STUDY GUIDE FOR CELLS TEST

True/False

____ 1. An element is a pure substance that cannot be broken down into other substances by physical or chemical

means.

____ 2. If a neutral atom contains 18 protons, it also contains 18 electrons.

____ 3. Van der Waals forces are attractive forces between molecules.

____ 4. When an endothermic chemical reaction takes place, heat is released into the environment.

____ 5. A substrate binds to an enzyme’s active site.

____ 6. In a molecule of water, the electrons are more strongly attracted to the hydrogen nuclei than to the oxygen

nucleus. Therefore electrons spend more time near the hydrogen nuclei and there is an unequal sharing of

electrons.

____ 7. During the light-independent reactions of photosynthesis, light energy is used to split water molecules

generating protons and oxygen molecules.

____ 8. In the first step of the Calvin cycle called carbon fixation, three carbon dioxide molecules combine with six

5-carbon compounds to form twelve 3-carbon molecules called 3-phosphoglycerate.

____ 9. Glycolysis generates two ATP and two pyruvate. Only a small amount of the energy from the glucose is

contained in the pyruvate.

____ 10. Alcohol fermentation is similar to lactic-acid fermentation in that NADH donates electrons during this

reaction and NAD+ is regenerated.

Multiple Choice

____ 11. ____ represents a formula for a chemical compound.

a. H c. P

b. C d. H2O

____ 12. An atom of fluorine has nine electrons. Its second energy level has ____.

a. two electrons c. seven electrons

b. eight electrons d. nine electrons

____ 13. Which of the atoms pictured in Figure 6-1 is most likely to form an ion?

Figure 6-1

a. C

b. Na

c. O

d. they are all equally likely to form an ion

____ 17. In the periodic table of the elements, elements in Group 1 have how many outer electrons?

a. 0 c. 4

b. 1 d. 8

____ 18. One isotope of carbon differs from another in which way?

a. atomic number c. number of neutrons

b. number of electrons d. number of protons

____ 19. Two substances are combined and heat is produced. Does this provide evidence that a chemical reaction took

place?

a. No, because heat is not a chemical.

b. No, because this would be a physical change.

c. Yes, because energy is absorbed.

d. Yes, because energy is released.

Figure 6-3

____ 20. Consider the energy diagram for a chemical reaction in Figure 6-3. Overall, is energy released or absorbed?

a. absorbed, because the energy level increases during the reaction

b. absorbed, because the energy level of the products is greater than that of the reactants

c. released, because the reaction is initiated by the addition of heat

d. released because the energy level of the reactants is greater than that of the products

____ 21. A spontaneous chemical reaction occurs more rapidly when the reactants are held at 35ºC rather than 25

ºC.

Why would this be the case?

a. The activation energy would be lower.

b. The activation energy would be higher.

c. The net energy release would be lower.

d. The net energy release would be greater.

____ 22. How does an enzyme influence a biological reaction?

a. It increases the net energy difference between reactants and products.

b. It decreases the activation energy necessary to initiate the chemical change.

c. It increases the kinetic energy of reactants, thereby increasing their tendency to collide.

d. It decreases the kinetic energy of reactants, enabling them to undergo chemical change

more easily.

____ 23. Capillary action is the result of adhesion. Which aspect of water is responsible for this?

a. hydrogen bonds between water and another substance

b. polar covalent bonds that join molecules of water to other substances

c. nonpolar covalent bonds that enable water to dissolve other substances

d. ionic bonds that enable electrons to flow through water and into another substance

____ 25. Which beverage is the best example of a colloid?

a. black coffee c. milk

b. root beer d. tea

____ 26. When added to water, how does an acid affect the pH and H+ concentration?

a. Both pH and H+ decrease.

b. Both pH and H+ increase.

c. The pH decreases while the H+ increases.

d. The pH increases while the H+ decreases.

____ 27. Which element is found in proteins but not carbohydrates or lipids?

a. C c. N

b. H d. O

____ 28. In humans and other multicelluar organisms, which substance plays a central role as an energy source?

a. carbohydrate c. protein

b. fat d. water

Figure 7-3

____ 29. What is the approximate size of A in Figure 7-3?

a. 400 m c. 700 m

b. 500 m d. 1000 m

____ 30. Which of the following pictures in Figure 7-5 most likely approximate the motion phospholipids make in a

plasma membrane?

