4

4

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

____1.As a cell becomes larger, its

a.

volume increases faster than its surface area.

b.

surface area increases faster than its volume.

c.

volume increases, but its surface area stays the same.

d.

surface area stays the same, but its volume increases.

____2.As a cell grows, it

a.

places more demands on its DNA.

b.

uses up food and oxygen more quickly.

c.

has more trouble moving enough materials across its cell membrane.

d.

all of the above

____3.If the surface area of a cell increases 100 times, its volume increases about

a.

5 times.

b.

10 times.

c.

100 times.

d.

1000 times.

____4.The rate at which wastes are produced by a cell depends on the cells

a.

ratio of surface area to volume.

b.

environment.

c.

volume.

d.

surface area.

____5.All of the following are problems that growth causes for cells EXCEPT

a.

DNA overload.

b.

excess oxygen.

c.

obtaining enough food.

d.

expelling wastes.

____6.Compared to small cells, large cells have more trouble

a.

dividing.

b.

producing daughter cells.

c.

moving needed materials in and waste products out.

d.

making copies of their DNA.

____7.The process by which a cell divides into two daughter cells is called

a.

cell division.

b.

metaphase.

c.

interphase.

d.

mitosis.

____8.Which of the following is NOT a way that cell division solves the problems of cell growth?

a.

Cell division provides each daughter cell with its own copy of DNA.

b.

Cell division increases the mass of the original cell.

c.

Cell division increases the surface area of the original cell.

d.

Cell division reduces the original cells volume.

____9.If a normal cell divides, you can assume that

a.

its surface area has become larger than its volume.

b.

its volume has become larger than its surface area.

c.

it has grown to its full size.

d.

it has grown too large to meet its needs.

____10.If a cells DNA were not copied before cell division, the cell could

a.

have a DNA overload.

b.

become cancerous.

c.

fail to exchange materials.

d.

divide.

____11.Which of the following happens when a cell divides?

a.

The cells volume increases.

b.

It becomes more difficult for the cell to get enough oxygen and nutrients.

c.

The cell has DNA overload.

d.

Each daughter cell receives its own copy of the parent cells DNA.

____12.When during the cell cycle are chromosomes visible?

a.

only during interphase

b.

only when they are being replicated

c.

only during cell division

d.

only during the G1 phase

____13.Which of the following is a phase in the cell cycle?

a.

G1 phase

b.

G2 phase

c.

M phase

d.

all of the above

____14.Which pair is correct?

a.

G1 phase, DNA replication

b.

G2 phase, preparation for mitosis

c.

S phase, cell division

d.

M phase, cell growth

____15.When during the cell cycle is a cells DNA replicated?

a.

G1 phase

b.

G2 phase

c.

S phase

d.

M phase

____16.Which event occurs during interphase?

a.

The cell grows.

b.

Centrioles appear.

c.

Spindle fibers begin to form.

d.

Centromeres divide.

____17.Which of the following is a correct statement about the events of the cell cycle?

a.

Little happens during the G1 and G2 phases.

b.

DNA replicates during cytokinesis.

c.

The M phase is usually the longest phase.

d.

Interphase consists of the G1, S, and G2 phases.

____18.Which of the following is NOT a correct statement about the events of the cell cycle?

a.

Interphase is usually the longest phase.

b.

DNA replicates during the S phase.

c.

Cell division ends with cytokinesis.

d.

The cell grows during the G2 phase.

Figure 101

____19.Cell division is represented in Figure 101 by the letter

a.

A.

b.

B.

c.

C.

d.

D.

____20.The cell cycle is the

a.

series of events that cells go through as they grow and divide.

b.

period of time between the birth and the death of a cell.

c.

time from prophase until cytokinesis.

d.

time it takes for one cell to undergo mitosis.

Figure 102

____21.The structure labeled A in Figure 102 is called the

a.

centromere.

b.

centriole.

c.

sister chromatid.

d.

spindle.

____22.The structures labeled B in Figure 102 are called

a.

centromeres.

b.

centrioles.

c.

sister chromatids.

d.

spindles.

