Study Island

Cell Energy Keystone Review

1. Cells obtain energy by either capturing light energy through photosynthesis or by breaking

down carbohydrates through cellular respiration. In both photosynthesis and cellular respiration,

the energy is ultimately derived from the Sun in a

A. reversible process.

B. one-way process.

C. pathway that involves taking in heat from the environment at each step.

D. highly efficient process which involves no loss of heat to the environment.

2.

Which organelle in the plant cell shown above makes glucose from sunlight?

A. vacuole

B. chloroplast

C. nucleus

D. cell wall

3. Which of a cell's organelles releases energy stored in food?

A. chloroplasts

B. lysosomes

C. endoplasmic reticulum

D. mitochondria

4. Which type of macromolecule contains high-energy bonds and is used for long-term energy

storage?

A. sugars

B. enzymes

C. proteins

D. lipids

5. Which of the following are reactants in the process of photosynthesis?

A. glucose and water

B. carbon dioxide and oxygen

C. carbon dioxide and water

D. glucose and oxygen

6. During photosynthesis, plant cells take in water (H2O) and carbon dioxide (CO2) and release

oxygen (O2). How is this different from what takes place during aerobic respiration?

A. During aerobic respiration, cells take in O2 and release CO2, H2O, and ATP.

B. During aerobic respiration, O2 is inhaled and CO2 and H2O are exhaled.

C. During aerobic respiration, cells use ATP to convert insulin into glucose and CO2.

D. During aerobic respiration, the mitochondria form CO2 during the process of fermentation.

7. During cellular respiration, energy is stored in the form of _______.

A. oxygen

B. ATP

C. water

D. food

8. Examine the picture of the chloroplast below.

Chloroplasts contain flattened disks known as thylakoids that are stacked into grana. In the

thylakoids are proteins that

A. help capture light from the Sun during the process of photosynthesis.

B. help capture light from the Sun during the process of cellular respiration.

C. help capture oxygen from the atomosphere during the process of photosythesis.

D. help capture oxygen from the atmosphere during the process of cellular respiration.

9. What is the function of stomata in plants?

A. to transport materials from the soil to the leaves

B. to allow gas exchange between the environment and the inside of leaves

C. to transport materials from the leaves to the soil

D. to absorb light energy from the Sun

10.

The above illustration shows the molecule used by some cells to temporarily store energy. The

molecule is used in almost all energy-requiring reactions in cells. This molecule could be

considered the "gas" that powers a cell's "engine." What is the name of this molecule?

A. ethyl alcohol

B. adenosine diphosphate

C. adenosine triphosphate

D. glucose

11. During photosynthesis, radiant energy from the Sun is transferred to plants and other

photosynthetic organisms. The chloroplasts in the cells of these organisms then transform the

radiant energy into chemical potential energy stored in the bonds of

A. carbon dioxide.

B. protein molecules.

C. highly condensed carbon compounds, such as carbohydrates.

D. water molecules which then evaporate through openings called stomata.

12. Which of the following organelles convert solar energy into glucose and oxygen?

A. chloroplasts

B. mitochondria

C. endoplasmic reticuli

D. vacuoles

13. Cells obtain energy by either capturing light energy through photosynthesis or by breaking

down carbohydrates through cellular respiration. In both photosynthesis and cellular respiration,

the energy is ultimately derived from the Sun in a

A. highly efficient process which involves no loss of heat to the environment.

B. pathway that involves taking in heat from the environment at each step.

C. one-way process.

D. reversible process.

14.

The above illustration shows the molecule used by some cells to temporarily store energy. The

molecule is used in almost all energy-requiring reactions in cells. This molecule could be

considered the "gas" that powers a cell's "engine." What is the name of this molecule?

A. ethyl alcohol

B. adenosine triphosphate

C. glucose

D. adenosine diphosphate

15. In which organelle does photosynthesis take place?

A. nucleus

B. endoplasmic reticulum

C. chloroplast

D. mitochondrion

16. During photosynthesis, plants capture light energy from the Sun to break weak bonds in

reactants, such as carbon dioxide and water, and form carbon-containing molecules, such as

glucose. The carbon-containing molecules can then be used

A. to assemble larger molecules, such as DNA, proteins, and fats.

B. to produce inorganic compounds, such as sulfuric acid.

C. to synthesize essential amino acids.

D. all of these

17. Organisms undergo many different processes in order to be able to store energy and utilize

that energy. Through which of the following processes is energy released in the form of ATP?