Figure 7-5

a. A c. C

b. B d. D

____ 31. Both Schwann and Virchow developed important theories about cells in the mid 1800s. Which best explains

the reason these theories were made within a few years of each other?

a. Hooke’s Micrographia inspired both theories.

b. New microscopes provided better viewing of cells.

c. Scientists invented the microscope in the mid 1800s.

d. The electron microscope was used for the first time.

____ 33. Which statement is true about bacterial cells?

a. The cells are very large. c. They are eukaryotes.

b. The cells have no nucleus. d. They have organelles.

____ 34. Cholesterol is repelled by water and can be found between the layers of the phospholipids in the plasma

membrane. What can be concluded from this information?

a. A high cholesterol diet should be avoided.

b. Cholesterol is nonpolar.

c. Cholesterol is polar.

d. Cholesterol is repelled by the polar tails.

____ 35. At what point in the process of diffusion is dynamic equilibrium reached?

a. when the movement of the molecules stops being random

b. when the molecules are mixed and stop moving

c. when the rate of change in the solution slows by one half

d. when there is continuous movement but no change

____ 36. What is a major difference between facilitated diffusion and active transport?

a. Active transport moves substances against the concentration gradient.

b. Active transport uses proteins in the process.

c. Facilitated diffusion moves molecules through the plasma membrane.

d. Facilitated diffusion requires large amounts of energy.

____ 37. Algal cells are placed in an isotonic solution. Additional amounts of solutes are slowly added to the solution.

What happens to the cells?

a. They will begin to swell. c. They will stay the same.

b. They will burst. d. They will shrink.

____ 38. Which of the following is an example of passive transport?

a. endocytosis c. facilitated diffusion

b. exocytosis d. Na+/K

+ ATPase pump

____ 39. Which of the diagrams in Figure 8-1 show how energy is produced in a cell?

Figure 8-1

a. A c. C

b. B d. D

____ 40. What is the main purpose of the cycle shown in Figure 8-3?

Figure 8-3

a. sugar production c. production of ADP

b. destruction of CO2 d. production of NADP-

____ 41. In which types of organisms does the process shown in Figure 8-4 take place?

Figure 8-4

a. plants only c. neither plants nor animals

b. animals only d. both plants and animals

____ 42. During photosynthesis light energy is converted to the energy in chemical bonds. What also happens

according to the predictions of the second law of thermodynamics?

a. chemical energy is converted to light energy

b. matter is lost in the process

c. heat is released in the process

d. the light and chemical energy are equal

____ 43. What results from the removal of a phosphate group from ATP?

a. the production of mechanical energy

b. the release of energy

c. the creation of energy

d. the absorption of energy by chlorophyll

____ 44. Infer why chloroplasts are found mostly in the leaves of plants.

a. The large surface area of leaves allows for maximum light absorption.

b. The waxy coating on the surface of leaves helps prevent evaporation.

c. Chlorophyll interferes with the xylem and phloem in the stems and trunks of plants.

d. The large surface area of leaves allows for contact with oxygen.

____ 45. Which of the following is an accurate description of how structure enhances function in the thylakoid?

a. Thylakoid membranes have a large surface area that provides the space needed to hold

large numbers of electron-transporting molecules.

b. Thylakoid membranes serve as an impermeable surface that prevents the flow of electrons

into the stroma.

c. Thylakoid membranes can open and close depending on humidity to prevent evaporation

from the cell.

d. Thylakoid membranes act as an oxygen barrier allowing the aerobic steps of

photosynthesis to proceed.

____ 46. Which of the following is an accurate summary of chemiosmosis?

a. Oxygen atoms diffuse down their concentration gradient out of the stroma into the grana

through ion channels in the membrane.

b. Hydrogen atoms diffuse down their concentration gradient out of the chloroplasts into the

thylakoid membrane.

c. Hydrogen atoms move up their concentration gradient through active transport out of the

thylakoid into the stroma through ion channels in the membrane.

d. Hydrogen atoms diffuse down their concentration gradient out of the thylakoid into the

stroma through ion channels in the membrane.

