Chapter 7

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.

Chromosome movement during anaphase is the result of all of the following except a. the hydrolysis of ATP by motor proteins (dynein). b. molecular motors at the kinetochores that move the chromosomes toward the poles. c. molecular motors at the centrosome that pull the microtubules toward the poles. d. shortening of the microtubules at the centrosome that pull the chromosomes toward the poles. e. the generation of ATP.

Chromosomes are becoming condensed in this stage of mitosis. Which stage of the cell cycle is this? a. M phase b. S phase c. Prophase d. Anaphase e. Telophase

A bacterial colony grows steadily due to rapid cell division in a medium that is rich in the amino acid alanine. If the alanine concentration drops, cell division slows. Supplying more alanine results in resumed cell division. Alanine is thus a. a fertilization signal. b. a ter site. c. a reproductive signal. d. an oncogene. e. an ori signal.

After DNA replication, each chromosome has _______ molecules of DNA called _______, that after separation are known as _______ chromosomes. a. two; sister chromatids; daughter b. four; sister chromatids; daughter c. two; daughter chromatids; sister d. four; sister chromosomes; daughter e. two; daughter chromosomes; sister

Suppose that in mitotic metaphase, there are 16 sister chromatids in a cell. How many centromeres are in the cell? a. 1 b. 2 c. 8 d. 16 e. 32

Crossing over between non-homologous chromosomes during meiosis I will most likely result in a. nondisjunction. b. triploidy. c. trisomy d. translocation. e. monosomy.

Having extra copies of one chromosome in a cell is an example of a. allopolyploidy. b. autopolyploidy. c. disjunction. d. crossing over. e. aneuploidy.

Which structure(s) is/are primarily involved in determining the direction of movement of sister chromatids during mitosis? a. Kinetochores b. Chromatin c. Chiasma d. Centrosomes e. Cohesin

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

Which statement about reproduction is false? a. Most single-celled prokaryotes reproduce sexually. b. Some multicellular plants reproduce asexually. c. Some multicellular plants reproduce sexually. d. Most multicellular animals reproduce sexually.

Which of the following statements about independent assortment is false? a. It generates genetic variation. b. It requires chiasmata. c. Chance determines which member of a homologous pair goes to each daughter cell. d. It occurs in meiosis but not mitosis.

The haploid chromosome number of a cell is 32. How many chromosomes will a trisomic individual have? a. 31 b. 32 c. 63 d. 65 e. 96

The haploid number of chromosomes in a cell of a grasshopper is 18. How many chromosomes are in a somatic cell? a. 9 b. 18 c. 27 d. 36 e. 72

Which statement about mitosis is false? a. It is followed by cytokinesis. b. DNA replication is completed prior to the beginning of this phase. c. The chromosome number of the resulting cells is the same as that of the parent cell. d. The daughter cells are usually genetically identical to the parental cell. e. Homologous chromosomes align at the equatorial plate.

Which of the processes below would likely produce progeny with the greatest genetic variation? a. Binary fission b. Mitosis c. Asexual reproduction d. Cloning e. Meiosis

Imagine that there is a mutation in the cyclin gene such that its gene product is nonfunctional. What kind of effect would this mutation have on a skin cell in the area of a cut? a. CDK would not be synthesized. b. There would be no effect, because skin cells do not replicate. c. The cell would be stuck in S phase and unable to replicate. d. The cell would not be able to enter G1. e. The cell would be unable to reproduce itself.

Binary fission differs from the division of eukaryotic cells in that a. binary fission results in daughter cells with differing genetic makeup. b. DNA replication does not take place in eukaryotic cells. c. a spindle is involved in chromosome segregation in eukaryotic cells. d. cytokinesis occurs only in binary fission. e. tubulin is involved in chromosome segregation in binary fission.

Pairing of homologous chromosomes occurs a. in mitosis. b. in meiosis I only. c. in meiosis II only. d. in both meiosis I and meiosis II. e. at no time.