____23.During which phase(s) of mitosis are structures like the one shown in Figure 102 visible?

a.

anaphase and prophase

b.

prophase and metaphase

c.

metaphase only

d.

anaphase and interphase

____24.Which of the following is a phase of mitosis?

a.

cytokinesis

b.

interphase

c.

prophase

d.

S phase

____25.The first phase of mitosis is called

a.

prophase.

b.

anaphase.

c.

metaphase.

d.

interphase.

____26.During which phase of mitosis do the chromosomes line up along the middle of the dividing cell?

a.

prophase

b.

telophase

c.

metaphase

d.

anaphase

____27.Which of the following represents the phases of mitosis in their proper sequence?

a.

prophase, metaphase, anaphase, telophase

b.

interphase, prophase, metaphase, anaphase, telophase

c.

interphase, prophase, metaphase, telophase

d.

prophase, metaphase, anaphase, telophase, cytokinesis

____28.What is the role of the spindle during mitosis?

a.

It helps separate the chromosomes.

b.

It breaks down the nuclear membrane.

c.

It duplicates the DNA.

d.

It divides the cell in half.

____29.The two main stages of cell division are called

a.

mitosis and interphase.

b.

synthesis and cytokinesis.

c.

the M phase and the S phase.

d.

cytokinesis and mitosis.

____30.One difference between cell division in plant cells and in animal cells is that plant cells have

a.

centrioles.

b.

centromeres.

c.

a cell plate.

d.

chromatin.

____31.During normal mitotic cell division, a parent cell having four chromosomes will produce two daughter cells, each containing

a.

two chromosomes.

b.

four chromosomes.

c.

eight chromosomes.

d.

sixteen chromosomes.

____32.What happens when cells come into contact with other cells?

a.

They divide more quickly.

b.

They stop growing.

c.

They produce cyclins.

d.

They produce p53.

____33.Which of the following is a factor that can stop normal cells from growing?

a.

contact with other cells

b.

growth factors

c.

a cut in the skin

d.

cyclin that has been taken from a cell in mitosis

____34.Cells grown in a petri dish tend to divide until they form a thin layer covering the bottom of the dish. If cells are removed from the middle of the dish, the cells bordering the open space will begin dividing until they have filled the empty space. What does this experiment show?

a.

When cells come into contact with other cells, they stop growing.

b.

The controls on cell growth and division can be turned on and off.

c.

Cell division can be regulated by factors outside the cell.

d.

all of the above

____35.Which of the following explains why normal cells grown in a petri dish tend to stop growing once they have covered the bottom of the dish?

a.

The cells lack cyclin.

b.

The petri dish inhibits cell growth.

c.

Contact with other cells stops cell growth.

d.

Most cells grown in petri dishes have a defective p53.

____36.When cytoplasm from a cell that is undergoing mitosis is injected into a cell that is in interphase, the second cell

a.

stays in interphase.

b.

enters mitosis.

c.

stops making cyclin.

d.

loses its p53.

____37.In eukaryotic cells, the timing of the cell cycle is regulated by

a.

the centrioles.

b.

cyclins.

c.

the spindle.

d.

all of the above

____38.Cyclins are a family of closely related proteins that

a.

regulate the cell cycle.

b.

produce p53.

c.

cause cancer.

d.

work to heal wounds.

____39.Which of the following regulate(s) the cell cycle?

a.

growth factors

b.

cyclins

c.

p53

d.

all of the above

____40.Which of the following is an internal regulator of the cell cycle?

a.

cyclins

b.

growth factors

c.

the mitotic spindle

d.

cancer cells

____41.Cancer is a disorder in which some cells have lost the ability to control their

a.

size.

b.

spindle fibers.

c.

growth rate.

d.

surface area.

____42.Cancer cells form masses of cells called

a.

tumors.

b.

cyclins.

c.

growth factors.

d.

p53.

____43.A cell with a defective p53 gene is likely to

a.

divide regularly.

b.

stop dividing.

c.

accumulate chromosomal damage.

d.

combat tumors.

____44.Cancer affects

a.

humans only.

b.

most unicellular organisms.

c.

multicellular organisms.

d.

unicellular organisms.

____45.What is a tumor?

a.

an accumulation of cyclins

b.

a mass of cancer cells

c.

the rapidly dividing cells found at the site of a wound

d.

a defective p53 gene

Modified True/False

Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the sentence or statement true.

