Exam 2

Question 1

Which of the following represents kinetic energy?

a. The flow of hydrogen ions (H+) through ATP synthase and the phosphorylation of ADP to form ATP
b. A concentration gradient across a membrane
c. An electric charge imbalance across a membrane
d. Both A and B
e. All of the above

Answer 1

A

Question 2

The sum total of all the anabolic and catabolic reactions in a living cell is called its

a. energetics.
b. activity.
c. metabolism.
d. entropy.
e. respiration.

Answer 2

C

Question 3

Which term most precisely describes the cellular process of making higher energy molecules out of lower energy ones?

a. catalysis
b. metabolism
c. anabolism
d. condensation
e. catabolism

Answer 3

C

Question 4

How does the first law of thermodynamics apply to organisms?

a. As energy transformations occur, free energy is transferred from one form to another, it is neither created nor destroyed.
b. To maintain order, life requires a balance of energy.
c. The potential energy of ATP is converted to kinetic energy such as muscle contractions but also releases heat.
d. Reactions occur only with a release of energy.
e. It does not apply to organisms; the complexity of organisms contradicts the first law.

Answer 4

A

Question 5

During photosynthesis, plants capture only about 5% of the energy available in sunlight and convert it into the potential energy found in glucose. This inefficiency in energy transfer is an example of?
a. negative free energy (-ΔG).
b. chemical equilibrium.
c. the first law of thermodynamics.
d. the second law of thermodynamics.
e. a spontaneous reaction.

Answer 5

D

Question 6

In any system, the total energy includes usable and unusable energy. The usable energy is referred to as

a. free energy.
b. entropy.
c. heat.
d. thermodynamics.
e. equilibrium.

Answer 6

A

Question 7

If ΔG of a chemical reaction is positive, you can conclude that it…
a. releases energy.
b. is endergonic.
c. is exergonic.
d. will not reach equilibrium.
e. increases the disorder in the system.

Answer 7

B

Question 8

The mathematical expression for the free change in free energy of a system is ΔG=ΔH-T ΔS. Which of the following is (are) correct?

a. ΔS is the change in entropy
b. ΔH is the change in free energy
c. ΔG is a change in the enthalpy
d. T is the temperature
e. Answers A and D are correct

Answer 8

E

Question 9

Which of the following statements about enzymes is false?
a. An enzyme changes shape when it binds to a substrate.
b. Enzymes lower the activation energy.
c. Enzymes can only catalyze a certain number of reactions before they are completely consumed.
d. An enzyme may orient substrates, induce strain, or temporarily add chemical groups.
e. Most enzymes are much larger than their substrates.

Answer 9

C

Question 10

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?
a. The change in free energy of the reaction is positive.
b. Room temperature does not achieve the necessary energy of activation for the reaction to occur.
c. The change in free energy of the reaction is negative.
d. This is a condensation reaction.
e. The free energy of the products is higher than the free energy of the reactants.

Answer 10

B

Question 11

In some cases, a substrate–enzyme complex is stabilized by
a. hydrogen bonds.
b. covalent bonds.
c. ionic attractions.
d. hydrophobic interactions.
e. all of the above

Answer 11

E

Question 12

Which of the following could denature an enzyme?
a. high temperature
b. changes in pH.
c. an allosteric regulator
d. answers A and B are correct
e. all of the above are correct

Answer 12

D

Question 13

Why is ATP an important molecule in metabolism?
a. Its hydrolysis provides an input of free energy for endergonic reactions.
b. Its terminal phosphate groups ionize easily, releasing free energy.
c. It transfers (couples) free energy between exergonic and endergonic reactions.
d. Answers A and B are correct
e. All of the above are correct

Answer 13

E

Question 14

Many enzymes require NAD+ and NADH for a reaction to occur. They temporarily bind to and then release from the substrate to participate in other reactions. NAD+ and NADH are considered
a. a side chain.
b. a coupled reaction
c. coenzymes
d. a prosthetic group.
e. cofactors.

Answer 14

C

Question 15

Four atoms of ferrous Iron (Fe) are required for hemoglobin protein to efficiently carry oxygen in the human bloodstream. The iron most likely functions as a(n)
a. cofactor necessary for enzyme activity
b. noncompetitive inhibitor of the enzyme.
c. allosteric activator of the enzyme.
d. competitive inhibitor of the enzyme.
e. coenzyme necessary for moving hydrogen ions from one pathway to another.

Answer 15

A

Question 16

How do competitive and noncompetitive enzyme inhibitors differ?
a. They function at different pH values.
b. Competitive inhibitors have a higher energy of activation than noncompetitive inhibitors have.
c. Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors change the shape of the active site.
d. Noncompetitive enzyme inhibitors contain magnesium, whereas competitive inhibitors contain iron.
e. Noncompetitive enzyme inhibitors are reversible, whereas competitive inhibitors are irreversible.

