Mastering Biology Chapter 13

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?

Clone the plant.

Which of the following processes occurs when homologous chromosomes cross over in meiosis I?

Corresponding segments of non-sister chromatids are exchanged.

How are sister chromatids and homologous chromosomes different from each other? See Concept 13.3 (Page 260)

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.

Which of the life cycles is typical for plants and some algae?

II only

For the following question, match the key event of meiosis with the stages listed below.I. Prophase I V. Prophase IIII. Metaphase I VI. Metaphase IIIII. Anaphase I VII. Anaphase IIIV. Telophase I VIII. Telophase IIHomologous chromosomes are aligned at the equator of the spindle.

II. Metaphase I VI. Metaphase II

Which of the life cycles is typical for most fungi and some protists?

III only

Which of the following statements is correct in comparing sexual and asexual reproduction?

In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.

Which of the following statements is correct regarding the human Y chromosome?

It carries a gene that determines an individual's biological sex.

If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?

It has half the amount of DNA as the cell that began meiosis.

Which of the following statements is correct regarding the human X chromosomes?

It is present in every somatic cell of males and females.

During _____ a spindle forms in a haploid cell.

Prophase II

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?

The cells have half the number of chromosomes and one-fourth the amount of DNA.

Which processes lead to most genetic variation in sexually reproducing organisms?

crossing overrandom fertilizationindependent assortment of chromosomes in meiosis

Meiosis II typically produces _____ cells, each of which is _____.

four ... haploid

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I

During which of the following processes do homologous pairs of chromosomes align adjacent to one another at the metaphase plate of a cell?

metaphase I of meiosis

During _____ chromosomes align single file along the equator of a haploid cell.

metaphase II

Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes

Independent assortment of chromosomes is a result of which of the following processes?

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I Submit

Meiosis I produces _____ cells, each of which is _____.

two ... haploid

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

2x

Which of the life cycles is typical for animals?

1 only

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Consider a diploid cell where 2n = 6. During metaphase I of meiosis, as the pairs of homologous chromosomes line up on the metaphase plate, each pair may orient with its maternal or paternal homolog closer to a given pole. There are four equally probable arrangements of the homologous pairs at metaphase I. (Note that this problem assumes that no crossing over has occurred.)

1: 3,8 2: 1, 5 3: 2,6 4: 4,7

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3

Normal human gametes carry _____ chromosomes.

23

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes based on the independent assortment of chromosomes during meiosis?

About 8 Million

Meiosis guarantees that in a sexual life cycle, offspring will inherit one complete set of chromosomes (and their associated genes and traits) from each parent. The transmission of traits from parents to offspring is called heredity. Another important aspect of meiosis and the sexual life cycle is the role these processes play in contributing to genetic variation. Although offspring often resemble their parents, they are genetically different from both of their parents and from one another. The degree of variation may be tremendous. The following processes are associated with meiosis and the sexual life cycle: DNA replication before meiosis crossing over chromosome alignment in metaphase I and separation in anaphase I chromosome alignment in metaphase II and separation in anaphase II fertilization Sort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both. (Note that a bin may be left empty.)

All of the answers are in both

Which of these gametes contains one or more recombinant chromosomes?

B and C

The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

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.

Look at the cell in the figure. Based on this figure, which of the following statements is true? Look at the cell in the figure. Based on this figure, which of the following statements is true? It is impossible to tell whether the cell is haploid or diploid.This cell is diploid.This cell is haploid.

Diploid

Which of the following processes occur during meiosis but not mitosis?

Diploid cells form haploid cells.

Imagine that there are 25 different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment?

The sexually reproducing species is likely to thrive.

This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?

The two chromatids were formed by duplication of a chromosome.

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.

There would be less genetic variation among gametes. Submit

Which of the following characteristics do homologous chromosomes exhibit?

They carry information for the same characters.

Homologous chromosomes migrate to opposite poles during _____.

anaphase I Submit

During _____ sister chromatids separate.

anaphase II

During which of the following phases of meiosis do centromeres split and sister chromatids migrate to opposite poles of the cell?

anaphase II

Which of these gametes contain one or more recombinant chromosomes?

b, c, f and g

Many organisms spend most of their life cycle in the diploid state. If meiosis produces haploid cells, how is the diploid number restored for these types of organisms?

by fertilization

Which of these cells is (are) haploid?

c and d

Human gametes are produced by _____.

meiosis

The shuffling of chromosomes that occurs during both fertilization and _____ can lead to genetic variation. See Concept 13.4 (Page 265)

meiosis

Synapsis occurs during _____.

prophase I

Meiosis II is similar to mitosis in that

sister chromatids separate during anaphase. Submit

In alternation of generations, what is the diploid stage of a plant that follows fertilization called? See Concept 13.2 (Page 258)

sporophyte

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

telophase I

At the end of _____ and cytokinesis there are four haploid cells.

telophase II