of the cell cycle is/are not part of interphase? a. M b. S c. G1 d. G2 e. Both a and b

a

Which of the following statements about homologous chromosome pairs is false? a. They come from only one of the individual's parents. b. They usually contain slightly different versions of the same genetic information. c. They separate from each other during meiosis I. d. They synapse during meiosis I. e. Each contains two sister chromatids at the beginning of meiosis I.

a

Which of the following is not part of sexual reproduction? a. The segregation of homologous chromosomes during gamete formation b. The fusion of sister chromatids during fertilization c. The fusion of haploid cells from a diploid zygote d. The reduction in chromosome number during meiosis e. The production of genetically distinct gametes during meiosis

b

A haploid cell is a cell a. in which the genes are arranged haphazardly. b. containing only one copy of each chromosome. c. that has resulted from the process of mitosis. d. with twice the number of chromosomes of a diploid cell. e. None of the above

b

A potato has a diploid number of 48. If an egg of this plant is found to have 23 chromosomes, the most likely explanation is that a. normal meiosis has occurred. b. nondisjunction occurred during meiosis I. c. normal mitosis has occurred. d. nondisjunction occurred during mitosis. e. crossing over occurred during meiosis I.

b

A triploid nucleus cannot undergo meiosis because a. the DNA cannot replicate. b. not all of the chromosomes can form homologous pairs. c. the sister chromatids cannot separate. d. cytokinesis cannot occur. e. a cell plate cannot form.

b

A triploid plant has a. one extra chromosome. b. one extra set of chromosomes. c. three chromosomes. d. three times the chance of surviving that a monoploid has. e. None of the above

b

All zygotes are a. multicellular. b. diploid. c. animals. d. clones. e. gametes

b

Cells that do not divide are usually arrested in a. S. b. G1. c. G2. d. M. e. prophase.

b

Down syndrome is diagnosed by means of an examination of the individual's a. spores. b. karyotype. c. chromatin. d. nucleosomes. e. kinetochores.

b

During meiosis I in humans, one of the daughter cells receives a. only maternal chromosomes. b. a mixture of maternal and paternal chromosomes. c. the same number of chromosomes as that of a diploid cell. d. a sister chromatid from each chromosome. e. one-fourth the amount of DNA in the parent nucleus

b

During meiosis, the sister chromatids separate during a. anaphase I. b. anaphase II. c. the S phase. d. synapsis. e. telophase II.

b

During mitotic anaphase, chromosomes migrate a. from the poles of the cell toward the equatorial plate. b. from the equatorial plate toward the poles. c. toward the nuclear envelope. d. along with their sister chromatids toward one pole. e. along with the other member of the homologous pair toward the equatorial plate

b

Each diploid cell of a human female contains how many of each type of chromosome? a. 1 b. 2 c. 4 d. 23 e. 46

b

In a haploid organism, most mitosis occurs a. after fertilization and before meiosis. b. after meiosis and before fertilization. c. between meiosis I and II. d. during G1. e. in diploid cells.

b

Replication of DNA occurs during which phase? a. G1 b. S phase c. G2 d. M phase e. Interphase

b

The initiation of the S phase of the cell cycle depends on a pair of molecules called _______ and _______. a. actin; myosin b. Cdk's; cyclin c. ligand; receptor d. MSH; MSH-receptor e. ATP; ATPase

b

The molecules that make up a chromosome are _______ and _______. a. DNA; RNA b. DNA; proteins c. proteins; lipids d. nucleotides; nucleosides e. proteins; phospholipids

b

The number of chromosomes is reduced to half during a. anaphase of mitosis and meiosis. b. meiosis I. c. meiosis II. d. fertilization. e. interphase.

b

The structures that line up the chromatids on the equatorial plate during metaphase are called a. asters. b. polar and kinetochore microtubules. c. centrosomes. d. centrioles. e. poles.

b

The total DNA content of each daughter cell is reduced during meiosis because a. chromosomes do not replicate during the interphase preceding meiosis I. b. chromosomes do not replicate between meiosis I and II. c. half of the chromosomes from each gamete are lost during fertilization. d. sister chromatids separate during anaphase of meiosis I. e. chromosome arms are lost during crossing over.

b

Asexual reproduction produces genetically identical individuals because a. chromosomes do not have to replicate during asexual reproduction. b. it involves chromosome replication without cytokinesis. c. no meiosis or fertilization takes place. d. cell division occurs only in meiosis. e. the mitotic spindle prevents nondisjunction.