____46.As a cells size increases, its ratio of surface area to volume increases. _________________________

____47.As a cells size increases, it places more demands on its DNA. _________________________

____48.The smaller a cell is, the more difficult it is for the cell to move enough materials across its cell membrane. _________________________

____49.Cell division solves the problem of cell growth by increasing cell volume. _________________________

____50.An imaginary cubic cell with a side length of 10 mm would have a ratio of surface area to volume of 6 : 10. _________________________

____51.Most of a cells growth takes place during the phase of the cell cycle. _________________________

____52.A cells chromosomes are replicated during interphase. _________________________

____53.If it takes a cell one hour to undergo mitosis, about 50 minutes of the time would be spent in prophase. _________________________

Figure 102

____54.The structure shown in Figure 102 is a replicated chromosome. _________________________

____55.Typically, the longest phase of mitosis is metaphase. _________________________

____56.A cell splits into two daughter cells during telophase. _________________________

____57.Normal cells stop growing when they come into contact with other cells. _________________________

____58.Proteins called cyclins help regulate the cell cycle. _________________________

____59.Cancer is a disorder in which some of the bodys cells lose the ability to control growth and division. _________________________

____60.Lack of control over mitosis is the cause of all cancers. ______________________________

Completion

Complete each sentence or statement.

61.The larger a cell becomes, the ____________________ efficiently it is able to function.

62.Before a normal cell becomes too large to carry out normal activities, it will usually divide to form two ____________________ cells.

63.The process by which a cell divides into two daughter cells is called _________________________.

64.Together, the G1 phase, S phase, and G2 phase are called ____________________.

65.Another name for cell division is the ____________________ phase.

66.A cell that has 5 chromosomes in the G1 phase will have ____________________ chromatids in the G2 phase.

67.The number of sister chromatids in a human body cell that is entering cell division is ____________________.

Figure 103

68.The structure labeled A in Figure 103 is called the _________________________.

69.The process shown in Figure 103 occurs only in ____________________ cells that have just divided.

70.Look at Figure 103. The process shown occurs directly following mitosis. This process is called ____________________.

71.During metaphase, each chromosome is connected to a(an) _________________________ at its centromere.

72.If a normal cell is touched on all sides by other cells and is injected with cyclin from a dividing cell, it probably will ____________________.

73.Proteins called ____________________ regulate the timing of the cell cycle in eukaryotic cells.

74.Proteins that regulate the cell cycle based on events inside the cell are called ____________________ regulators.

75.In all forms of ____________________, the cancerous cells fail to respond to the signals that regulate the cell cycle of most cells.

Short Answer

76.List two problems that growth causes for cells.

77.How might you test the effects of cell size on the extent of diffusion?

78.What effect does cell size have on a cells ability to efficiently carry out its activities?

79.How does cell division solve the problems of excessive cell growth?

Figure 101

80.The main events of the cell cycle are labeled A, B, C, and D in Figure 101. Name these events. Then, briefly state what happens during each event.

81.Describe how a plant cell produces a new cell wall during cytokinesis.

82.Distinguish between chromatids and chromatin.

83.Many injuries to the skin heal completely, whereas injuries to the spinal cord, which is made up mainly of nerve cells, may result in paralysis. What characteristic of the two types of cells in these body parts accounts for this difference?

84.Identify a factor that can stop cells from growing.

85.What effect do the cells surrounding a normal cell have on the cells growth and division?

86.The level of cyclins in a cell increases during the M phase of the cell cycle. What might happen to a cell if no cyclins were present during the M phase?

87.Name two factors that help regulate the timing of the cell cycle.

88.How do cancer cells differ from normal cells?

89.Cells grown in a petri dish tend to divide until they form a thin layer covering the bottom of the dish. How would you expect cancer cells to behave in this situation?

90.A scientist suspects that a given cell is cancerous even though it has not yet formed a tumor. How might the scientist test the cell to see if it is cancerous?

Other

USING SCIENCE SKILLS

Figure 104

91.Interpreting Graphics What does Figure 104 represent? How do you know if this is an animal cell or a plant cell?

92.Inferring What is the chromosome number of the cell shown in Figure 104?

