Exam 4

Question 1

Useful energy is obtained by cells when sugars derived from food are broken down by which processes?

A. glycolysis, the Calvin cycle, and oxidative phosphorylation
B. gluconeogenesis, fermentation, and oxidative phosphorylation
C. glycolysis, the citric acid cycle, and oxidative phosphorylation
D. gluconeogenesis, the citric acid cycle, and oxidative phosphorylation
E. glycolysis, the citric acid cycle, and gluconeogenesis

Answer 1

C. glycolysis, the citric acid cycle, and oxidative phosphorylation

Question 2

Although the citric acid cycle itself does not use O2, it requires a functioning electron transport chain (which uses O2) in order to regenerate which molecule for further use in the citric acid cycle?

A. NAD+
B. ADP
C. FADH2
D. ATP
E. NADH

Answer 2

A. NAD+

Question 3

Which two-carbon molecule enters the citric acid cycle?

A. glucose
B. carbon dioxide
C. pyruvate
D. acetyl CoA
E. citrate

Answer 3

D. acetyl CoA

Question 4

How do enzymes maximize the energy harvested from the oxidation of food molecules?

A. They allow a larger of energy to be released from food molecules such as glucose.
B. They allow oxidation reactions to take place without an input of activation energy.
C. They guarantee that each reaction involved in the oxidation of food molecules proceeds in just one direction.
D. They allow what would otherwise be an energetically unfavorable oxidation reaction to occur.
E. They allow the stepwise oxidation of food molecules, which releases energy in small amounts.

Answer 4

E. They allow the stepwise oxidation of food molecules, which releases energy in small amounts.

Question 5

What happens to the energy captured during glycolysis and the citric acid cycle by the activated carriers NADH and FADH2?

A. It is passed to ADP to form ATP.
B. It is used to drive biosynthetic reactions.
C. It is passed to an electron transport chain that uses it to generate a proton gradient across the inner mitochondrial membrane.
D. It is passed to an electron transport chain that uses it to produce oxygen.
E. It is passed to an electron transport chain that uses it to oxidize food molecules.

Answer 5

C. It is passed to an electron transport chain that uses it to generate a proton gradient across the inner mitochondrial membrane.

Question 6

What does pyruvate dehydrogenase complex do?

A. It regenerates NAD+ in the mitochondrial matrix.
B. It converts pyruvate into acetyl CoA in the mitochondrial matrix.
C. It produces pyruvate in the cytosol.
D. It converts pyruvate into acetyl CoA in the cytosol.
E. It completes the oxidation of pyruvate to CO2 in the mitochondrial matrix.

Answer 6

B. It converts pyruvate into acetyl CoA in the mitochondrial matrix.

Question 7

Which of the following statements is NOT true of mitochondria?

A. They contain an outer membrane, an inner membrane, and two internal compartments.
B. In plant cells, they are replaced by chloroplasts.
C. They contain their own DNA and RNA
D. None of the above
E. Inside a cell, they are mobile, constantly changing in shape and position.

Answer 7

B. In plant cells, they are replaced by chloroplasts.

Question 8

What is true of mobile electron carriers?

A. They transfer electrons to oxygen to produce water.
B. They pump protons across a membrane.
C. None of the above.
D. They accept electrons from NADH.
E. They ferry electrons between one respiratory complex and the next.

Answer 8

E. They ferry electrons between one respiratory complex and the next.

Question 9

In photosynthesis, what drives the generation of ATP by ATP synthase?

A. The generation of a charge separation in the photosynthetic reaction center.
B. The phosphorylation of ATP synthase.
C. The transfer of high-energy electrons to ATP synthase.
D. The absorption of light by a photosynthetic reaction center
E. A proton gradient across the thylakoid membrane.

Answer 9

E. A proton gradient across the thylakoid membrane.

Question 10

! How does the photosynthetic machinery produce enough energy to transfer electrons from H2O to NADPH?

A. Two photosystems operating in series couple their electron-energizing steps.
B. The proton gradient produced by electron transport powers the production of NADPH.
C. ATP produced by photosystem II powers the synthesis of NADPH
D. The proton gradient produced by electron transport lowers the redox potential of H2O.
E. Two photosystems operating in series generate enough light energy to produce NADPH.

Answer 10

A. Two photosystems operating in series couple their electron-energizing steps.

Question 11

! During photosynthesis, what happens in the water splitting step?

A. It is catalyzed by an enzyme containing an iron sulfur cluster.
B. It occurs on the stromal side of the thylakoid membrane.
C. It generates essentially all of the O2 in the Earth’s atmosphere.
D. It consumes protons and thereby depletes the proton gradient across the thylakoid membrane.
E. It takes place during stage 2 of photosynthesis.

Answer 11

C. It generates essentially all of the O2 in the Earth’s atmosphere.

Question 12

What provides the fuel to convert CO2 into sugars in chloroplasts?