A tissue in a plant contains three types of cells that divide at different rates. You would expect the cell type that divides most rapidly to spend _______ time in the _______ phase than the other cells. a. more; G1 b. more; G2 c. more; S d. less; G1 e. less; G2

Which cellular event occurs outside of interphase? a. DNA replication b. The synthesis of cellular components necessary for mitosis c. G1 d. The condensation of chromatin e. G2

Which statement about the mitotic spindle is true? a. It is composed of polar and kinetochore microtubules, both of which attach to chromosomes. b. It is composed of actin and myosin microfilaments. c. It is composed of kinetochores at the metaphase plate. d. It is composed of microtubules, which help separate the chromosomes to opposite poles of the cell.

A human cell in G1 of the cell cycle has 23 pairs of chromosomes. The number of daughter chromosomes in a cell in telophase II of meiosis is a. 23. b. 34. c. 46. d. 69. e. 92.

As a result of fertilization, the number of chromosomes in the zygote _______ in comparison to that in each of the gametes. a. stays the same in plants and animals b. doubles in plants and animals c. is reduced by a factor of two in plants and animals d. is reduced by a factor of three in plants and animals e. doubles in plants but stays the same in animals

Which statement about aneuploidy is false? a. It results from chromosomal nondisjunction. b. It occurs in humans. c. An individual with an extra chromosome is trisomic. d. Aneuploidy results when a piece of one chromosome translocates to another chromosome.

Which statement about chromatids is false? a. They are replicated chromosomes still joined together at the centromere. b. They are identical. c. They share one kinetochore. d. They separate during anaphase. e. They form during S phase.

An environmental change has led to the production of more than the normal amount of cyclin. This would tend to increase the activity of the CDK, leading to _______ phosphorylation of the target protein, which in turn would lead to _______ cells being stopped at the checkpoint. a. increased; more b. increased; fewer c. decreased; more d. decreased; fewer e. decreased; all

Which statement about DNA replication and cytokinesis in E. coli is true? a. DNA replication occurs in the nucleus. b. Cytokinesis is facilitated by microfilaments of actin and myosin. c. DNA replication occurs during the S phase of the cell cycle. d. Cell reproduction is initiated by reproductive signals, which lead to DNA replication, DNA segregation, and cytokinesis. e. The E. coli chromosome is linear.

Which of the following is not a feature of interphase? a. Typical cellular functions b. Cytokinesis c. DNA replication d. Preparations for mitosis e. Visible cell nucleus

What leads to recombinant chromatids? a. Nondisjunction b. Independent assortment c. Crossing over d. Aneuploidy e. Translocations

Down syndrome is an example of _______ in humans. a. monosomy b. trisomy c. translocation d. triploidy e. chiasmata

What action do CDKs perform on target proteins? a. They make allosteric changes by binding to the protein. b. They add a methyl group to the protein. c. They remove a methyl group from the protein. d. They add a phosphate group to the protein. e. They remove a phosphate group from the protein.

Which of the processes below would likely produce progeny with the greatest genetic variation? a. Binary fission b. Mitosis c. Asexual reproduction d. Cloning e. Meiosis

The essence of _______ reproduction is the random selection of half of the _______ chromosome set to make a _______ gamete. a. asexual; diploid; haploid b. asexual; haploid; diploid c. asexual; diploid; diploid d. sexual; diploid: haploid e. sexual; haploid; diplid

ytokinesis a. involves actin in both animals and plants. b. does not require energy. c. uses the same motor proteins in animals and plants d. precisely distributes organelles. e. involves the Golgi apparatus in plants.

If n = 30 for a species of beetle, then a diploid cell would have a total of _______ chromosomes. a. 1 b. 15 c. 30 d. 60 e. 90

Which statement about kinetochores on mitotic chromosomes is false? a. They are located at the centromere of each chromosome. b. They are the sites where microtubules attach to separate the chromosomes. c. They are organized so that there are two per sister chromatid. d. Kinetochore microtubules from opposite poles attach to each sister chromatid. e. They contain molecular motor proteins.

Which statement about the relationship between cyclins and CDKs is true? a. CDKs activate cyclins. b. CDKs repress cyclins. c. Cyclins activate CDKs. d. Cyclins repress CDKs. e. Cyclins and CDKs do not interact.