c

Cells in the intestinal epithelium divide continuously so that cells lost from the surface of the intestinal lining are replaced. A microscopic examination of the live cells would show that most of them a. are in meiosis. b. are in mitosis. c. are in interphase. d. have condensed chromatin. e. Both b and d

c

Chronic neurodegenerative diseases like Huntington's disease involve the death of neurons in certain parts of the brain. Progress in treating such diseases will likely come about when medical science has a better understanding of which of the following? a. The process of necrosis b. Oncogenes c. Caspases d. Tumor suppressors e. Cyclin-dependent

c

Cyclin-dependent kinases (Cdk's) catalyze the phosphorylation of targeted proteins. Which of the following statements about this process is true? a. It decreases the mass of the proteins. b. It makes the targeted proteins hydrophobic. c. It changes the shape and function of the targeted proteins. d. It gives the proteins a three-dimensional shape. e. It blocks the cell cycle from proceeding

c

Diploid cells of the fruit fly Drosophila have ten chromosomes. How many chromosomes does a Drosophila gamete have? a. 1 b. 2 c. 5 d. 10 e. 20

c

During asexual reproduction, the genetic material of the parent is passed on to the offspring by a. homologous pairing. b. meiosis and fertilization. c. mitosis and cytokinesis. d. karyotyping. e. chiasmata.

c

In a female animal with a diploid chromosome number of 12, half of the egg cells are found to have five chromosomes. The most probable explanation is a. normal mitosis. b. normal meiosis. c. nondisjunction in meiosis I. d. nondisjunction in meiosis I or II. e. nondisjunction in mitosis.

c

In organisms that display alternation of generations, a. only gametes are haploid. b. only zygotes are diploid. c. gametophytes are haploid and zygotes are diploid. d. Both a and b e. Both b and c

c

One difference between mitosis and meiosis I is that a. homologous chromosome pairs synapse during mitosis. b. chromosomes do not replicate in the interphase preceding meiosis. c. homologous chromosome pairs synapse during meiosis but not during mitosis. d. spindles composed of microtubules are not required during meiosis. e. sister chromatids separate during meiosis but not during mitosis.

c

The exchange of genetic material between chromatids on homologous chromosomes occurs during a. interphase. b. mitosis and meiosis. c. prophase I. d. anaphase I. e. anaphase II.

c

The number of daughter chromosomes in a human cell (diploid number 46) in anaphase II of meiosis is a. 2. b. 23. c. 46. d. 69. e. 92.

c

The process of programmed cell death is called a. necrosis. b. lysis. c. apoptosis. d. cell displacement. e. cellular suicide.

c

The uncondensed length of human DNA found in chromosomes is _______, whereas a typical cell is 10 µm in length. a. 5 μm b. 2 μm c. 2 meters d. 20 meters e. 2.54 inches

c

When dividing cells are examined under a light microscope, chromosomes first become visible during a. interphase. b. the S phase. c. prophase. d. G1. e. G2

c

Which occurs right before prophase? a. G1 b. S phase c. G2 d. M phase e. Interphase

c

Which of the following correctly distinguishes kinetochore microtubules from polar microtubules? a. Kinetochore microtubules are replaced by polar microtubules when the chromatids move toward the poles. b. Only polar microtubules contain cytoplasmic dynein, which acts as a "molecular motor." c. Kinetochore microtubules attach to the chromosomes, whereas polar microtubules extend from one pole to the other. d. Kinetochore microtubules form before polar microtubules. e. There is no difference; they are both names for the same structure.

c

Which of the following processes increases the genetic diversity of offspring? a. Mitosis b. Cloning c. Sexual reproduction d. Cytokinesis e. Fission

c

Which of the following statements about necrosis is true? a. It requires ATP. b. It does not cause inflammation. c. It may occur when cells are damaged by toxins. d. It produces nucleosome-sized pieces of chromatin. e. It results in fragmentation of the cell.

c

A bacterial cell gives rise to two genetically identical daughter cells by a process known as a. nondisjunction. b. mitosis. c. meiosis. d. binary fission. e. fertilization.