Answer 16

C

Question 17

An allosteric inhibitor
a. decreases the concentration of the enzyme.
b. changes the shape of a substrate.
c. increases the concentration of a product.
d. changes the shape of an enzyme (the shape of its active site).
e. increases the concentration of an enzyme–substrate complex.

Answer 17

D

Question 18

The process that involves an end product acting as an inhibitor of an earlier step in a metabolic pathway is called
a. feedback inhibition.
b. feedback activation.
c. positive feedback.
d. concerted activation.
e. competitive inhibition.

Answer 18

A

Question 19

When organisms move from one environment to another, they sometimes synthesize variations of existing enzymes, which are called
a. coenzymes.
b. isozymes.
c. abzymes.
d. effectors.
e. activators.

Answer 19

B

Question 20

Consider the pathway below, if product F is an allosteric inhibitor of enzyme 3, what will be the result as F accumulates?

a. The concentration of product C will decrease.
b. The concentration of reactants A and B will increase.
c. The concentration of product E will increase because more of F is converted back to E.
d. The concentration of product D will increase.
e. The concentration of products E and F will both increase.

Answer 20

D

Question 21

You are studying a new species. It lives in freshwater hot springs where the water temperature averages 50°C to 60°C. You determine that it has a surface enzyme that catalyzes a reaction leading to its protective coating, and you decide to study this enzyme in the laboratory. Under what conditions would you most likely find optimal activity of this enzyme?
a. 0°C
b. 37°C
c. 55°C
d. 95°C
e. 105°C

Answer 21

C

Question 22

Which of the following statements about metabolic pathways is false?
a. The product of one reaction becomes the reactant for the next reaction.
b. They are a series of enzyme-catalyzed reactions.
c. Many are compartmentalized in eukaryotes.
d. Many are highly conserved even between organisms in different domains of life
e. Almost all are catabolic.

Answer 22

E

Question 23

When NADH gives two electrons to complex I of the respiratory electron transport system, NADH is
a. reduced.
b. oxidized.
c. phosphorylated.
d. aerobic.
e. hydrolyzed.

Answer 23

B

Question 24

When electrons move closer to a more electronegative atom, what happens?
a. Free energy is released.
b. Free energy is consumed.
c. Atoms are ionized.
d. Atoms become chemically inert or “noble”.
e. A and C are correct.

Answer 24

A

Question 25

In all cells, glucose catabolism begins with
a. the citric acid cycle
b. fermentation.
c. pyruvate oxidation to acetyl CoA.
d. glycolysis.
e. chemosmosis.

Answer 25

D

Question 26

NAD+
a. is a key electron carrier in redox reactions.
b. is an amino acid class of biological molecule.
c. requires oxygen to function.
d. answer A and B are correct.
e. all of the above are correct

Answer 26

A

Question 27

Which of the following processes occurs during aerobic respiration?
a. Pyruvate oxidation to acetyl-CoA
b. The citric acid cycle
c. Fermentation
d. Answers A and B are correct
e. All of the above

Answer 27

D

Question 28

Which of the following is an intermediate of the citric acid cycle?
a. pyruvate.
b. glucose-6-phosphate
c. oxaloacetate
d. phosphoenol pyruvate
e. 3-phosphoglyceric acid

Answer 28

C

Question 29

Substrate-level phosphorylation is the enzymatic transfer of a phosphate from an organic molecule to?
a. another enzyme.
b. ADP
c. ATP.
d. NAD+
e. a carbohydrate.

Answer 29

B

Question 30

The pyruvate dehydrogenase complex (pyruvate oxidation) generates
a. CO2
b. NADH + H+ from NAD+.
c. glucose-6-phosphate
d. answer A and B are correct
e. all of the above are correct

Answer 30

D

Question 31

Which of the following is produced/generated during the citric acid cycle?
a. NADH and FADH2
b. 3-phosphoglycerate
c. Lactic acid
d. Pyruvate
e. Glucose-6-phosphate

Answer 31

A

Question 32

Animals breathe in air containing oxygen and breathe out air with less oxygen and more carbon dioxide. The carbon dioxide comes from
a. pyruvate oxidation to acetyl-CoA.
b. the citric acid cycle.
c. glycolysis.
d. answers A and B are correct
e. All of the above are correct

Answer 32

D

Question 33

You have a friend who lost 7 kg (about 15 pounds) of fat on a diet. How did that matter leave their body?
a. Chemical energy was converted to heat and then released.
b. Most was converted to muscle and muscle weighs less than fat.
c. Most was converted to ATP, which weighs much less than fat.
d. Most was released as CO2 and H2O.
e. Most was converted to feces and eliminated from the body.

Answer 33

D

Question 34

During aerobic respiration in the eukaryotic cell, H+ ions accumulate where?
a. nucleus.
b. endoplasmic reticulum
c. mitochondrial intermembrane space.
d. mitochondrial matrix
e. cytosol.

Answer 34

C

Question 35

Which of the following statements about the respiratory electron transport chain is FALSE?
a. Electrons are received from NADH and FADH2.
b. Electrons are passed from donor to recipient carrier molecules in a series of oxidation–reduction reactions.
c. In humans, the terminal electron acceptor is pyruvate.
d. Most of the enzymes are part of the inner mitochondrial membrane.
e. It contains Cytochromes and Ubiquinone (Coenzyme Q).

Answer 35

C

Question 36

Human infants and hibernating animals have specialized “brown fat” cells that produce a protein called Thermogenin. This protein releases the H+ ion gradient created by the respiratory electron transfer chain. Which of the following statements regarding “brown fat” cells is/are TRUE?
a. Oxygen would no longer be reduced to water during respiration.
b. No ATP would be made.
c. The citric acid cycle would eventually stop functioning as all available NAD+ became reduced.
d. The cells would generate large amounts of heat.
e. Hibernating animals increasingly rely on fermentation pathways for energy

Answer 36

D

Question 37

The component of aerobic respiration that produces the most ATP per mole of glucose is
a. glycolysis
b. the citric acid cycle.
c. the electron transport chain and oxidative phosphorylation.
d. lactic acid fermentation.
e. alcoholic fermentation.

Answer 37

C

Question 38

Which of the following statements regarding the formation of lactate by human cells is/are TRUE
a. it is an example of fermentation.
b. it recycles NAD+ from NADH
c. it produces CO2
d. answer A and B are true
e. all of the above are true

Answer 38

D

Question 39

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, an early step of glycolysis. An increased accumulation of citrate (an allosteric regulator of PFK) would be expected to…
a inhibit the enzyme and slow the rates of glycolysis and the citric acid cycle.
b activate the enzyme and slow the rates of glycolysis and the citric acid cycle.
c. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
d. activate the enzyme and increase the rates of glycolysis and the citric acid cycle.
e. citrate would have no effect on the rates of glycolysis and the citric acid cycle.

Answer 39

A

Question 40

Which hormone is deficient (absent) in humans with Type I (juvenile) diabetes?
a. oxaloacetate
b. insulin
c. thyroxin
d. peptidase
e. glucose levelase

Answer 40

B

Question 41

Which of the following are benefits of exercise in humans?
a. improves LDL to HDL ratio
b. uses calories
c. increases bone mass and muscle tone
d. answers A and B are correct
e. all of the above are correct

Answer 41

E

Question 42

Plants are green because
a. plants do not possess green pigment.
b. chlorophylls absorb blue and orange-red wavelengths of light and reflect green light.
c. energized chlorophyll a emits green light.
d. chloroplasts hydrolyze ATP to produce green light.
e. chlorophylls absorb green light.

Answer 42

B

Question 43

The main photosynthetic pigments in plants are _______ and _______.
a. chlorophyll a; chlorophyll b
b. chlorophyll x; chlorophyll y
c. retinal pigment; accessory pigment
d. caratonoids and phycobilins
e. None of the above

Answer 43

A

Question 44

Accessory pigments
a. play no role in photosynthesis.
b. transfer energy from chlorophyll to the electron transport chain.
c. absorb only the red wavelengths.
d. allow plants to absorb visible light of varying wavelengths.
e. transfer electrons to NADP.

Answer 44

D

Question 45

Which of the following gives up electrons during noncyclic photophosphorylation (light dependent reactions)?
a. CO2
b. water (H2O)
c. ATP
d. O2 gas
e. None of the above

Answer 45

B

Question 46

The net energy outcome of noncyclic photophosphorylation (light dependent reactions) is
a. ATP.
b. ATP and NADH.
c. NADPH.
d. ATP and NADPH.
e. sugar.

Answer 46

D

Question 47

Which of the following occurs during the light-independent (dark or calvin-benson) reactions of photosynthesis?
a. ATP and NADPH are recycled back to ADP and NADP+.
b. CO2 is converted into organic molecules (glyceraldehydes-3-phosphate).
c. Water is converted into hydrogen and oxygen.
d. Answers A and B are correct
e. All of the above are correct

Answer 47

D

Question 48

Where would you find photosytem II in a green plant?
a. the stroma of a chloroplast
b. the thylakoid membrane of a chloroplast
c. the cytoplasmic membrane
d. the cytosol
e. the mitochondrial inner membrane

Answer 48

B

Question 49

If you were to grow a green plant in a lighted chamber in the presence of radioactive carbon dioxide for several minutes only, which of the following types of compounds in the plant would be radioactive?
a. Only sugars
b. Amino acids and proteins
c. Oils and membrane lipids
d. Calvin cycle intermediates
e. All of the above

Answer 49

D

Question 50

During sunny dry days, photorespiration may occur in plants. During photorespiration, the enzyme rubisco uses _______ as a substrate.
a. O2
b. CO2
c. glyceraldehyde 3-phosphate
d. 3-phosphoglycerate
e. NADPH

Answer 50

A