____ 47. Which of the following are produced by reactions that take place in the thylakoids and are consumed by

reactions in the stroma?

a. carbon dioxide and water c. ATP and NADPH

b. carbon dioxide and ATP d. ATP and oxygen

____ 48. The energy acquired in photosynthesis is used to make glucose. Where is the glucose made in plants?

a. in the thylakoid c. in the stroma

b. in the thylakoid membrane d. outside the chloroplast

____ 49. The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night.

Which of the following statements explains why not?

a. The Calvin cycle depends on products of light reactions.

b. Carbon dioxide is not available at night.

c. It is too cold at night for reactions to take place.

d. Most plants do not make the 4-carbon compounds that would be needed for the Calvin

cycle to occur at night.

____ 50. Where does the oxygen used in cellular respiration end up?

a. water c. NADH

b. ATP d. glucose

Completion

51. When atoms share electrons equally, they form a(n) ____________________ bond.

52. When a mixture or substance changes color or heats up, this provides evidence that a

____________________ has taken place.

53. Molecules that have an unequal distribution of charges are called ____________________ molecules.

54. The electrostatic attraction between adjacent water molecules is called a(n) ____________________ bond.

55. The movement of protons during ATP production is called ____________________.

56. Hydrogen ion concentration is ____________________ outside the thylakoid membrane than inside.

57. Light-absorbing colored molecules called ____________________ are found in the thylakoid membranes of

photosynthetic organisms.

58. The membrane-bound final receptor of electrons from photosystem I is ____________________.

59. ____________________ is the final stage of aerobic respiration.

60. A group of accessory pigments responsible for the yellow and orange color in carrots and sweet potatoes are

____________________.

Short Answer

Figure 6-4

61. How many electrons are in the third energy level of a magnesium atom? Refer to Figure 6-4.

62. Which compound shown in Figure 6-4 is formed by covalent bonding? Explain.

63. In plants, cells that transport water against the force of gravity are found to contain many more mitochondria

than do some other plant cells. What is the reason for this?

64. Folded membranes have important uses in the cell. Describe at least four of these uses.

65. The cell theory includes three basic principles. Which of these principles was the last to be reported? Explain

the reason that this principle was the last to be understood.

66. For what reason do scientists believe that prokaryotic cells are similar to the first organisms on Earth?

67. Describe how organelles move within the eukaryotic cell.

68. Compare and contrast the terms aerobic process and anaerobic process.

69. How is ATP obtained from aerobic processes?

70. In an experiment to determine whether green plants take in CO2, a biologist filled a large beaker with

aquarium water to which she added bromothymol blue. She exhaled CO2 into the solution of bromothymol

blue to turn it yellow. Then she placed a sprig of Elodea into two test tubes. She left the third test tube without

Elodea to serve as a control. She added the yellow bromothymol solution to all three test tubes and placed a

stopper in each. Next, she placed all the test tubes in sunlight. After several hours in sunlight, the

bromothymol solution in the test tubes with the Elodea turned blue. The bromothymol solution in the control

remained yellow. What conclusion can be drawn from the observations? Explain.

Problem

71. Explain how the invention of the microscope supports this statement: The ability to understand a fact of

nature is limited by our ability to observe it.

72. Doctors recently observed that some long-distance runners were drinking too much water before and during a

race. The excess water was causing serious short-term medical problems for the runners. Use principles of

water diffusion to explain how drinking too much water might be harmful to a runner.

73. Your body makes NAD

+ and FAD from two B vitamins, niacin and riboflavin. The recommended dietary

allowance for niacin is only about 200 mg daily and for riboflavin, 2.0 mg. These amounts are thousands of

times less than the amount of glucose your body needs each day for fuel. How many FAD and NAD+

molecules are needed for the breakdown of each glucose molecule? Why do you think the amount is so small?

Essay

74. Explain how a buffer influences the pH of a solution, and why buffers are important in blood.

75. Explain the essential conflict that land plants have between holding in water and acquiring carbon dioxide and

how some plants have solved this conflict.

STUDY GUIDE FOR CELLS TEST

Answer Section

TRUE/FALSE

1. ANS: T

This is the definition.

2. ANS: T

The number of protons equals the number of electrons.

3. ANS: T

This is correct, and it explains why water molecules stick together.

4. ANS: F

This is true for an exothermic reaction, not endothermic.

5. ANS: T

This is the correct description.