A. ATP and NADPH generated in the photosynthetic light reactions
B. oxidation of food molecules.
C. Nothing; the reactions do not require energy
D. ATP generated by cell respiration
E. A proton gradient across a membrane

Answer 12

A. ATP and NADPH generated in the photosynthetic light reaction.

Question 13

! What is true of stage 2 of photosynthesis?

A. It takes place in the chloroplast grana.
B. It begins with the production of ATP and NADPH and ends with their consumption.
C. It produces glyceraldehyde 3-phosphate in the stroma.
D. It generates a proton gradient across the thylakoid membrane.
E. It produces all of the O2 we breathe.

Answer 13

C. It produces glyceraldehyde 3-phosphate in the stroma.

Question 14

What is the main function of intermediate filaments?

A. They enable cells to withstand the mechanical stress that occurs when cells are stretched.
B. They provide tracks for guiding intracellular transport.
C. They enable cells to crawl.
D. They segregate chromosomes during cell division.
E. They enable muscle cells to contract.

Answer 14

A. They enable cells to withstand the mechanical stress that occurs when cells are stretched.

Question 15

! What does the cellular motility of sperm depend on?

A. microtubules and kinesin
B. actin and kinesin
C. none of the above
D. actin and myosin
E. microtubules and dynein

Answer 15

E. microtubules and dynein

Question 16

! In a centrosome, which structures serve as nucleation sites for formation of microtubules?

A. alpha- and beta-tubulin dimers
B. gamma-tubulin rings
C. nuclear lamina
D. alpha-beta-tubulin dimers
E. tubulin protofilaments

Answer 16

B. gamma-tubulin rings

Question 17

Dynamic instability is the ability of a microtubule to do which of the following?

A. grow rapidly during mitosis
B. shrink rapidly during mitosis
C. rapidly switch its plus and minus ends
D. none of the above
E. switch back and forth between polymerization and depolymerization

Answer 17

E. switch back and forth between polymerization and depolymerization.

Question 18

! Taxol, a plant alkaloid originally found in yew trees, is an anticancer drug. How does Taxol prevent cell division?

A. Taxol prevents actin filament depolymerization halting mitosis.
B. Taxol prevents microtubule polymerization, halting DNA replication.
C. Taxol prevents actin filament polymerization halting mitosis.
D. Taxol prevents microtubule depolymerization, halting mitosis.
E. Taxol stabilizes intermediate filaments of the nuclear lamina, preventing nucleus breakdown during mitosis.

Answer 18

D. Taxol prevents microtubule depolymerization, halting mitosis.

Question 19

! Inside a muscle fiber, what triggers sacromeres to contract?

A. a sudden rise in Ca2+ inside an organelle lumen
B. a sudden rise in cytosolic Ca2+
C. A sudden rise in cytosolic Na+
D. polarization of the muscle fiber plasma membrane
E. an increased availability of ATP

Answer 19

B. A sudden rise in cytosolic Ca2+

Question 20

! When a muscle is stimulated to contract, what does Ca2+ bind to, and what effect does that have?

A. tropomyosin, which moves the troponin that otherwise blocks the interaction of actin and myosin
B. none of the above
C. actin, allowing it to associate with myosin
D. myosin, allowing it to associate with actin
E. troponin, which moves the tropomyosin that otherwise blocks the interaction of actin and myosin

Answer 20

E. troponin, which moves the tropomyosin that otherwise blocks the interaction of actin and myosin

Question 21

! What does cell crawling depend on?

A. intermediate filaments
B. microtubule assembly
C. actin filament polymerization
D. hydrolysis of ADP by motor proteins
E. the protein called crawlin

Answer 21

C. actin filament polymerization

Question 22

! Signaling via a GPCR ceases when which condition occurs?

A. The alpha subunit dissociates from the beta-gamma complex.
B. The G protein associates with an activated GPCR.
C. The alpha subunit hydrolyzes its bound GTP.
D. The alpha subunit hydrolyzes its bound GTP.
E. The G protein dissociates from the activated GPCR.

Answer 22

C. The alpha subunit hydrolyzes its bound GTP.

Question 23

Which response to GPCR stimulation would be most rapid?

A. change in the activation of a set of target genes.
B. activation of a G protein that regulates the opening of an ion channel.
C. activation of a G protein that activates phospholipase C.
D. activation of a G protein that activates adenylyl cyclase
E. activation of a G protein that inhibits adenylyl cyclase.

Answer 23

B. activation of a G protein that regulates the opening of an ion channel.

Question 24

! When activated phospholipase C cleaves an inositol phospholipid, what happens to the small signaling molecules the enzyme produces?

A. inositol 1,4,5-triphosphate (iP3) remains in the membrane, while diacylglycerol is released into the membrane.
B. Both inositol 1,4,5-triphosphate (iP3) and diacylglycerol are released into the cytosol.
C. Both inositol 1,4,5-triphosphate (iP3) and Ca2+ are released into the cytosol.
D. inositol 1,4,5-triphosphate (iP3) remains in the membrane, while diacylglycerol is released into the cytosol.
E. Both inositol 1,4,5-triphosphate (iP3) and diacylglycerol are retained in the membrane.