d

A diploid human cell normally has 23 pairs of homologous chromosomes, but as a woman ages, the chances of nondisjunction increase. Imagine that a gamete is produced in which the two homologues of chromosome 21 have failed to separate. If the gamete is fertilized with a normal sperm, the embryo's cells will contain _______ chromosomes. a. 23 b. 24 c. 46 d. 45 e. 48

d

A typical eukaryotic cell cycle consists of a. mitosis and meiosis. b. G1, the S phase, and G2. c. prophase, metaphase, anaphase, and telophase. d. interphase, mitosis, and cytokinesis. e. meiosis and fertilization.

d

At the end of the first meiotic division, each chromosome consists of a. chiasmata. b. a homologous chromosome pair. c. four copies of each DNA molecule. d. two chromatids. e. a pair of polar microtubules

d

At the milestone that defines metaphase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up at the equatorial plate. e. cross over.

d

Chromatin condenses to form discrete, visible chromosomes a. early in G1. b. during S. c. during telophase. d. during prophase. e. at the end of cytokinesis.

d

Chromosome number is reduced during meiosis because the process consists of a. two cell divisions without any chromosome replication. b. a single cell division without any chromosome replication. c. two cell divisions in which half of the chromosomes are destroyed. d. two cell divisions and only a single round of chromosome replication. e. four cell divisions with no chromosome replication.

d

Cytokinesis occurs during which phase? a. G1 b. S phase c. G2 d. M phase e. Interphase

d

DNA replication occurs a. during both mitosis and meiosis. b. only during mitosis. c. only during meiosis. d. during S phase. e. during G2 phase.

d

During bacterial cell division, the single cell is separated into two cells by a. centrosomes. b. spindle fibers. c. nucleosomes. d. pinching of the plasma membrane. e. aneuploidy.

d

During prokaryotic cell division, two chromosomes separate from each other and are distributed into the daughter cells by a. attaching themselves to microtubules. b. a mitotic spindle. c. repellent forces. d. the attaching of ori to a protein filament. e. All of the above

d

In an organism with a diploid number of 8, a gamete has _______ chromosomes, a liver cell has _______ chromosomes, and a sperm cell at meiotic anaphase I has _______ chromosomes. a. 8; 8; 8 b. 8; 4; 8 c. 8; 4; 4 d. 4; 8; 8 e. 4; 4; 4

d

In an organism with a haploid number of 9, a skin cell has _______ chromosomes, a sperm cell at meiotic anaphase II has _______ chromosomes, and a newly formed zygote has _______ chromosomes. a. 18; 18; 18 b. 9; 9; 9 c. 9; 18; 9 d. 18; 9; 9 e. 18; 9; 18

d

In plant cells, cytokinesis is accomplished by the formation of a(n) a. aster. b. membrane furrow. c. equatorial plate. d. cell plate. e. spindle.

d

In which of the following would you expect to find multicellular individuals with a ploidy value of "n"? a. Bread mold b. Pine trees c. Rabbits d. Both a and b e. Both b and c

d

Regulation of the cell cycle is dependent on cyclins and cyclin-dependent kinases. A cell's capacity to progress beyond the restriction point is dependent on which of the following? a. Cdk and cyclin B b. Cyclin D and p21 c. Cyclin A and Cdk d. Phosphorylation of RB by Cdk e. External signals from growth factors

d

Segregation of DNA occurs during which phase? a. G1 b. S phase c. G2 d. M phase e. Interphase

d

Sexual reproduction increases genetic variability through a. the exchange of genetic information between male and female gametes during meiosis I. b. the random separation of homologous chromosomes. c. the union of male and female gametes. d. crossing over, independent assortment, and random fertilization. e. random assortment of male and female chromosomes.

d

The second division of meiosis a. returns the chromosome number before fertilization to diploid. b. allows for crossing over and random distribution of chromosomes. c. reduces cell size by dividing the cytoplasm in half. d. prevents a doubling of chromosome copies at fertilization. e. is required in order for fertilization to occur.

d

Which of the following does not occur during mitotic prometaphase? a. Disappearance of the nuclear envelope b. Initial movement of chromosomes toward the equatorial plate c. Adhesion of chromatids at the centromere d. Synapsis of homologous chromosomes e. Disappearance of the nuclei

d

Which of the following is not involved in the separation of paired chromatids and their movement to opposite poles? a. ATP is hydrolyzed by cytoplasmic dynein. b. Kinetochore microtubules shorten. c. Kinetochore microtubules pull the chromatids away from the equatorial plate. d. Polar microtubules push the chromatids to the poles. e. All of the above are involved in this phase.