6. ANS: F

Electrons spend more time near the oxygen nucleus.

7. ANS: F

This occurs during the light-dependent reactions.

8. ANS: F

Six carbon dioxide molecules combine with the six 5-carbon molecules.

9. ANS: F

Most of the energy from the glucose is contained in the pyruvate.

10. ANS: T

This happens in both cycles.

MULTIPLE CHOICE

11. ANS: D

A compound contains a fixed ratio of more than one element.

Feedback

A This is an element. B A compound contains more than one element. C This is an element. D Correct. Water contains two elements in a fixed ratio.

12. ANS: C

There are two electrons in the first level, leaving 7 in the second.

Feedback

A This is the number in the first level. B There are two in the first level, so there cannot be eight in the second. C This is correct. D This is the total number.

13. ANS: B

The atom with one electron in its outer energy level is likely to lose it and form an ion.

Feedback

A Carbon atoms usually form covalent bonds. B This is correct. C Oxygen atoms usually form covalent bonds. D If the number of outer electrons varies, chances are the ability to form ions will vary

too.

17. ANS: B

Group 1 elements, when neutral, have 1 outer electron.

Feedback

A None of the elements, when neutral, have zero electrons. B Well done. C Elements in Group 14 have four outer electrons, when neutral. D Elements in Group 18 have 8 outer electrons when neutral.

18. ANS: C

Isotopes differ in the number of neurons.

Feedback

A This is the same as the number of protons, which is always six for carbon. B If neutral, carbon will always have six electrons. C Very good. D Carbon always has six protons.

19. ANS: D

One sign of some chemical reactions is that heat is produced.

Feedback

A Heat is often produced during a chemical reaction. B This would not be a physical change. C Energy is not absorbed. D Well done.

20. ANS: D

The reactants have more energy than the products, which means energy is lost to the environment.

Feedback

A Energy does not increase. B Energy level of products is lower than that of reactants. C Addition of heat to initiate a reaction is beside the point. D Correct.

21. ANS: A

The activation energy is key. Reactants must reach a certain energy level for the reaction to proceed. The

activation energy is the energy needed to reach this level.

Feedback

A Correct. With more energy in the reactants, less must be added to initiate the reaction. B The opposite is true. C The opposite is true. D This is true, but it does not explain the primary reason for the increased rate of the

reaction.

22. ANS: B

By lowering the activation energy, an enzyme increases the rate of the reaction.

Feedback

A This does not change with a catalyst. B Correct. C Temperature influences kinetic energy of reactants. D See page 159.

23. ANS: A

Adhesion is caused by hydrogen bonds between water and some surface.

Feedback

A Well done. B Covalent bonds hold water molecules together but do not connect to other molecules. C Water has polar bonds. D Water has covalent bonds.

25. ANS: C

A colloid has particles that are suspended but not dissolved. The protein and fat of milk is suspended in the

water.

Feedback

A This is a solution. B Even the carbon dioxide dissolves. C Correct. D This is a solution.

26. ANS: C

The pH decreases as the H+ increases.

Feedback

A Only pH decreases. B The pH would decrease. C Correct. D This is opposite of the correct answer.

27. ANS: C

Proteins have nitrogen, but carbohydrates and lipids do not.

Feedback

A All have C. B All have H. C Correct. D All have O.

28. ANS: A

Carbohydrate is the key substance for energy metabolism. Fat is used for storage but not typically as a direct

energy source.

Feedback

A Well done. B This is mostly for energy storage, not use. C This can be used for energy but that is not its main role. D Water does not provide energy, though it is essential for life.

29. ANS: A

The size for the diameter of the viewing area is shown as 1000 m. Figure A is less than half this length. A

length of 400 m is the right answer.

Feedback

A You're right! B That's a little too large. C Try again. D Compare Figure A with the diameter of the circle.

30. ANS: C

Phospholipids have nonpolar tails that always face toward the middle of the membrane. The polar heads

always face away from the middle. The phospholipids can move sideways but cannot move apart or away

from the membrane. Only C shows this movement.

Feedback

A The layers must stay together. B Think about it some more. C That's correct! D The polar heads can't move that way.

31. ANS: B

Better microscopes allowed scientists to see the workings of cells more clearly. This led to the formulation of

the cell theory.