93.Inferring Identify the structures labeled X and Y in Figure 104.

94.Applying Concepts List the correct order for the diagrams in Figure 104.

95.Predicting After the steps shown in Figure 104 are arranged in the correct order, what would a diagram of the next step show?

USING SCIENCE SKILLS

A student placed three cubes of agar that contained the indicator phenolphthalein in a beaker of vinegar. The cubes were the following lengths: 3 cm, 2 cm, and 1 cm. In the presence of an acid, such as vinegar, phenolphthalein turns from pink to clear. After 10 minutes, the student cut each cube open and measured the distance that the vinegar had diffused into each cube. She then started to complete the data table.

Figure 105

Comparison of Agar Cubes

Cube

Size

(length

in cm)

Surface

Area

(cm2)

Volume

(cm3)

Ratio of

Surface

Area to

Volume

Depth of

Diffusion

(mm)

Time

(minutes)

Rate of

Diffusion

(mm/minute)

3

54

27

10

2

10

1

6

1

10

96.Designing Experiments What is the student probably trying to test? What do the cubes in Figure 105 probably represent?

97.Calculating Look at the data table in Figure 105. What are the surface area, volume, and ratio of surface area to volume for the cube that is 2 cm in length?

98.Comparing and Contrasting Compare the cubes in Figure 105 with respect to their sizes and their ratios of surface area to volume.

99.Inferring Look at the experimental setup in Figure 105. How will the student know how far the vinegar has diffused into each cube?

100.Predicting Predict how the ratio of surface area to volume will relate to the rate of diffusion and the distance that the vinegar will diffuse into each cube in Figure 105.

USING SCIENCE SKILLS

Figure 106

101.Interpreting Graphics Look at Figure 106. Which diagram shows cancer cells? How do you know?

102.Comparing and Contrasting Explain how cancer cells are different from normal cells. Then, relate these characteristics to the diagram in Figure 106 that shows cancer cells.

103.Predicting Look at the cancer cells shown in Figure 106. What can happen if these cells are left untreated?

104.Applying Concepts Explain the role that p53 might have had in the growth and division of the cells shown in each diagram in Figure 106.

105.Problem Solving How might the cancer cells shown in Figure 106 be prevented from doing more harm to the organism they are a part of?

Essay

106.Relate ratio of surface area to volume to cell growth and cell division.

107.What kinds of problems does growth cause for cells? How does cell division help a cell solve these problems?

108.List and describe the main events of the cell cycle. Illustrate your description with a diagram of the cell cycle.

109.Describe what happens during the four stages of mitosis.

110.Discuss the relationship between mitosis and cytokinesis. What would be the result if one happened without the other?

111.Assume that prophase begins with eight chromatids in the nucleus of a cell. When telophase ends, how many chromosomes will be present in each new nucleus? Explain your answer.

112.Describe how the skin cells near a cut behave. What role does contact with other cells have in the behavior of cells near a cut?

113.Describe how the cell cycle is regulated.

114.If you looked at a sample of cells under a microscope, how might you recognize cancer cells?

115.Describe how cancer cells are different from other cells. Based on these differences, explain why cancer has been such a difficult condition to cure.