A. cellular respiration

B. phototropism

C. photosynthesis

D. respiration

18. How do cells get energy to perform their necessary functions?

A. Cells get energy by taking in nutrients from food.

B. Cells get energy by moving water from one organelle to another.

C. Cells get energy by dissolving waste products of the body.

D. Cells get energy only by taking in oxygen from the atmosphere.

19. In order to function properly, cells must perform many reactions. Metabolism is the sum of

all the chemical reactions in an organism. During metabolism, ATP

I. is broken down to fuel chemical reactions.

II. is created by chemical reactions.

III. is shuttled from one cell to another.

A. I and II only

B. I and III only

C. III only

D. I, II, and III

20. A plant cell is shown below.

Cellular respiration occurs in the __________.

A. vacuole

B. chloroplast

C. mitochondrion

D. cell wall

21. Examine the picture of the chloroplast below.

Chloroplasts contain flattened disks known as thylakoids that are stacked into grana. In the

thylakoids are proteins that

A. help capture light from the Sun during the process of photosynthesis.

B. help capture oxygen from the atmosphere during the process of cellular respiration.

C. help capture oxygen from the atomosphere during the process of photosythesis.

D. help capture light from the Sun during the process of cellular respiration.

22. Photosynthesis is carried out by which of the following?

A. all living organisms

B. bacteria, but neither animals nor plants

C. plants, but not animals

D. animals, but not plants

23. Adenosine triphosphate, or ATP, is primarily used as _______ in living organisms.

A. a muscle relaxing hormone

B. a source of energy

C. a blood coagulant

D. a reproductive enzyme

24. Which of the following is true about plants and cellular energy?

A. Plants use light energy to produce food molecules during cellular respiration, and obtain

cellular energy from the bonds of these food molecules during photosynthesis.

B. Plants can both use light energy to produce food molecules and obtain cellular energy

from the bonds of these food molecules during photosynthesis.

C. Plants use light energy to produce food molecules during photosynthesis, and obtain

cellular energy from the bonds of these food molecules during cellular respiration.

D. Plants can both use light energy to produce food molecules and obtain cellular energy

from the bonds of these food molecules during cellular respiration.

25.

In the respiration-photosynthesis cycle shown above, what are the reactants of photosynthesis

that belong in box 2?

A. glucose and oxygen

B. ATP and methane

C. protein and nucleic acids

D. carbon dioxide and water

26. Through the process of hydrolysis, cells remove phosphate groups from molecules of ATP to

form molecules of ADP.

This hydrolytic reaction results in

A. the formation of high-energy bonds to store free energy.

B. the breaking of low-energy bonds to produce free energy.

C. the breaking of high-energy bonds to produce free energy.

D. the formation of low-energy bonds to store free energy.

27. During photosynthesis, radiant energy from the Sun is transferred to plants and other

photosynthetic organisms. The chloroplasts in the cells of these organisms then transform the

radiant energy into chemical potential energy stored in the bonds of

A. carbon dioxide.

B. water molecules which then evaporate through openings called stomata.

C. protein molecules.

D. highly condensed carbon compounds, such as carbohydrates.

28. A chloroplast is a type of plastid that is involved in the transformation of energy within a cell

because this is the organelle in which

A. starches are stored.

B. cellular respiration occurs.

C. genetic material is stored.

D. photosynthesis occurs.

29. During the process of photosynthesis, plants use energy from the Sun to convert carbon

dioxide and water into glucose and oxygen. These products are, in turn, used by the plant or

animals that eat the plant during cellular respiration to produce ATP.

ATP molecules store cellular energy. When phosphate groups are removed and molecules of

ADP are formed, energy is released. This energy can be used to perform

A. electron transport.

B. cellular work.

C. osmosis.

D. diffusion.

30. During cellular respiration, the bonds of food molecules are broken, so energy can be

released to fuel other cellular processes. In order for this to occur, which of the following

statements must be true?

A. New compounds with lower-energy bonds must be formed when the high-energy bonds in

food molecules are broken.

B. The energy in the new compounds that are formed must be equal to the energy in the

bonds of the food molecules.

C. New compounds with higher-energy bonds must be formed when the low-energy bonds in

food molecules are broken.

D. The new compounds that are formed must be more complex than the food molecules that

were broken down.

Answers

1. B

2. B

3. D

4. D

5. C

6. A

7. B

8. A

9. B

10. C

11. C

12. A

13. C

14. B

15. C

16. A

17. A

18. A

19. A

20. C

21. A

22. C

23. B

24. C

25. D

26. C

27. D

28. D

29. B

30. A

Explanations

1. There is a one-way flow of energy from the Sun to all of the organisms in an ecosystem.

Energy flows first into the lowest trophic level of an ecosystem via photosynthesis. Carbohydrate

products from photosynthesis are then broken down to liberate energy through cellular

respiration. Heat is lost to the environment at each step during energy transfer through the

ecosystem.

