What Is Life? A Guide to Biology

Jay Phelan

Chapter 4

Energy - all with Video Answers

Educators

Chapter Questions

Problem 1

Animal fats and plant oils are sometimes used as sources of fuel for automobile engines. How is energy harvested from these molecules?
a) They contain long chains of hydrogen and carbon that, when broken, release the energy stored in the bonds linking the atoms together.
b) They contain hydrogen and carbon tails linked by disulfide bridges that, when broken, release chemical energy.
c) They contain multiple phosphate groups that each release energy when "liberated" from the molecule chemically.
d) They contain long hydrophobic regions that, when mixed with water, generate explosive resistances.
e) They contain long carbon tails, and each atom has unpaired electrons that are released on exposure to extreme heat and pressure

Dennis Howard

Dennis Howard

Numerade Educator

Problem 2

A cyclist rides her bike up a very steep hill. Pick from the flowing choices the statement that properly describes this activity in energetic terms.
a) Potential energy in food is converted to kinetic energy as the cyclist's muscles push her up the hill.
b) Kinetic energy is highest when the cyclist is at the crest of the hill.
c) The cyclist produces the most potential energy as she cruises down the hill's steep slope.
d) Potential energy is greatest when the cyclist is at the top of the hill.
e) Both a) and d) are correct.

Dennis Howard

Numerade Educator

Problem 3

Every time a source of energy is converted from one form to another:
a) the potential energy of the system increases.
b) heat is required.
c) the second law of thermodynamics is violated.
d) the total amount of energy in the universe is reduced by a tiny amount.
e) some of the energy is converted to heat, which is not a very usable form of kinetic energy.

Dennis Howard

Numerade Educator

Problem 4

In your body, when energy is released from the breakdown of a molecule such as glucose:
a) adenosine monophosphate is created.
b) adenosine diphosphate is created.
c) some of the energy may be harnessed by building the unstable high-energy bonds that attach phosphate groups to ADP molecules.
d) molecules of ATP are required to capture and absorb the heat generated by the reaction.
e) all of the energy is lost as heat.

Dennis Howard

Numerade Educator

Problem 5

A green plant can carry out photosynthesis if given nothing more than:
a) water, light, and carbon dioxide.
b) water, light, and oxygen.
c) carbon dioxide.
d) oxygen.
e) oxygen and carbon dioxide.

Dennis Howard

Numerade Educator

Problem 6

The actual production of sugars during photosynthesis takes place:
a) within the outer membrane of the chloroplast.
b) within the stroma, inside the thylakoids of the chloroplast.
c) within the stroma, outside the thylakoid, but still inside the chloroplast.
d) just outside the chloroplast, within the mitochondria.
e) within the thylakoid membrane of the chloroplast.

Dennis Howard

Numerade Educator

Problem 7

The leaves of plants can be thought of as "eating" sunlight. From an energetic perspective, this makes sense because:
a) light energy, like chemical energy released when the bonds of food molecules are broken, is a type of kinetic energy.
b) both light energy and food energy can be converted to kinetic energy without the loss of heat.
c) the carbon-oxygen bonds within a photon of light release energy when broken by the enzymes in chloroplasts.
d) the carbon-hydrogen bonds within a photon of light release energy when broken by the enzymes in chloroplasts.
e) photons are linked together by hydrogen bonds, which release energy when striking the surface of a leaf.

Dennis Howard

Numerade Educator

Problem 8

A molecule of chlorophyll increases in potential energy:
a) when it binds to a photon.
b) when a photon strikes it, boosting electrons to a higher-energy excited state.
c) when it loses an electron.
d) only in the presence of oxygen.
e) None of the above. The potential energy of a molecule cannot change.

