Test 4 Mitosis and Meiosis

Which of the following happens at the conclusion of meiosis I?

a) Homologous chromosomes are separated.

Synapsis of homologous pairs occurs; crossing over may occur.

a) I

What is a genome?

a) The complete complement of an organism's genes

A human cell containing 22 autosomes and a Y chromosome is

a) a sperm.

The MPF protein complex turns itself off by

a) activating a process that destroys cyclin component.

The centromere is a region in which

a) chromatids remain attached to one another until anaphase.

Meiosis II is similar to mitosis in that

a) sister chromatids separate during anaphase.

Independent assortment of chromosomes is a result of

a) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

b) 20

Density-dependent inhibition is explained by which of the following?

b) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing

If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will..

b) Complete the cycle and divide

The "restriction point" occurs here:

b) G1

Which of the following are primarily responsible for cytokinesis in plant cells?

b) Golgi-derived vesicles

Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment

b) II

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

b) MPF

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

b) Synapsis of chromosomes

A cell divides to produce two daughter cells that are genetically different.

b) The statement is true for meiosis I only.

Homologous chromosomes synapse and crossing over occurs.

b) The statement is true for meiosis I only.

Independent assortment of chromosomes occurs.

b) The statement is true for meiosis I only.

A tetrad includes which of the following sets of DNA strands?

b) Two sets of sister chromatids that have synapsed

What is a chromatid?

b) a replicate chromosome

Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?

b) anaphase

Homologous chromosomes move toward opposite poles of a dividing cell during

b) meiosis I.

The somatic cells derived from a single-celled zygote divide by which process?

b) mitosis

Why do chromosomes coil during mitosis?

b) to allow the chromosomes to move without becoming entangled and breaking

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

b)centrosome

One difference between cancer cells and normal cells is that cancer cells

c )continue to divide even when they are tightly packed together

Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur?

c) Chromosomally abnormal cells can still go through cell cycle checkpoints.

Which of the following is true of a species that has a chromosome number of 2n = 16?

c) Each cell has 8 homologous pairs

You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?

c) Tetrads lined up at the center of the cell

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants

c) cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage

An enzyme that attaches a phosphate group to another molecule is called a

c) kinase.

Which term describes two centrosomes arranged at opposite poles of the cell?

c) prometaphase

Chromosomes first become visible during which phase of mitosis?

c) prophase

Which is a general term for enzymes that activate or inactivate other proteins by phosphorylating them?

c) protein kinase

Cells that are in a nondividing state are in which phase?

a) G0

Nerve and muscle cells are in this phase:

a) G0

at prometaphase of mitosis:

B

DNA is replicated at this time of the cell cycle:

C) S

If there are 20 chromatids in a cell, how many centromeres are there?

a) 10

How does the sexual life cycle increase the genetic variation in a species?

a) By allowing independent assortment of chromosomes

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)?

d) 16

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

d) 32

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes?

d) 46

Chiasmata are what we see under a microscope that let us know which of the following is occurring?

d) Crossing over

Asexual reproduction results in identical offspring unless which of the following occurs?

d) Mutation

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?

d) The daughter cells have the same number of chromosomes and the same amount of DNA.

. Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

d) cyclin

The human X and Y chromosomes

d) include genes that determine an individual's sex.

Which is the longest of the mitotic stages?

d) metaphase

What is a karyotype?

e) A display of every pair of homologous chromosomes within a cell, organized according to size and shape

Which of the following is true concerning cancer cells?

e) A, B, and C (a:They do not exhibit density-dependent inhibition when growing in culture. b) When they stop dividing, they do so at random points in the cell cycle. c) They are not subject to cell cycle controls)

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?

e) About 8 million

Which of the following describe(s) cyclin-dependent kinase (Cdk)?

e) Both B and C are true. (b: Cdk is present throughout the cell cycle. c:Cdk is an enzyme that attaches phosphate groups to other proteins)

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?

e) Cdk

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following?

e) Its gametes must have 23 chromosomes.

The cyclin component of MPF is destroyed toward the end of this phase:

e) M

This is the shortest part of the cell cycle:

e) M

Chromatids are separated from each other.

e) The statement is true for mitosis and meiosis II.

Centromeres of sister chromatids disjoin and chromatids separate.

e) VII

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called

e) cyclins.

During which phases of mitosis are chromosomes composed of two chromatids?

e) from G2 of interphase through metaphase

Which term describes centrioles beginning to move apart in animal cells?

e) prophase