2. Chloroplasts are organelles used by plant cells to make a sugar called glucose from sunlight.

Energy stored in the chemical bonds of the sugar molecules can be used, either by the plants or

by the animals that eat them, to fuel body processes.

Because plants make their own food, they make up the first (and most important) trophic level in

the energy pyramids of terrestrial ecosystems. Some microorganisms, called phytoplankton, also

have chloroplasts. These organisms form the first trophic level in marine ecosystems.

3. Mitochondria are often referred to as the main power source of a cell. That is because of

mitochondria's ability to break down glucose and other food molecules to produce energy. The

energy released by mitochondria is stored in an ATP molecule.

Without mitochondria, cells would not be able to generate energy to perform cellular work, and

cellular death would be the result.

4. Lipids are macromolecules used by the body for long-term energy storage. Lipids, like sugars,

are composed primarily of carbon, hydrogen, and oxygen. They contain high-energy bonds that

can be broken by cells to release energy to do cell work.

Sugars contain high-energy bonds, but are used by the body for short-term energy storage.

5. The process of photosynthesis can be generally expressed by:

carbon dioxide + water + light → glucose + oxygen

So, the reactants in photosynthesis are carbon dioxide and water.

6. During aerobic respiration, glucose is broken down in a cell's mitochondria. The products that

result from the breakdown of glucose include carbon dioxide, water, and energy.

C6H12O6 (glucose) + 6 O2 (oxygen)

6 CO2 (carbon dioxide) + 6 H2O (water) + ATP (energy)

Therefore, aerobic respiration is different from photosynthesis because during aerobic

respiration, cells take in O2 and release CO2, H2O, and ATP.

7. During aerobic respiration, cells use oxygen to release the energy stored in glucose. This

energy is temporarily stored in the form of ATP (adenosine triphosphate), and water and carbon

dioxide are released as wastes.

8. Chloroplasts are mainly found in plants. In the chloroplasts are stacks of flattened disks that

contain proteins that help capture light from the Sun during the process of photosynthesis.

9. On the underside of leaves, pairs of guard cells create microscopic pores called stomata. These

allow for the exchange of gases between the environment and the interior cells. This gas

exchange is vital to plant cell photosynthesis, which requires carbon dioxide gas as a reactant. In

addition, excess oxygen created as a product is removed through stomata.

10. When adenosine binds with two phosphate molecules, it is known as adenosine diphosphate

(di meaning 2). With three phosphate molecules, it is adenosine triphosphate (tri meaning 3).

Cells use ATP (Adenosine TriPhosphate) to temporarily store energy. When the cell is in need of

energy, a reaction occurs in which the ATP becomes ADP (Adenosine DiPhosphate) and energy

is released.

11. Chloroplasts in photosynthetic organisms convert radiant energy from the Sun into

condensed carbon compounds such as carbohydrates. The plants then either convert these

carbohydrates into structural or storage materials, or use them to generate ATP for cellular

processes.

12. In chloroplasts, organelles only found in autotrophs, such as plants, algae, and cyanobacteria,

carbon dioxide and water are transformed into glucose and oxygen when solar energy excites

electrons in chlorophyll.

13. There is a one-way flow of energy from the Sun to all of the organisms in an ecosystem.

Energy flows first into the lowest trophic level of an ecosystem via photosynthesis. Carbohydrate

products from photosynthesis are then broken down to liberate energy through cellular

respiration. Heat is lost to the environment at each step during energy transfer through the

ecosystem.

14. When adenosine binds with two phosphate molecules, it is known as adenosine diphosphate

(di meaning 2). With three phosphate molecules, it is adenosine triphosphate (tri meaning 3).

Cells use ATP (Adenosine TriPhosphate) to temporarily store energy. When the cell is in need of

energy, a reaction occurs in which the ATP becomes ADP (Adenosine DiPhosphate) and energy

is released.

15. Photosynthetic pigments, which absorb and convert light energy into chemical energy, are

embedded in the membranous structure of chloroplasts in plant cells. These pigments give

chloroplasts, and plants, their characteristic green color because they absorb all colors of the

visible spectrum except green. Once light energy is converted into a chemical form, enzymes

present inside chloroplasts can use this energy to synthesize fuel storage molecules like glucose

and starch.

16. The cellular processes of photosynthesis and respiration involve the transformation of matter

and energy.

Carbon-containing molecules, such as glucose, that are formed as a product of photosynthesis

can be used to assemble larger molecules, such as DNA, proteins, and fats.

