Ch 10

Drag the terms on the left to the appropriate blanks in the sentences on the right. 1. Chromosome pairs of the same length and centromere location are called ___ 2. Replicated forms of a chromosome are called ___ 3. Crossing over occurs between the ___ of homologous chromosomes early in meiosis I. 4. Chromosomes that differ in length and centromere location are called ___.

1. homologous chromosomes. 2. sister chromatids. 3. nonsister chromatids 4. non-homologous chromosomes.

Drag the words on the left to the appropriate blanks to complete the sentences on the right. 1. During ___, pairs of homologous chromosomes align in the center of the cell. 2. During ___, the separated chromatids elongate and (usually) cytokinesis occurs, forming four genetically distinct haploid daughter cells 3. During ___, homologous chromosomes separate by moving with the spindle microtubules toward the poles. 4. During ___, a spindle apparatus forms and individual chromosomes (each composed of sister chromatids) begin to move toward the center of the cell. 5. During ___, chiasmata form and crossing-over occurs. 6. During ___, sister chromatids separate and move toward the poles. 7. During ___, the separated chromosomes cluster at the poles and cytokinesis occurs, forming two daughter cells, each with a haploid set of replicated chromosomes. 8. During ____, individual chromosomes (each composed of sister chromatids) align in the center of the cell.

1. metaphase I 2. telophase II 3. anaphase I 4. prophase II 5. prophase I 6. anaphase II 7. telophase I 8. metaphase II

At the end of _____ and cytokinesis there are four haploid cells. a. telophase II b. interphase c. anaphase I d. prophase I e. prophase II

a

Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?. a. meiosis b. mutation c. genetic drift d. natural selection e. mitosis

a

Heritable variation is required for which of the following? a. evolution b. the production of a clone c. meiosis d. mitosis e. asexual reproduction

a

How does mitosis affect ploidy level? If a parent cell is diploid, the daughter cells produced by mitosis are _____. a. diploid b. haploid

a

In alternation of generations, what is the diploid stage of a plant that follows fertilization called? a. sporophyte b. karyotype c. spore d. gametophyte e. chiasmata

a

Normal human gametes carry _____ chromosomes. a. 23 b. 5 c. 46 pairs of d. 23 pairs of e. 46

a

What is the term for the original chromosome and its exact copy? a. sister chromatids b. nonsister chromatids c. centromeres d. homologous chromosomes

a

Which statement correctly describes a key difference between cells entering prophase of mitosis versus prophase I of meiosis? a. For cells entering mitosis, homologous chromosomes function independently; for cells entering meiosis, homologous chromosomes pair up. b. Cells entering meiosis contain twice as much DNA as cells entering mitosis, which is essential because meiosis involves two cell divisions. c. DNA replication before mitosis produces sister chromatids, whereas DNA replication before meiosis produces homologous chromosomes.

a

Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II? a. DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. b. DNA content is halved only in meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. c. DNA content is halved only in meiosis I. Ploidy level changes from diploid to haploid only in meiosis II. d. DNA content is halved only in meiosis I. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. e. DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid only in meiosis II.

a

Which of the following statements is/are true about the process of fertilization? Select all that apply. a. The process of fertilization ensures that an organism receives a complete chromosome set from both its mother and its father. b. In sexually reproducing organisms, the number of chromosome sets (which is halved during meiosis) doubles at fertilization. c. The process of fertilization is random, meaning that any of the possible male gametes can fuse with any of the possible female gametes, resulting in a zygote with a unique combination of genes. d. Fertilization is the fusion of a haploid male gamete and a haploid female gamete to produce a diploid zygote.

a,b,c,d

Which processes lead to most genetic variation in sexually reproducing organisms? a. random fertilization b. independent assortment of chromosomes in meiosis c. cytokinesis d. crossing over

a,b,d

Identify all possible products of meiosis in plant and animal life cycles. a. Gametes (sperm and eggs) b. Multicellular adult organisms c. Spores

a,c

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply. a. The two daughter cells produced in meiosis I would be identical. b. There would be less genetic variation among gametes. c. The daughter cells of meiosis I would be diploid, but the daughter cells of meiosis II would be haploid. d. The four daughter cells produced in meiosis II would all be different. e. Independent assortment of chromosomes would not occur. f. The two sister chromatids of each replicated chromosome would no longer be identical.

b

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids. a. telophase b. telophase I c. telophase II d. interphase e. metaphase II

b

How are sister chromatids and homologous chromosomes different from each other? a. They are not different. Homologous chromosomes and sister chromatids are both identical copies of each other. b. Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. c. Homologous chromosomes are identical copies of each other. One sister chromatid comes from the father, and one comes from the mother. d. Homologous chromosomes are closely associated with each other in both mitosis and meiosis. Sister chromatids are only associated with each other during mitosis. e. Sister chromatids are only formed during mitosis. Homologous chromosomes are formed during meiosis.

b

Select the statement that accurately describes gametes. a. Gametes, such as eggs or sperm, are diploid reproductive cells that are produced in asexual life cycles. b. Gametes, such as eggs and sperm, are haploid reproductive cells that fuse during fertilization in sexual life cycles. c. Gametes, such as eggs and sperm, are diploid reproductive cells that are involved in both sexual and asexual life cycles.

b

Crossing over occurs at the beginning of meiosis. Which of the following statements is/are true about crossing over? Select all that apply. a. Crossing over is a rare event and can only occur at one location along each pair of homologous chromosomes. b. As a result of crossing over, the two sister chromatids of a replicated chromosome are no longer identical. c. Crossing over involves the exchange of corresponding segments of DNA between sister chromatids. d. Crossing over produces chromosomes with new combinations of maternal and paternal alleles.