Dennis Howard

Numerade Educator

Problem 9

Photosynthesizing plants rely on water:
a) to provide the protons necessary to produce chlorophyll.
b) to concentrate the beams of light hitting a leaf, focusing them on the reaction center.
c) to replenish oxygen molecules that are lost during photosynthesis.
d) to replace electrons that are excited by light energy and passed from molecule to molecule down an electron transport chain.
e) to serve as a high-energy electron carrier.

Dennis Howard

Numerade Educator

Problem 10

During photosynthesis, which step is most responsible for a plant's acquisition of new organic material?
a) the "building" of NADPH during the Calvin cycle
b) the excitation of chlorophyll molecules by photons of light
c) the "plucking" of carbon atoms from the air and fixing of them to organic molecules within the chloroplast
d) the loss of water through evaporation
e) the production of ATP during the light reactions

Dennis Howard

Numerade Educator

Problem 11

During C4 photosynthesis:
a) plants use less ATP when producing sugar.
b) plants are able to continue producing sugars even when they must close their stomata to reduce water loss on hot days.
c) plants are able to generate water molecules to cool their leaves.
d) plants are able to reduce water loss by producing more rubisco.
e) plants are able to produce sugars without any input of carbon dioxide.

Dennis Howard

Numerade Educator

Problem 12

Cellular respiration is the process by which:
a) oxygen is used to transport chemical energy throughout the body.
b) oxygen is produced during metabolic activity.
c) light energy is converted to kinetic energy.
d) ATP molecules are converted to water and sugar.
e) energy from the chemical bonds of food molecules is captured by an organism.

Dennis Howard

Numerade Educator

Problem 13

During cellular respiration, most of the energy contained within the bonds of food molecules is captured in:
a) the conversion of the kinetic energy of food to the potential energy of ATP.
b) the Krebs cycle and electron transport chain.
c) digestion.
d) glycolysis.
e) None of the above. Energy is lost, not gained, during cellular respiration.

Dennis Howard

Numerade Educator

Problem 14

Which of the following energy-generating processes is the only one that occurs in all living organisms?
a) the Krebs cycle
b) glycolysis
c) combustion
d) photosynthesis
e) None of the above. There are no energy-generating processes that occur in all living organisms.

Dennis Howard

Numerade Educator

Problem 15

During the Krebs cycle:
a) the products of glycolysis are further broken down, generating additional ATP and the high-energy electron carrier NADH.
b) high-energy electron carriers pass their energy to molecules of sugar, which store them as potential energy.
c) the products of glycolysis are further broken down, generating additional ATP and ethanol.
d) cellular respiration can continue even in the absence of oxygen.
e) the products of glycolysis are converted to acetyl-CoA.

Dennis Howard

Numerade Educator

Problem 16

Mitochondria have a "bag within a bag" structure. This structure is necessary in order to:
a) create a concentration gradient of certain molecules between the regions inside and outside the "inner bag," a form of potential energy.
b) keep molecules of ADP in close proximity to molecules of the ATP-synthesizing enzyme.
c) allow light-reactive accessory pigments to be embedded within the membranes.
d) segregate the most toxic digestive enzymes from molecules of ATP and NADP'.
e) None of the above.

Dennis Howard

Numerade Educator

Problem 17

All alcoholic beverages are produced as the result of:
a) cellular respiration by bacteria that occurs in the absence of oxygen.
b) cellular respiration by bacteria that occurs in the absence of free electrons.
c) cellular respiration by yeast that occurs in the absence of free electrons.
d) cellular respiration that occurs in the absence of sugar.
e) cellular respiration by yeast that occurs in the absence of oxygen.

Dennis Howard

Numerade Educator

Problem 18

In harvesting the chemical energy of the molecules in food:
a) all macromolecules must first be converted to glucose.
b) all macromolecules must first be converted to their hydrocarbon chains.
c) all macromolecules must first be converted to glucose or another simple sugar.
d) organisms can use sugars, lipids, and proteins.
e) all macromolecules must first be converted to proteins or free-form amino acids.

Dennis Howard

Numerade Educator