Feedback

A No, try again. B Right! C The microscope was invented in the 1600s. D Check the timeline on page 183.

33. ANS: B

All bacteria are prokaryotes. Although they do contain genetic material, it is not located in a nucleus.

Feedback

A No, try again. B You're right. C No, bacteria are prokaryotes. D Look at page 186 for more information.

34. ANS: B

The phospholipids that make up the plasma membrane are in two layers. The area between the layers is where

the nonpolar tails come together. Because polar substances are repelled by the nonpolar tails, cholesterol must

be nonpolar.

Feedback

A No, try again. B You're right. C Read about polar and nonpolar molecules on page 189. D Think about it some more.

35. ANS: D

The molecules in a solution always are in movement and this movement is random. Dynamic equilibrium is

reached when the concentration is equal in all parts of the solution.

Feedback

A No, movement is always random. B No, molecules always continue to move. C Try again. D That's right.

36. ANS: A

Both active transport and facilitated diffusion use proteins in the process of moving substances through the

plasma membrane. However, active transport moves substances against the concentration gradient while

facilitated diffusion moves materials with the gradient.

Feedback

A Yes, that's right. B No, both process use proteins. C Look on page 204. D No, facilitated diffusion doesn't need extra energy.

37. ANS: D

As the solution becomes more concentrated, it will become increasingly hypertonic. It will then draw water

from the algal cells and cause them to shrink.

Feedback

A No, try again. B Read the information on page 205. C Think about it some more. D You're right.

38. ANS: C

Endocytosis, exocytosis, and the Na+/K

+ ATPase pump all are examples of active transport. Facilitated

diffusion is an example of passive transport.

Feedback

A No, this process takes lots of energy. B Try again. C You're correct! D Look at pages 205–207.

39. ANS: B

A phosphate is added to ADP to produce ATP, requiring energy, while a phosphate is removed from ATP to

produce ADP, releasing energy.

40. ANS: A

The Calvin cycle takes the energy produced in the light reactions and stores it in the bonds in glucose.

41. ANS: D

Glycolysis occurs in both plants and animals and in many other organisms.

42. ANS: C

The second law predicts a loss of energy in the form of heat, an increase in entropy of the system.

Feedback

A Refer to pages 218–219 for more information. B Carefully read both laws of thermodynamics and try again. C Correct! D Did you consider all the factors?

43. ANS: B

When ATP is broken down, energy is released.

Feedback

A Refer to page 221 for more information. B That's correct! C Can energy be created? D Think again! You are getting close.

44. ANS: A

Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis.

Chloroplasts capture light energy from the Sun to produce the energy for plants. Leaves have large surfaces,

which act as light collectors for plants.

Feedback

A Good job! B Try again. C Hmmm....think again. D Good thinking, but not the right answer.

45. ANS: A

Thylakoids are a membrane-bound compartment inside the chloroplasts. The membrane is folded repeatedly

into a stack of disks called grana, that look like a stack of pancakes. The membrane provides a large surface

area for photosystems I and II and serves as a membrane through which electrons flow during chemiosmosis.

Feedback

A Correct. Good work! B Refer to page 224 for more information. C You're on the right track. D This can be confusing. Think carefully.

46. ANS: D

During chemiosmosis a gradient of hydrogen atoms builds up across the thylakoid membrane. The hydrogen

atoms then diffuse down their concentration gradient from the thylakoid into the stroma, generating ATP.

Feedback

A Refer to page 224 for more information. B Keep trying—this is a tough one. C Almost. Would molecules diffuse "up"? D Good job!

47. ANS: C

ATP and NADPH are produced during the light reactions in the thylacoids. They are then consumed during

the light-independent reactions that take place in the stroma.

Feedback

A Refer to page 223 for more information. B Almost! Check your text again. C Good job! This was a tough one! D Did you consider all the factors?

48. ANS: D

The glucose is made outside the chloroplast from the glyceraldehyde 3-phosphate (G3P) produced by the

Calvin cycle.

Feedback

A Refer to page 226 for more information. B This contains the electron transport and photosystems. C This is where the Calvin cycle takes place. D Correct!

49. ANS: A

The light-independent Calvin cycle uses the energy from molecules created during the light reactions.

Feedback

A Correct! B Are you sure about that? C Reactions can take place at very low temperatures. D Refer to page 226 for more information.