b,d

A human cell containing 22 autosomes and a Y chromosome is a. an egg. b. a somatic cell of a male. c. a sperm. d. a somatic cell of a female. e. a zygote.

c

During _____ a spindle forms in a haploid cell. a. anaphase II b. prophase I c. prophase II d. telophase I and cytokinesis e. metaphase II

c

Homologous chromosomes move toward opposite poles of a dividing cell during a. binary fission b. meiosis II. c. meiosis I. d. mitosis. e. fertilization.

c

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 II would be a. 0.25x. b. 0.5x. c. x. d. 2x. e. 4x

c

Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct? a. The cell that contains these sister chromatids must be haploid. b. These chromatids make up a diploid chromosome. c. Barring mutation, the two sister chromatids must be identical.

c

What effect do meiosis and fertilization have on the ploidy level of cells produced by each process? a. Neither meiosis nor fertilization changes the ploidy level. b. Meiosis decreases the ploidy level from 2n to n; fertilization does not change the ploidy level. c. Meiosis decreases the ploidy level from 2n to n; fertilization increases the ploidy level from n to 2n. d. Meiosis does not change the ploidy level; fertilization increases the ploidy level from n to 2n. e. Meiosis increases the ploidy level from n to 2n; fertilization decreases the ploidy level from 2n to n.

c

Which of the following occurs during meiosis but not during mitosis? a. Chromosomes align at the metaphase plate. b. Chromosomes migrate to opposite poles. c. Synapsis occurs. d. Chromosomes condense. e. A spindle apparatus forms.

c

Which statement would be true about the four daughter cells of meiosis II if crossing over occurred during meiosis I? (Hint: Think about the sister chromatids that separate at anaphase II.) a. All four daughter cells would be genetically identical. b. Two of the four daughter cells would be genetically identical to each other, while the other two daughter cells would be genetically identical to each other. c. All four daughter cells would be genetically different.

c

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes. a. 8 b. 32 c. 64 d. 16 e. 30

d

Asexual reproduction _____. a. is limited to single-cell organisms b. is limited to plants c. requires both meiosis and mitosis d. produces offspring genetically identical to the parent e. leads to a loss of genetic material

d

Crossing over is unique to meiosis. Its occurrence depends on specific events early in prophase I and it has important consequences for the rest of meiosis and beyond. Consider these statements about crossing over: 1. For crossing over to occur, homologous chromosomes must align precisely early in prophase I so that nonsister chromatids can exchange corresponding segments of DNA. 2. Crossing over occurs at the ends of chromosomes, rather than near the centromeres, because segments of DNA near the centromeres cannot break and rejoin easily. 3. As a result of crossing over, sister chromatids are no longer identical to each other. 4. Crossing over prevents homologous chromosomes from separating during meiosis I. Which of the above statements are correct? a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2, and 3 e. 1, 2, 3, and 4

d

Homologous chromosomes migrate to opposite poles during _____. a. metaphase II b. metaphase I c. prophase II d. anaphase I e. telophase II and cytokinesis

d

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

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

In terms of the behavior of the chromosomes, how does meiosis I compare to meiosis II? a. Homologous chromosomes separate in both meiosis I and meiosis II. b. Sister chromatids separate in meiosis I; homologous chromosomes separate in meiosis II. c. Sister chromatids separate in both meiosis I and meiosis II. d. Homologous chromosomes separate in meiosis I; sister chromatids separate in meiosis II.

d

Meiosis I produces _____ cells, each of which is _____. a. four ... haploid b. two... diploid c. two... identical to the other d. two ... haploid e. four ... diploid

d

Meiosis II typically produces _____ cells, each of which is _____. a. four ... identical to the other b. two ... haploid c. four ... diploid d. four ... haploid e. two... diploid

d

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells? a. four haploid cells ... two diploid cells b. two diploid cells ... two haploid cells c. two diploid cells ... two diploid cells d. two diploid cells ... four haploid cells e. four diploid cells ... four haploid cells

d

What number and types of chromosomes are found in a human somatic cell? a. 45 autosomes and 1 sex chromosome b. 22 autosomes and 1 sex chromosome c. n chromosomes d. 44 autosomes and 2 sex chromosomes e. 21 autosomes and 2 sex chromosomes

d

Complete this statement for a diploid organism in which n = 6. Before a cell in this organism undergoes meiosis, the cell has _____ chromosomes. The daughter cells of meiosis I will have _____ chromosomes; the daughter cells of meiosis II will have _____ chromosomes. a. 6/3/3 b. 12/12/6 c. 12/6/3 d. 6/6/3 e. 12/6/6

e

During _____ chromosomes align single file along the equator of a haploid cell. a. anaphase I b. metaphase I c. prophase I d. telophase I and cytokinesis e. metaphase II

e

During _____ sister chromatids separate. a. metaphase I b. prophase I c. interphase d. prophase II e. anaphase II

e

For what purpose(s) might a karyotype be prepared? Choose the best answer. a. for prenatal screening, to determine if a fetus has the correct number of chromosomes b. to determine whether a fetus is male or female c. to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations d. The first and second answers are correct. e. The first three answers are correct.

e

Human gametes are produced by _____. a. fertilization b. asexual reproduction c. the cell cycle d. mitosis e. meiosis

e

Synapsis occurs during _____. a. metaphase II b. prophase II c. anaphase II d. telophase I and cytogenesis e. prophase I

e

What is crossing over? a. also referred to as the "independent assortment of chromosomes" b. a direct consequence of the separation of sister chromatids c. the movement of genetic material from one chromosome to a nonhomologous chromosome d. making an RNA copy of a DNA strand e. the exchange of homologous portions of nonsister chromatids

e

Can you rank the size of three DNA-containing structures? Rank these DNA-containing structures from largest to smallest gene genome chromosome

largest- genome, chromosome, gene