4

Answer Section

MULTIPLE CHOICE

1.ANS:A

2.ANS:D

3.ANS:D

4.ANS:C

5.ANS:B

6.ANS:C

7.ANS:A

8.ANS:B

9.ANS:C

10.ANS:A

11.ANS:D

12.ANS:C

13.ANS:D

14.ANS:B

15.ANS:C

16.ANS:A

17.ANS:D

18.ANS:D

19.ANS:D

20.ANS:A

21.ANS:A

22.ANS:C

23.ANS:B

24.ANS:C

25.ANS:A

26.ANS:C

27.ANS:A

28.ANS:A

29.ANS:D

30.ANS:C

31.ANS:B

32.ANS:B

33.ANS:A

34.ANS:D

35.ANS:C

36.ANS:B

37.ANS:B

38.ANS:A

39.ANS:D

40.ANS:A

41.ANS:C

42.ANS:A

43.ANS:C

44.ANS:C

45.ANS:B

MODIFIED TRUE/FALSE

46.ANS:F, decreases

47.ANS:T

48.ANS:F, larger

49.ANS:F

reducing

decreasing

lowering

50.ANS:T

51.ANS:F, G1

52.ANS:T

53.ANS:F, 3036 minutes

54.ANS:T

55.ANS:F, prophase

56.ANS:T

57.ANS:T

58.ANS:T

59.ANS:T

60.ANS:F, the cell cycle

COMPLETION

61.ANS:less

62.ANS:daughter

63.ANS:cell division

64.ANS:interphase

65.ANS:M

66.ANS:10

67.ANS:92

68.ANS:cell plate

69.ANS:plant

70.ANS:cytokinesis

71.ANS:spindle fiber

72.ANS:divide

73.ANS:cyclins

74.ANS:internal

75.ANS:cancer

SHORT ANSWER

76.ANS:

As a cell grows larger, more demands are placed on its DNA, and the cell has more trouble moving enough nutrients and wastes across the cell membrane.

77.ANS:

Any method of comparing the extent of diffusion into a small cube and a large cube or into a small sphere and a large sphere will work.

78.ANS:

A large cell carries out its activities less efficiently than a small one does.

79.ANS:

Each of the two daughter cells that result from cell division has its own copy of the parental DNA as well as a reduced volume.

80.ANS:

A: G1 phase, cell growth; B: S phase, DNA replication; C: G2 phase, preparation for mitosis; D: M phase, cell division (mitosis and cytokinesis).

81.ANS:

During cytokinesis, a cell plate forms in the cytoplasm midway between each new nucleus. The cell plate gradually develops into a separating membrane, and a cell wall begins to appear in the cell plate.

82.ANS:

Chromatids are two identical DNA strands joined by a centromere, and chromatin is the material that makes up chromosomes.

83.ANS:

Most nerve cells do not divide once they have developed, whereas many skin cells can divide.

84.ANS:

Contact with other cells can stop cell growth.

85.ANS:

The cells surrounding the cell can stop it from growing and dividing.

86.ANS:

A cell that lacked cyclins would probably not undergo mitotic division, and then it would continue to grow, have DNA overload, and exchange materials inefficiently until it dies.

87.ANS:

Any two of the following: contact with other cells, cyclins, growth factors, and any other internal or external regulators

88.ANS:

Cancer cells do not respond to the signals that control the growth of normal cells. As a result, cancer cells form tumors and can spread throughout the body.

89.ANS:

Cancer cells are not constrained by crowding and would probably continue to grow after forming a thin layer covering the bottom of the petri dish.

90.ANS:

Sample answers: The scientist could culture the cell in a petri dish and see if it responds to the signals that normally regulate the cell cycle. Alternatively, the scientist could test the cells DNA to see if it has a normal copy of the p53 gene.

OTHER

91.ANS:

It shows various stages of mitosis in an animal cell. We know this is an animal cell because of the presence of centrioles and the shape of the cells.

92.ANS:

Four

93.ANS:

X is the centriole; Y is a spindle fiber.

94.ANS:

D, A, C, B

95.ANS:

The next step would be cytokinesis. It would show two daughter cells forming.

96.ANS:

The student is varying the size of the cubes and testing how far a solution can diffuse into each cube; thus, she is probably testing the effect of size on the diffusion of materials into each cube. The cubes probably represent cells.

97.ANS:

Surface area = length width the number of sides = 2 2 6 = 24 cm2. Volume = length width height = 2 2 2 = 8 cm3. Ratio of surface area to volume = 24/8 = 3:1.

98.ANS:

Students should conclude that the largest cube has the smallest ratio of surface area to volume, and the smallest cube has the largest ratio of surface area to volume.

99.ANS:

The vinegar will turn the pink parts of the cube clear. Thus, the student can cut each cube in half and measure the amount of each cube that has changed from pink to clear.

100.ANS:

The rate of diffusion should be constant across all three cubes. The vinegar will diffuse to a greater extent into the smaller cube than into the larger cubes because the ratio of surface area to volume is larger for the smaller cubes.

101.ANS:

Diagram A shows cancer cells because it shows cells that are not growing in an organized way.