The haploid number of chromosomes in a cell of a grasshopper is 18. How many chromosomes are in a gamete? a. 9 b. 18 c. 27 d. 36 e. 72

Which process is closest to the opposite of meiosis in terms of effects on the number of chromosomes? a. Mitosis b. Asexual reproduction c. Alternation of generations d. Independent assortment e. Fertilization

If n is the haploid number of chromosomes, a trisomic individual has _______ chromosomes. a. n 1 b. n + 1 c. 2n 1 d. 2n + 1 e. 3n

Mutations in the hypothetical gene X can lead to cancer when they reduce the expression of the gene. Thus, X is likely a(n) a. oncogene. b. necrosis factor. c. result of aneuploidy. d. tumor suppressor. e. chiasma.

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

Apoptosis a. occurs only in animals. b. is triggered solely by signals external to the cell. c. occurs only during development. d. is the same process as necrosis. e. is controlled by signal transduction pathways.

In which of the following stages of meiosis would chiasmata be visible? a. Late prophase of meiosis I b. Interphase preceding meiosis II c. Telophase I d. Anaphase II e. Interphase preceding meiosis I

Pairing of homologous chromosomes occurs a. in mitosis. b. in meiosis I only. c. in meiosis II only. d. in both meiosis I and meiosis II. e. at no time.

Maternal chromosome 1, paternal chromosome 2, and maternal chromosome 3 go to the same pole during meiosis. This is an example of a. crossing over. b. allopolyploidy. c. autopolyploidy. d. independent assortment. e. chiasmata formation.

A chromatid is a. one-half of (one of the 2 DNA molecules) a newly replicated eukaryotic chromosome b. one of the pairs of homologous chromosomes. c. a homologous chromosome. d. a newly replicated bacterial chromosome.

Homologous chromosomes undergo crossing over during a. prophase I of mitosis. b. prophase II of meiosis. c. prophase I and II of meiosis. d. prophase I of meiosis. e. anaphase II of meiosis.

With respect to what happens with the nuclear envelope, telophase is most like the opposite of a. anaphase. b. metaphase. c. prophase. d. M phase. e. S phase.

In animals, meiosis is a. the fusion of gametes. b. a process that results in gametes. c. a type of asexual reproduction. d. the same process as mitosis. e. a process that results in somatic cells.

If greater than normal amounts of the G1 S cyclin CDK were produced, the most likely result would be _______ of RB and _______ of the cell cycle. a. more phosphorylation; acceleration b. more phosphorylation; inhibition c. less phosphorylation; inhibition d. more methylation; acceleration e. less methylation; inhibition

Binary fission differs from the division of eukaryotic cells in that a. binary fission results in daughter cells with differing genetic makeup. b. DNA replication does not take place in eukaryotic cells. c. a spindle is involved in chromosome segregation in eukaryotic cells. d. cytokinesis occurs only in binary fission. e. tubulin is involved in chromosome segregation in binary fission.

A bacterial colony grows steadily due to rapid cell division in a medium that is rich in the amino acid alanine. If the alanine concentration drops, cell division slows. Supplying more alanine results in resumed cell division. Alanine is thus a. a fertilization signal. b. a ter site. c. a reproductive signal. d. an oncogene. e. an ori signal.

The initiation of the S phase and the M phase of the cell cycle each depend on pairs of molecules called _______ and _______. a. actin; myosin b. CDKs; cyclin c. ligand; receptor d. MSH; MSH-receptor e. ATP; ATPase

In meiosis, as opposed to mitosis, a. genetically identical daughter cells are produced. b. pairing of homologous chromosomes occurs. c. crossing over cannot take place. d. there is no cytokinesis. e. only two daughter cells are formed.

A mutation causes difficulty in the separation of sister chromatids during anaphase of mitosis. Based on what you have read, the most likely cause of this phenomenon would be that a. the concentration of a CDK is too high. b. the concentration of a CDK is too low. c. cyclin levels are inappropriate. d. there is a defect in the spindle. e. there is a defect in the cell wall.

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. sister chromosomes e. daughter chromosomes

Having extra copies of one chromosome in a cell is an example of a. allopolyploidy. b. autopolyploidy. c. disjunction. d. crossing over. e. aneuploidy.

Oxygen starvation in a cell will most likely lead to a. apoptosis. b. necrosis. c. crossing over. d. independent assortment. e. the hypersensitive response.

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.