mitosis mastering bio

During _____ both the contents of the nucleus and the cytoplasm are divided. 1.mitosis 2.the mitotic phase 3.G1 4.S 5.G2

2

During which phase of mitosis do the chromatids become chromosomes? 1.telophase 2. anaphase 3.prophase 4.metaphase

2

In dividing cells, most of the cell's growth occurs during

interphase

During mitosis, microtubules attach to chromosomes at the

kinetochore

DNA replication produces two identical DNA molecules, called ____ _____,which separate during mitosis.

sister chromatids

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? 1. 92 2. 46 3. 46 or 92, depending on the portion of prophase examined 4. 23 or 46, depending on the portion of prophase examined 5. 23

1

Besides the ability of some cancer cells to over proliferate, which of the following situations might logically result in a tumor? 1.lack of appropriate cell death 2.inability to form spindles 3.failure of cells to enter S phase 4.changes in the order of cell cycle stages

1

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in 1.G1. 2.prophase. 3.metaphase. 4.G2.

1

Chromosomes become visible during _____. 1.prophase 2.interphase 3.metaphase 4.anaphase 5.prometaphase

1

During _____ the cell grows and replicates both its organelles and its chromosomes. 1.interphase 2.S 3.cytokinesis 4.mitosis 5.G1

1

G1 is associated with which of the following cellular events? 1.normal growth and cell function 2.DNA replication 3.the beginning of mitosis 4.break down of the nuclear membrane

1

In a diploid cell with 5 chromosome pairs (2n = 10), how many centromeres will be found in a nucleus at G2 of the cell division cycle? 1. 10 2. 40 3. 20 4. 5

1

Scientists isolate cells in various phases of the cell cycle. They isolate a group of cells that have 1 1/2 times more DNA than G1 phase cells. What is the most likely part of the cell cycle from which these cells were isolated? 1.in the S phase of the cell cycle 2.in the M phase of the cell cycle 3.between the G1 and S phases in the cell cycle 4.in the G2 phase of the cell cycle

1

Spindle fibers attach to kinetochores during _____. 1.prometaphase 2.metaphase 3.anaphase 4.telophase 5.interphase

1

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization. Thus, Taxol stops mitosis by interfering with which of the following structures or processes? 1.the mitotic spindle 2.chromosome condensation 3.centriole duplication 4.cytokinesis

1

What is the best description of the structure of a chromosome in the nucleus of a non-dividing cell? 1.One long DNA molecule, associated with many proteins. 2.Two long DNA molecules wound around each other, associated with many proteins. 3.One long DNA molecule, with no proteins. 4.Two long DNA molecules wound around each other, with no proteins.

1

Which of the following molecules is released by platelets in the vicinity of an injury? 1.PDGF 2.MPF 3.cyclin 4.Cdk

1

_____ is a carcinogen that promotes colon cancer. 1.fat 2.UV light 3.estrogen 4.a virus 5.testosterone

1

A cleavage furrow is _____. 1.the separation of divided prokaryotes 2.a groove in the plasma membrane between daughter nuclei 3.a ring of vesicles forming a cell plate 4.the space that is created between two chromatids during anaphase

2

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms of DNA would be found in a nucleus at prophase of mitosis? 1. 24 2. 16 3. 4 4. 8

2

At which phase of the cell cycle do centrioles begin to move apart in animal cells? 1.telophase 2.prophase 3.metaphase 4.anaphase

2

How is plant cell cytokinesis different from animal cell cytokinesis? 1.The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells. 2.Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow. 3.The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile proteins. 4.Plant cells divide after metaphase but before anaphase; animal cells divide after anaphase.

2

If there are 40 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis? 1. 40 2. 20 3. 10 4. 80

2

In a diploid cell with 5 chromosome pairs (2n = 10), how many sister chromatids will be found in a nucleus at prophase of mitosis? 1. 40 2. 20 3. 10 4. 5

2

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? 1.inability to duplicate DNA 2.large cells containing many nuclei 3.a decrease in chromosome number 4.a rapid rate of gamete production 5.division of the organism into many cells, most lacking nuclei

2

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA? 1. G1 2. G2 3. S 4. G0

2

Nucleotides can be radiolabeled before they are incorporated into newly synthesized DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into a culture of dividing human cells at specific times. Which of the following question might be answered by using the method described? 1.How many cells are produced by the culture per hour? 2.What is the length of the S phase of the cell cycle? 3.When do spindle fibers attach to chromosomes? 4.How many picograms of DNA are made per cell cycle?

2

One difference between cancer cells and normal cells is that cancer cells 1.cannot function properly because they are affected by density-dependent inhibition. 2.continue to divide even when they are tightly packed together. 3.are unable to synthesize DNA. 4.are arrested at the S phase of the cell cycle. 5.are always in the M phase of the cell cycle.

2

The mitotic spindle plays a critical role in which of the following processes? 1.triggering the compaction and condensation of chromosomes 2.separation of sister chromatids 3.splitting of the cell (cytokinesis) following mitosis dissolving the nuclear membrane

2

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________. 1.an animal cell in the process of cytokinesis 2.a plant cell in the process of cytokinesis 3.a plant cell in metaphase of mitosis 4.an animal cell in anaphase of mitosis

2

What is true of all cancers? 1.They are inherited. 2.They have escaped normal cell cycle controls. 3.They are caused by chemical carcinogens.

2

Density-dependent inhibition is explained by which of the following processes? 1.As cells become more numerous, the level of waste products increases, which slows metabolism and inhibits growth. 2.As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. 3.As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing. 4.As cells become more numerous, they begin to squeeze against each other, restricting their size.