d

Which of the following statements about mitosis is true? a. The chromosome number in the resulting cells is halved. b. DNA replication is completed in prophase. c. Crossing over occurs during prophase. d. Two genetically identical daughter cells are formed. e. It consists of two nuclear divisions.

d

Which of the following statements about plant cytokinesis is true? a. It begins when telophase ends. b. A division furrow completely separates the cytoplasm. c. It is under the control of Ca2+. d. Vesicles fuse to form a cell plate. e. The spindle fibers break down to form a cell plate.

d

Which of the following statements about sister chromatids is false? a. They arise by replication during S phase. b. They separate from each other during each mitotic anaphase. c. They usually contain identical versions of the same genetic information. d. They separate from each other during meiosis I. e. They are joined during prophase I and metaphase I at their common centromere.

d

Which of the following types of organisms readily undergo "cloning" naturally? a. Plants b. Bacteria c. Mammals d. Both a and b e. All of the above

d

After the centromeres separate during mitosis, the chromatids, now called _______, move toward opposite poles of the spindle. a. centrosomes b. kinetochores c. half-spindles d. asters e. daughter chromosomes

e

Centrosomes a. are constricted regions of phase chromosomes. b. are part of cilia. c. are the central region of the cell. d. are the region where the membrane constricts during cytokinesis. e. determine the plane of cell division.

e

For a prokaryote cell to divide, which of the following must occur? a. DNA replication, segregation of DNA, and cytokinesis b. DNA replication, crossing over, and segregation of DNA c. DNA replication and segregation of DNA d. Cell growth and cytokinesis e. A reproductive signal, DNA replication, segregation, and cytokinesis

e

How does mitotic prophase differ from prophase I of meiosis? a. Chromatin supercoils only in mitotic prophase. b. The nuclear envelope disappears only in prophase I of meiosis. c. Synapsis occurs in mitotic prophase and but not in meiotic prophase I. d. The chromatids separate in mitotic prophase but not in prophase I of meiosis. e. Crossing over is characteristic of prophase I of meiosis but not of mitotic prophase.

e

In all sexually reproducing organisms, the diploid phase of the life cycle begins at a. spore formation. b. gamete formation. c. meiosis. d. mitosis. e. fertilization

e

Includes the G1 and G2 phases a. G1 b. S phase c. G2 d. M phase e. Interphase

e

Microtubules that form the mitotic spindle tend to originate from or terminate in a. centromeres and telomeres. b. euchromatin. c. centrioles and telomeres. d. the nuclear envelope. e. centrioles and kinetochores.

e

The energy to move chromosomes during mitosis is provided by a. centrioles. b. DNA polymerization. c. migration of the centrosomes. d. formation of the cell plate. e. ATP.

e

The event in the cell division process that clearly involves microfilaments is a. chromosome separation during anaphase. b. movement of chromosomes to the metaphase plate. c. chromosome condensation during prophase. d. disappearance of the nuclear envelope during prophase. e. cytokinesis in animal cells.

e

The four haploid nuclei found at the end of meiosis differ from one another in their exact genetic composition. Some of this difference is the result of a. cytokinesis. b. replication of DNA during the S phase. c. separation of sister chromatids at anaphase II. d. spindle formation. e. crossing over during prophase I.

e

The major drawback of asexual reproduction is that it a. takes a great deal of time. b. generates variation. c. prevents change. d. requires cytokinesis. e. produces less variation among offspring compared to sexual reproduction.

e

The processes of synapsis and the formation of chiasmata a. involve reciprocal exchange of chromosomal sections. b. involve the recombination of DNA on homologous chromosomes. c. bring about an increase in genetic variation. d. provide evidence that an exchange of genetic material has occurred. e. All of the above

e

The products of mitosis are a. one nucleus containing twice as much DNA as the parent nucleus. b. two genetically identical cells. c. four nuclei containing half as much DNA as the parent nucleus. d. four genetically identical nuclei. e. two genetically identical nuclei

e

Which of the following statements about cervical cancer, a relatively common cancer, is false? a. It can be detected early by a PAP test. b. It is usually caused by human papillomavirus (HPV). c. It infects the cervical cells with viral DNA. d. The HPV that infects cervical tissue spreads by sexual transmission. e. It is never fatal.

e

Which of the following statements about sexual and asexual reproduction is true? a. Haplontic organisms reproduce asexually. b. Sexual reproduction always involves the fertilization of eggs by sperm. c. An organism can only reproduce either sexually or asexually. d. Both a and c e. None of the above

e