50. ANS: A

In cellular respiration, protons and electrons join with oxygen to produce water.

Feedback

A Correct! B Check your text again. C You're on the right track. D Refer to pages 228–231 for more information.

COMPLETION

51. ANS: covalent

52. ANS: chemical reaction

53. ANS: polar

54. ANS: hydrogen

55. ANS: chemiosmosis

56. ANS: higher

57. ANS: pigments

58. ANS: ferrodoxin

59. ANS: Electron transport chain

60. ANS: carotenoids

SHORT ANSWER

61. ANS:

Two

62. ANS:

Hydrogen fluoride; it is formed by covalent bonding because two electrons, one from each atom, are shared

by each hydrogen fluoride molecule.

63. ANS:

Mitochondria are organelles that produce energy for cell reactions; active cells usually have more

mitochondria than do less active cells. It would be reasonable to conclude that the number of mitochondria is

in direct relation to the amount of work done by the cells.

64. ANS:

Membranes are useful for providing a surface for cell reactions. Efficiency of the cell processes is increased

by folded membranes. Folded membranes can be used to make compartments. They also can be used to make

canals for transport of substances.

65. ANS:

The last principle to be reported was that cells arise only from previously existing cells. Scientists developed

the principles of the cell theory based on careful observation of cells using microscopes. The last principle

required more careful observation, and it also was based on the understanding of the first two principles.

66. ANS:

Prokaryotic cells do not have specialized internal structures and are therefore less complex than eukaryotic

cells. Prokaryotes are single-celled organisms. Because the first organisms on Earth were unicellular,

scientists believe that the first cells were prokaryotic.

67. ANS:

Organelles are found within the semi-fluid cytoplasm.The organelles are supported by a supporting network

of thin protein fibers called the cytoskeleton. The cytoskeleton supports the organelles, but it can rapidly

assemble and disassemble allowing the organelles to move within the cell.

68. ANS:

Aerobic processes require oxygen; anaerobic processes do not.

69. ANS:

Answers may include: Aerobic respiration in the mitochondria begins with the production of pyruvic acid

from glycolysis. The citric acid cycle and electron transport chain produce additional ATP molecules as the

carbohydrate is broken down into water and carbon dioxide.

70. ANS:

Because the bromothymol in the control was still yellow, the CO2 did not leak out of the test tubes. Therefore,

in the other two test tubes, the Elodea must have taken in the CO2.

PROBLEM

71. ANS:

The statement is supported because the understanding of the cell came about because of microscopes that

allowed scientists to observe cells. Scientists could not know that cells existed until they could see them with

a microscope. As microscopes got better, scientists were able to develop deeper understandings about the

workings of cells.

72. ANS:

Drinking great quantities of water causes the substances in the bloodstream to be diluted. This means that the

runner’s cells would be in a hypotonic solution and water would flow into the cells. As more and more water

flows into the cells, the cells expand so that they no longer function normally, and some cells might be in

danger of bursting.

73. ANS:

10 NAD+ and 2 FAD are needed to ferry electrons and hydrogen atoms from a single glucose molecule.

NAD+ and FAD are recycled between the electron transport chain and glycolysis and the Krebs cycle. The

human body only needs a small additional supply to replace those molecules that are damaged.

ESSAY

74. ANS:

A buffer stabilizes changes in the pH of a solution. For example, as an acid is added, the buffer binds the

excess H+ ions to reduce the severity of the drop in pH. Similarly, as a base is added, the buffer binds the

excess OH– ions to reduce the severity of an increase in pH.

Buffers are important in blood because various enzymes work best at very specific pH values. The stable pH

ensures that biological reactions proceed as necessary to ensure health.

75. ANS:

Plants acquire carbon dioxide for photosynthesis through stomata in their leaves. They need the carbon

dioxide during the day when photosynthesis is consuming it and so they generally have to have their stomata

open during the day. The day is also when it is warmest and this leads to evaporation of water. Thus plants

can make food only with their stomata open, but to do so they risk drying out. Some plant groups have

adapted to dry climates by modifying their photosynthesis so that the stomata can be open at night taking in

carbon dioxide (and losing less water) that is stored and then used during the day. The stomata are closed

during the day to prevent water loss. These are the CAM and C4 plants.