3

During prophase a homologous pair of chromosomes consists of _____. 1.one chromosome and four chromatids 2.four chromosomes and two chromatids 3.two chromosomes and four chromatids 4.one chromosome and two chromatids 5.two chromosomes and two chromatids

3

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct? 1.The chromosomes are preparing for DNA synthesis. 2.Each chromosome consists of two identical chromatids. 3.Each chromosome is made of a complex of DNA and associated proteins

3

Movement of the chromosomes during anaphase would be most affected by a drug that prevents which of the following events in mitosis and cell division? 1.formation of a cleavage furrow 2.elongation of microtubules 3.shortening of microtubules 4.nuclear envelope breakdown

3

What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle? 1.kinetochore 2.centriole 3.centrosome 4.centromere

3

What two components constitute an active MPF? 1.ATP synthetase and a protease 2.a growth factor and mitotic factor 3.cyclin and a cyclin-dependent kinase 4.cyclin and tubulin

3

Which of the following correctly matches a phase of the cell cycle with its description? See Concept 12.2 ( page 237) Hints 1.S: immediately precedes cell division 2.M: duplication of DNA 3.G1: follows cell division 4.G2: cell division 5.All of the above are correctly matched.

3

Which of the following events occurs during interphase of the cell cycle? 1.condensation of the chromosomes 2.spindle formation 3.replication of the DNA 4.separation of the spindle poles

3

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. 1.interphase 2.metaphase 3.telophase 4.anaphase 5.prometaphase

4

Cytokinesis often, but not always, accompanies _____. 1.interphase 2.prometaphase 3.metaphase 4.telophase 5.anaphase

4

Eukaryotic chromosomes are composed of which of the following macromolecules? 1.DNA only 2.DNA and RNA 3.DNA and phospholipids 4.DNA and proteins

4

In what way do kinetochore microtubules facilitate the process of splitting the centromeres? 1.They use motor proteins to hydrolyze the centromere at specific arginine residues. 2.They phosphorylate the centromere, thereby changing its conformation. 3.They slide past each other like actin microfilaments. 4.They create tension by pulling toward opposite poles.

4

Metaphase is characterized by ________. 1.separation of the centromeres 2.cytokinesis 3.separation of sister chromatids 4.alignment of chromosomes on the equator of the cell

4

Starting with a fertilized egg (zygote), a series of six cell divisions would produce an early embryo with how many cells? 1. 16 2. 32 3. 12 4. 64

4

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely 1.an animal cell in the process of cytokinesis. 2.a bacterial cell dividing. 3.a plant cell in metaphase. 4.a plant cell in the process of cytokinesis. 5.an animal cell in the S phase of the cell cycle.

4

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to 1.inhibition of DNA synthesis. 2.myosin denaturation and inhibition of cleavage furrow formation. 3.inhibition of regulatory protein phosphorylation. 4.disruption of mitotic spindle formation. 5.suppression of cyclin production.

4

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? See Concept 12.3 ( page 244) 1.G2 2.M 3.cytokinesis 4.S 5.G1

5

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? See Concept 12.3 ( page 244) Hints Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? See Concept 12.3 ( page 244) G2 M cytokinesis S G1

5

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? See Concept 12.2 ( page 237) Hints 1.binary fission 2.DNA replication 3.formation of the cell plate 4.formation of the mitotic spindle 5.cleavage

5

Nucleoli are present during _____. 1.metaphase 2.prophase 3.anaphase 4.prometaphase 5.interphase

5

Which of the following does not occur during mitosis? 1.separation of sister chromatids 2.separation of the spindle poles 3.spindle formation 4.condensation of the chromosomes 5.replication of the DNA

5

Which of these is NOT a carcinogen? 1.UV light 2.cigarette smoke 3.testosterone 4.fat 5.all of the above are carcinogens

5

Why is it difficult to observe individual chromosomes with a light microscope during interphase? See Concept 12.1 ( page 235) 1.They leave the nucleus and are dispersed to other parts of the cell. 2.The spindle must move them to the metaphase plate before they become visible. 3.Sister chromatids do not pair up until division starts. 4.The DNA has not been replicated yet. 5.They have uncoiled to form long, thin strands.

5

After chromosomes condense, the ____ is the region where the identical DNA molecules are most tightly attached to each other.

centromere

are the organizing centers for microtubules involved in separating chromosomes during mitosis.

centrosomes

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called

chromatin

In most eukaryotes, division of the nucleus is followed by _____, when the rest of the cell divides.

cytokenesis

is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

mitotic spindles

are sister chromatids present in all or part of the g1 phase?

no

are the sister chromatids present in the end of M (late anaphase ---> telophase)?

no

does the cell contain twice as much DNA in the G1 phase as it did in the G1 phase?

no

is the DNA condensed in all or part of the G1 phase?

no

is the DNA condensed in all or part of the G2 phase?

no

is the DNA condensed in all or part of the S phase?

no

are the sister chromatids present in all or part of the S phase?

yes

are the sister chromatids present in all or part of the beginning of M (prophase ---> early anaphase)?

yes

are the sister chromatids present in all or part of the g2 phase?

yes

does the cell contain twice as much DNA in the G2 phase as it did in the G1 phase?

yes

does the cell contain twice as much DNA in the S phase as it did in the G1 phase?

yes

does the cell contain twice as much DNA in the beginning of M phase (prophase ---> early anaphase) as it did in the G1 phase?

yes

does the cell contain twice as much DNA in the end of M (anaphase ---> telophase) as it did in the G1 phase?

yes

is the DNA condensed in all or part of the beginning of M (prophase ---> early anaphase)?

yes

is the DNA condensed in all or part of the end of M (late anaphase---> telophase)

yes