Furthermore, energy that is released when these molecules react with oxygen during cellular

respiration can be used to fuel other life processes.

17. Energy in the form of ATP is then released during cellular respiration.

The process of cellular respiration can be generally expressed by:

glucose + oxygen → carbon dioxide + water + ATP

The cycling of energy and mass through the processes of photosynthesis and respiration show

how the mass and energy of the reactants in a biochemical process can be transferred into the

products. However, according to the laws of conservation of mass and energy, the total amount

both remains the same.

18. Cells get energy to perform their necessary functions by taking in nutrients from food.

During the digestive process, nutrients from food are broken down and used to synthesize sugar,

or glucose, molecules. When the glucose is broken down, a lot of energy is created. This energy

is then used for various cell functions.

19. During metabolism, ATP is broken down to fuel chemical reactions, or it can be created

by chemical reactions.

Metabolism is often divided into two main categories - catabolism and anabolism. Catabolism is

the set of chemical reactions that breaks large molecules into smaller units. During catabolic

processes, ATP (energy) is created and released. Anabolism is the set of chemical reactions that

builds large molecules from smaller units. During anabolic processes, ATP (energy) is broken

down and used for fuel.

ATP usually remains in the cell that creates it, so it is not shuttled from cell to cell.

20. Only plants and other photosynthetic organisms, such as phytoplankton, can make sugar

molecules using energy from the Sun. However, plant cells and animals cells use the energy

stored in the bonds of the sugar molecules to fuel cellular processes.

The process in which energy is released from glucose molecules and used to do cellular work is

called cellular respiration. In either plant or animal cells, cellular respiration takes place

primarily in the mitochondria.

21. Chloroplasts are mainly found in plants. In the chloroplasts are stacks of flattened disks that

contain proteins that help capture light from the Sun during the process of photosynthesis.

22. Photoautotrophs are organisms that can perform photosynthesis, a pathway that converts the

energy from sunlight into the chemical energy of organic molecules. These molecules can then

store the collected energy for later use when needed. Land plants, algae, and some kinds of

bacteria are photoautotrophs, but animals cannot use light energy. They require an input of

energy that is already in an organic molecule form (i.e. food).

23. ATP is a high-energy molecule composed of a purine base (adenine), a five-carbon sugar

(ribose), and three phosphate groups. It is primarily used as a source of energy in living

organisms.

ATP supplies energy to every endergonic reaction that occurs in the body. For example, the

energy from ATP can be used by the organism to obtain, transform, and transport materials, and

to eliminate wastes.

24. Photosynthesis is the process by which organisms, such as green plants, use light energy to

produce food. Cellular respiration is the process by which living things, including both plants

and animals, obtain energy from the bonds of food molecules. Therefore, plants use light

energy to produce food molecules during photosynthesis, and obtain cellular energy from

the bonds of these food molecules during cellular respiration.

25. The processes of photosynthesis and cellular respiration are interdependent. The products of

one process act as the starting materials, or reactants, of the other process.

Photosynthesis produces glucose and oxygen. These products are used as reactants in the process

of aerobic respiration. Aerobic respiration produces carbon dioxide and water. These products

are used as reactants in the process of photosynthesis.

26. Adenosine triphosphate, or ATP, is a macromolecule used by the body for energy storage.

ATP contains adenine, ribose, and three phosphate groups. Each of the phosphate bonds stores a

large quantity of energy which is released for use when the bond is broken.

When this reaction occurs in reverse, cells perform dehydration reactions to add phosphate

groups to ADP and store energy for later use.

27. Chloroplasts in photosynthetic organisms convert radiant energy from the Sun into

condensed carbon compounds such as carbohydrates. The plants then either convert these

carbohydrates into structural or storage materials, or use them to generate ATP for cellular

processes.

28. Plastids are membrane-bound organelles that can be found in plant and algae cells. In plants,

these organelles can differentiate into various forms to play different roles within the cell.

A chloroplast is a type of plastid that is involved in the transformation of energy within a cell

because this is the organelle in which photosynthesis occurs. Other plastids perform different

functions. For example, amyloplasts are used to store starch; chromoplasts are used for pigment

synthesis and storage; and elaioplasts store fats within the cell.

29. When a phosphate group is removed from a molecule of ATP, a molecule of ADP is formed.

Energy is released, so it can be used to perform cellular work, such as obtaining, transforming,

or transporting materials and eliminating wastes.

30. The cellular processes of photosynthesis and respiration involve the transformation of matter

and energy.

According to the law of conservation of energy, energy can neither be created nor destroyed. So,

in order to obtain excess energy to fuel cellular processes, the bonds formed in the new

compounds must have less energy than the bonds in the original food molecules.