102.ANS:

Cancer cells do not respond to the signals that control the growth of most cells. As a result, cancer cells form masses (tumors). These signals include growth factors that stimulate cell division at a proper rate and signals that prevent excessive growth so that tissues do not disrupt each other. Diagram A shows cells that have divided until they have formed a tumor. These cells are dividing more quickly than normal cells do. They have started disrupting adjacent cells.

103.ANS:

They can break loose from the mass they are now a part of and spread throughout the body, disrupting normal activities and causing serious medical problems.

104.ANS:

Diagram A: These cells might have a defect in the p53 gene, which has allowed the cells to multiply more quickly and chaotically than the normal cells. Diagram B: These cells probably have a healthy copy of the p53 gene, which has stopped the cell cycle until the genetic material in these cells has been properly replicated.

105.ANS:

Students may suggest removing the cancerous cells in hopes of preventing their continued division, growth, and spread throughout the body, treating them with radiation or chemicals that will destroy the cells, etc.

ESSAY

106.ANS:

A cells volume increases more rapidly than does it surface area, causing its ratio of surface area to volume to decrease with size (growth). As a cells ratio of surface area to volume decreases, it becomes more difficult for a cell to move needed materials in and wastes out. Thus, a normal growing cell will usually divide into two daughter cells before it becomes too large.

107.ANS:

As a cell grows, it functions less efficiently because it places more demands on its DNA and it is less able to move materials to their proper destinations quickly. Cell division results in two daughter cells. Each cell has its own copy of the parent cells DNA and has a size that allows it to efficiently exchange materials.

108.ANS:

Interphase consists of the G1 phase, S phase, and the G2 phase. During the G1 phase, the cell grows; during the S phase, the DNA replicates; during the G2 phase, the cell prepares for mitosis. The M phase or cell division includes mitosis and cytokinesis. Figures should approximate Figure 10-4 on page 245 of the student text.

109.ANS:

Prophase: the chromatin condenses into chromosomes, the centrioles separate (in animal cells), and the nuclear membrane breaks down; metaphase: the chromosomes line up across the midline of the cell and each chromosome is attached to a spindle fiber and centromere; anaphase: sister chromatids separate into individual chromosomes; telophase: chromosomes move to opposite sides of the dividing cell, and two new nuclear envelopes form.

110.ANS:

Mitosis is the division of the nucleus. Cytokinesis is the division of the cytoplasm. If mitosis occurred without cytokinesis, the cell would contain two nuclei. If cytokinesis occurred without mitosis, one of the new cells would lack DNA and a nucleus altogether.

111.ANS:

When telophase ends, each new nucleus will contain four chromosomes. The eight chromosomes form from the replication of four chromosomes. When mitosis is over, the chromatids have separated at their centromeres to form eight chromosomes, half of which move to each nucleus.

112.ANS:

Cells at the edges of the cut are stimulated to divide rapidly, producing new cells, and healing the wound. When the cut is almost completely healed, the rate of cell division slows down. Thus, when the cells on either side of the cut are no longer in contact with one another, they divide to fill in the gap. Once the cells are in contact with one another, the cut is healed, and the cells resume their normal growth rate.

113.ANS:

The cell cycle is regulated by signals both inside and outside a cell. Internal regulators include proteins that make sure a cell does not divide until after its DNA has been copied faithfully or proteins that prevent a cell from dividing if all its chromosomes are not attached to the spindle. External controls include growth factors that stimulate cell division and molecules on the surfaces of cells that inhibit growth so that cells do not disrupt each others growth.

114.ANS:

Cancer cells lack the cell-cycle regulators that normal cells have. Thus, they are likely to divide at a higher rate than normal cells do and form a mass, or tumor. Also, because cancer cells divide without the controls that ensure proper and complete duplication of their DNA, they are likely to lack some genetic information, which can make them have odd, rather than uniform, shapes, structures, and sizes. Cancer cells may have too many nuclei, for example.

115.ANS:

Unlike normal cells, cancer cells do not respond to normal controls on growth and division. By dividing uncontrollably, cancer cells form tumors and spread throughout the body. A cure for cancer includes a way to both prevent cancer cells from dividing uncontrollably and to allow normal cells to continue dividing normally. Finding a way to stop the cell cycle in some cells, but not interfere with the cell cycle in other cells, has made it difficult to cure cancer.