10 Meiosis and Sexual Life Cycles

Question 1

Asexual reproduction _____.

Answer 1

produces offspring genetically identical to the parent

Only one individual makes a genetic contribution to the offspring

Question 2

What number and types of chromosomes are found in a human somatic cell?

Answer 2

44 autosomes and 2 sex chromosomes

Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males).

Question 3

How are sister chromatids and homologous chromosomes different from each other?

Answer 3

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.

Question 4

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

Answer 4

two … haploid

Question 5

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

Answer 5

four … haploid

Question 6

This animation illustrates the events of _____.

Answer 6

prophase II

The events of prophase II are essentially the same as those of mitotic prophase except that prophase II cells are haploid.

Question 7

This animation illustrates the events of _____.

Answer 7

anaphase II

Question 8

During _____ sister chromatids separate.

Answer 8

anaphase II

Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.

Question 9

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

Answer 9

telophase I

At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.

Question 10

Synapsis occurs during _____.

Answer 10

prophase I

Synapsis, the pairing of homologous chromosomes, occurs during prophase I.

Question 11

Homologous chromosomes migrate to opposite poles during _____.

Answer 11

anaphase I

During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.

Question 12

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

Answer 12

metaphase II

Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.

Question 13

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

Answer 13

telophase II

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

Question 14

During _____ a spindle forms in a haploid cell.

Answer 14

prophase II

Prophase II is essentially the same as mitotic prophase except that the cells are haploid.

Question 15

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?

Answer 15

two diploid cells … four haploid cells

In mitosis a cell that has doubled its genetic material divides to produce two diploid daughter cells. In meiosis a cell that has doubled its genetic material undergoes two rounds of division, producing four haploid cells.

Question 16

Which of the following occurs during meiosis but not during mitosis?
A.Chromosomes condense.
B. Chromosomes align at the metaphase plate.
C. A spindle apparatus forms.
D. Synapsis occurs.
E. Chromosomes migrate to opposite poles.

Answer 16

Synapsis occurs.

The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.

Question 17

What is crossing over?

Answer 17

the exchange of homologous portions of nonsister chromatids

The result is new combinations of genetic material (genetic recombination).

Question 18

Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?.

Answer 18

meiosis

Variation is produced as a result of independent assortment and crossing over.

Question 19

Heritable variation is required for which of the following?

Answer 19

evolution

Variation is the raw material of evolution.

Question 20

A human cell containing 22 autosomes and a Y chromosome is

Answer 20

a sperm.

Question 21

Homologous chromosomes move toward opposite poles of a dividing cell during

Answer 21

meiosis I

Question 22

Meiosis II is similar to mitosis in that

Answer 22

sister chromatids separate during anaphase.

Question 23

What is a locus?

Answer 23

precise location of a gene on a chromosome

Question 24

Sexual and asexual reproduction are alike in that _____.

Answer 24

they can both occur in multicellular organisms

Question 25

A clone is the product of \_\_\_\_\_.

Answer 25

asexual reproduction mitosis

Question 26

A karyotype is \_\_\_\_\_.

Answer 26

a photograph of all of an individual's chromosomes

Question 27

Which, if any, of the following statements is true? Diploid cells can divide by mitosis. Diploid cells can divide by meiosis. Haploid cells can divide by mitosis. Haploid cells cannot divide by meiosis. All of the above responses are correct.

Answer 27

All of the above responses are correct.

Question 28

Which of the following is part of the life cycle called alternation of generations? multicellular haploid stage (gametophyte) multicellular diploid stage (sporophyte) zygote spores all of the above

Answer 28

all of the above

Question 29

A life cycle in which the only multicellular form is haploid is most typical of \_\_\_\_\_.

Answer 29

fungi

Question 30

Sister chromatids are identical copies of each other formed during DNA \_\_\_\_\_\_

Answer 30

synthesis

Question 31

Which of the following statements about homologous chromosomes is correct? They are found in animal cells but not in plant cells. They have genes for the same traits at the same loci. They pair up in prophase II. They are found in haploid cells. They are found in the cells of human females but not in human males.

Answer 31

They have genes for the same traits at the same loci.

Question 32

When we say that an organism is haploid, we mean that \_\_\_\_\_.

Answer 32

its cells have a single set of chromosomes

Question 33

Which of the following is a function of mitosis in humans? production of eggs production of sperm decreasing the number of chromosomes multiplication of body cells increasing genetic variability

Answer 33

multiplication of body cells

Question 34

Somatic cells in humans contain _____ set(s) of chromosomes and are therefore termed \_\_\_\_\_.

Answer 34

two ... diploid

Question 35

Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place \_\_\_\_\_.

Answer 35

at fertilization, when gametes fuse

Question 36

Spores and gametes are different in that \_\_\_\_\_.

Answer 36

gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote

Question 37

Which of the following results in cells that contain half the parental chromosome number?

Answer 37

meiosis

Question 38

The two cell divisions of meiosis, I and II, produce \_\_haploid daughter cells.

Answer 38

four

Question 39

At the end of telophase I of meiosis and the first cytokinesis, there are \_\_\_\_\_.

Answer 39

two haploid cells

Question 40

What is the result when a diploid cell undergoes meiosis?

Answer 40

four haploid cells

Question 41

Synapsis occurs during \_\_\_\_\_.

Answer 41

prophase I

Question 43

Which of the following occurs during anaphase II?

Answer 43

Sister chromatids separate and migrate toward opposite poles.

Question 44

Which of the following occurs during anaphase I?

Answer 44

Homologs separate and migrate toward opposite poles.

Question 45

Cytokinesis is the \_\_\_\_\_.

Answer 45

division of one cell into two

Question 46

Crossing over occurs during \_\_\_\_\_.

Answer 46

prophase I

Question 47

Regions of chromosomes where nonsister chromatids cross over are called \_\_\_\_\_.

Answer 47

chiasmata

Question 48

Which event occurs only during prophase I of the first meiotic division?

Answer 48

Synapsis of homologous pairs occurs.

Question 49

Which of the following occurs in meiosis, but not mitosis?

Answer 49

Homologous chromosomes separate.

Question 50

Which function makes meiosis lengthier and more complex than mitosis? decreasing the chromosome number to haploid introducing genetic variation among the daughter cells ensuring that each daughter cell gets a single, complete set of chromosomes undergoing two rounds of cytokinesis all of the above

Answer 50

all of the above

Question 51

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8?

Answer 51

16

Question 52

The major contribution of sex to evolution is that \_\_\_\_\_.

Answer 52

it provides a method to increase genetic variation

Question 53

Which of the following contributes to genetic variation in sexually reproducing species? crossing over, internal fertilization, independent assortment independent assortment, spindle formation, random fertilization random fertilization, DNA synthesis, independent assortment random fertilization, independent assortment, crossing over internal fertilization, spindle formation, crossing over

Answer 53

random fertilization, independent assortment, crossing over

Question 54

Although _____ is nearly universal among animals, bdelloid rotifers \_\_\_\_\_.

Answer 54

sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers