Exam 2

Question 1

If the free energy of X = +10.0, the following apply to the coupled reaction

Answer 1

the coupled reaction will represent an endergonic reaction

Question 2

If the free energy of X = +2.4, the following apply to the coupled reaction

Answer 2

the coupled reaction will occur

Question 3

The lock-and-key analogy for enzymes applies to the specificity of enzymes

Answer 3

) binding to their substrate

Question 4

Which of the following is most similar in structure to ATP?

Answer 4

an RNA nucleotide

Question 5

Which of the following statements is most true?

A) consist of a hydrophilic head and two hydrophobic tails
B) self-assemble into a bilayer
C) are the major component of all cell membranes
D) amphipathic molecule
E) all of the above

Answer 5

E!

Question 6

Which of these molecules is most easily able to pass through the lipid bilayer via passive diffusion?

Answer 6

H2O

Question 7

The following mechanisms of endocytosis are utilized by cells:

Answer 7

receptor-mediated endocytosis

Question 8

Phospholipids have the following characteristics

A) consist of a hydrophilic head and two hydrophobic tails
B) self-assemble into a bilayer
C) are the major component of all cell membranes
D) amphipathic molecule
E) all of the above

Answer 8

E!

Question 9

Which of the following types of reactions would decrease the entropy within a cell?

Answer 9

B) anabolic reactions

Question 10

) For living organisms, which of the following is an important consequence of the first law of thermodynamics?

Answer 10

D) the organism ultimately must obtain all of the necessary energy for life from its environment

Question 11

Which of these processes require energy (ATP)?

A) diffusion
B) osmosis
C) facilitated diffusion
D) active transport
E) none of the above

Answer 11

Active Transport

Question 12

Reactants capable of interacting to form products in a chemical reaction
must first overcome a thermodynamic barrier known as the reaction’s

Answer 12

activation energy

Question 13

A noncompetitive inhibitor decreases the rate of an enzyme reaction by

A) binding at the active site of the enzyme
B) changing the free energy change of the reaction
C) acting as a coenzyme for the reaction
D) changing the shape of the enzyme’s active site
E) none of the above

Answer 13

D changing the shape of the enzymes active site

Question 14

According to the fluid mosaic model of cell membranes, phospholipids _____.
A) frequently flip-flop from one side of the membrane to the other
B) can move laterally along the plane of the membrane
C) have hydrophilic tails in the interior of the membrane
D) occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane
E) none of the above

Answer 14

B can move laterally along the plane of the mebrane

Question 15

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the
result is the
A) formation of ATP
B) reduction of NAD+
C) restoration of the NA+/K+ balance across the membrane
D) creation of a proton gradient
E) lowering of pH in the mitochondrial matrix

Answer 15

D creation of a proton gradient

Question 16

The key enzyme which regulates glycolysis through allosteric binding of ATP and its products is:
A) hexokinase
B) ATP synthase
C) rubisco
D) coenzyme A
E) none of the above

Answer 16

E. none of the above
pyruvate kinase

Question 17

Energy in the form of ATP is initially invested during
A) citric acid cycle
B) oxidative phosphorylation
C) alcohol fermentation
D) lactic acid fermentation
E) none of the above

Answer 17

E none of the above

the first half of glycolysis

Question 18

Which of the following occurs in the mitochondria of a
eukaryotic cell?
A) glycolysis
B) fermentation
C) Calvin cycle
D) light reactions
E) none of the above

Answer 18

E none of the above
oxidative phosphorylation

Question 19

Which of the listed statements describes the results of the
following reaction?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

A) O2 is reduced and CO2 is oxidized
B) C6H12O6 is oxidized and O2 is reduced
C) O2 is oxidized and H2O is reduced
D) CO2 is reduced and O2 is oxidized
E) none of the above

Answer 19

B C6H12O6 is oxidized and O2 is reduced

Question 20

) During aerobic respiration, electrons travel downhill in which sequence?
A) glucose  pyruvate  ATP  oxygen
B) food  NADH  electron transport chain  oxygen
C) glucose  ATP  electron transport chain  NADH
D) food  citric acid cycle  ATP  NAD+
E) food  glycolysis  citric acid cycle  NADH  ATP

Answer 20

B food  NADH  electron transport chain  oxygen

Question 21

What is the primary function of the Calvin Cycle?
A) use ATP to release carbon dioxide
B) use NADPH to release carbon dioxide
C) synthesize simple sugars from carbon dioxide
D) split water and release oxygen
E) transport RuBP out of the chloroplast

Answer 21

C synthesize simple sugars from carbon dioxide

Question 22

The primary role of oxygen in cellular respiration is to
A) catalyze the reactions of glycolysis
B) combine with carbon, forming CO2
C) combine with lactate, forming pyruvate
D) act as an acceptor for electrons and hydrogen, forming water
E) yield energy in the form of ATP as it is passed down the respiratory chain

Answer 22

D act as an acceptor for electrons and hydrogen, forming water

Question 23

A chemical reaction that has a positive ∆G is best described as _____.
A) endergonic
B) enthalpic
C) exergonic
D) spontaneous
E) none of the above

Answer 23

A endergonic

Question 24

Which of the following is true for anabolic pathways?
A) they are usually highly spontaneous chemical reactions
B) they consume energy to build up polymers from monomers
C) they release energy as they degrade polymers to monomers
D) they do not depend on enzymes
E) none of the above

Answer 24

B they consume energy to build up polymers form monomers

Question 25

Which of the following molecules would likely move through the lipid bilayer of a plasma membrane?
A) glucose
B) Na+
C) O2
D) Cl-
E) none of the above

Answer 25

C O2

Question 26

9) The presence of cholesterol in the plasma membranes of some animals
A) enables the membrane to stay fluid more easily when cell temperature drops.
B) enables the animal to remove hydrogen atoms from saturated phospholipids.
C) enables the animal to add hydrogen atoms to unsaturated phospholipids.
D) makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.
E) makes the animal more susceptible to circulatory disorders

Answer 26

A enables the membrane to stay fluid more easily when the cell temperature drops

Question 27

Which of the following membrane activities require energy from ATP hydrolysis?
A) facilitated diffusion
B) movement of water into a cell
C) Na+

ions moving out of the cell
D) movement of glucose molecules
E) movement of water into a paramecium

Answer 27

C Na+ ions moving out of the cell

Question 28

17) During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
A) transferred to ADP, forming ATP
B) transferred directly to ATP
C) retained in the pyruvate
D) stored in the NADP produced
E) used to phosphorylate fructose to form fructose-6-phosphate

Answer 28

C retained in pyruvate

Question 29

P680+
is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
A) It transfers its electrons to reduce NADP+ to NADPH.
B) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than
oxygen has.
C) It is the receptor for the most excited electron in either photosystem of photosynthesis.
D) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.
E) none of the above

Answer 29

It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than
oxygen has.

Question 30

The citric acid cycle oxidizes organic food derived from
A) NADH
B) ATP
C) pyruvate
D) Coenzyme A
E) Acetyl CoA

Answer 30

C and E pyruvate and acetyl CoA

Question 31

29) Gene therapy is a possible new way to treat many diseases,
including cancer, by turning genes back on. In cancer, a gene for which
type of protein would you most likely want to turn back on to end a signal
cascade?
A) phosphatase protein
B) transcription factor protein
C) kinase protein
D) intracellular receptor protein
E) none of the above

Answer 31

A phosphatase protein

Question 32

If the free energy of X = +8.0, the following apply to the coupled reaction
A) the coupled reaction will occur
B) the coupled reaction will represent an endergonic reaction
C) the coupled reaction will be spontaneous
D) the coupled reaction will represent an exergonic reaction
E) none of the above

Answer 32

B the couple reaction will represent an endergonic reaction

Question 33

38) If the free energy of X = +3.3, the following apply to the coupled reaction
A) the coupled reaction will occur
B) the coupled reaction will represent an endergonic reaction
C) the coupled reaction will be non-spontaneous
D) more information is needed to determine the outcome for the reaction
E) none of the above

Answer 33

A the coupled reaction will occur

Question 34

Which of the following processes is most directly driven by light energy?
A) reduction of NADP+ molecules
B) carbon fixation in the stroma
C) removal of electrons from chlorophyll molecules
D) creation of a pH gradient by pumping protons across the thylakoid membrane
E) none of the above

Answer 34

C removal of electrons from chlorophyll molecules

Question 35

In photosynthetic cells, synthesis of ATP by chemiosmosis occurs during ________.
A) photosynthesis only
B) respiration only
C) photosynthesis and respiration
D) photosynthesis, respiration, and fermentation
E) none of the above

Answer 35

C photosynthesis and respiration

Question 36

Gene therapy is a possible new way to treat many diseases, including cancer, by turning genes back on. In cancer, a gene for
which type of protein would you most likely want to turn back on?
A) transcription factor protein
B) kinase protein
C) intracellular receptor protein
D) none of the above
E) phosphatase protein

Answer 36

E phosphatase protein

Question 37

47) Where in a plant cell does the Calvin cycle take place?
A) thylakoid membrane
B) outer membrane of the chloroplast
C) interior of the thylakoid (thylakoid space)
D) stroma of the chloroplast
E) none of the above

Answer 37

D stroma of the chloroplast

Question 38

50) The following receptor is activated following the binding of a ligand and subsequent dimerization:
A) G protein-coupled receptor
B) ion channel receptor
C) hormone receptor
D) adenylyl cyclase
E) none of the above

Answer 38

E none of the above