Answer 24

A. inositol 1,4,5-triphosphate (iP3) remains in the membrane, while diacylglycerol is released into the membrane.

Question 25

Which of the following would produce the fastest response to G-protein activation?

A. cyclic BTS production
B. production of inositol triphosphate
C. ion channel activation
D. cyclic AMP production
E. cyclic GMP production

Answer 25

C. ion channel activation

Question 26

! What type of cell response would take the longest amount of time (on the scale of minutes to hours) to execute?

A. one that involves the release of secretory vesicles
B. one that involves a change in gene expression
C. one that uses a phosphorylation event to activate an enzyme
D. none of the above
E. one that involves the firing of an action potential along a neuron.

Answer 26

B. one that involves a change in gene expression

Question 27

! How can cyclic AMP, generated by adenylyl cyclase at the plasma membrane, activate the transcription of target genes?

A. The cyclic AMP opens channels in the nuclear membrane, allowing transcription regulators to enter and activate genes.
B. The cyclic AMP diffuses into the nucleus and binds to a cyclic AMP response element on target genes.
C. The cyclic AMP binds to and activates cytosolic nuclear receptors, which enter the nucleus to transcribe target genes.
D. The cyclic AMP activates PKA, which can enter the nucleus and phosphorylate specific transcription regulators.
E. The cyclic AMP binds to and activates specific transcription regulators.

Answer 27

D. The cyclic AMP activates PKA, which can enter the nucleus and phosphorylate specific transcription regulators.

Question 28

! Cellular respiration can best be described as

A. taking electrons from food and giving them to phosphate to make ATP
B. using energy released from breaking high-energy covalent bonds in organic molecules to force ATP formation from ADP and phosphate.
C. taking electrons from food and giving them to oxygen to make water, using the energy released to drive ATP formation.
D. none of the above
E. converting high-energy organic molecules to lower-energy organic molecules and using the energy released to drive ATP formation.

Answer 28

C. taking electrons from food and giving them to oxygen to make water, using the energy released to drive ATP formation.

Question 29

What is the terminal electron acceptor of the electron-transport chain in cells undergoing aerobic respiration?

A. CO
B. glucose
C. CO2
D. O2
E. water

Answer 29

D. O2

Question 30

! What is unusual about the way that H+ ions are transported across the inner mitochondrial membrane as compared to the movement of other ions like Na+ and Cl- ions?

A. Na+ and Cl- ions can hop through a channel by exchanging themselves with other similar ions found along the pathway, but H+ ions must traverse the full distance.
B. Na+ and Cl- ions must traverse the full distance, but H+ ions materialize on the other side of the membrane.
C. Na+ and Cl- ions must traverse the distance, but H+ ions can hop through a channel by exchanging themselves with other protons found along the pathway.
D. Na+ and Cl- ions must traverse the full distance, but H+ ions must change into neutrons first.
E. Na+ and Cl- ions must traverse the full distance, but H+ ions must only go halfway.

Answer 30

C. Na+ and Cl- ions must traverse the distance, but H+ ions can hop through a channel by exchanging themselves with other protons found along the pathway.

Question 31

In the electrochemical gradient established in mitochondria (do not fooled by % numbers those are arbitrary) :

A. 80% of the free energy generated by the proton-motive force is derived from the voltage gradient and 20% is derived from the chemical gradient
B. 20% of the free energy generated by the proton-motive force is derived from the voltage gradient and 80% is derived from the chemical gradient
C. This was not covered during lecture !
D. 50% of the free energy generated by the proton-motive force is derived from the voltage gradient and 41% is derived from the chemical gradient.
E. I have no idea…

Answer 31

A. 80% of the free energy generated by the proton-motive force is derived from the voltage gradient and 20% is derived from the chemical gradient

Question 32

Which of the following statements best describes what happens to a molecule of NAD+ when it gains a hydrogen atom?

A. NAD+ becomes oxidized.
B. NAD+ becomes reduced.
C. NAD+ becomes dehydrogenated.
D. none of the above
E. NAD+ becomes ionized.

Answer 32

B. NAD+ becomes reduced.

Question 33

Which of the following statements best describes the relationship between photosynthesis and cellular respiration?

A. None of the above
B. Photosynthesis occurs only in plants; cellular respiration occurs only in animals.
C. Cellular respiration runs the biochemical pathways of photosynthesis in reverse.
D. Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.
E. Photosynthesis is catabolic; cellular respiration is anabolic.

Answer 33

D. Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.

Question 34

On a diet consisting of nothing but protein, which of the following is the most likely outcome?

A. tiredness because amino acids cannot be used to generate energy
B. muscle gain because the amino acids will go directly into building muscle
C. none of the above
D. excretion of more nitrogenous (ammonia-derived) wastes than with a more balanced diet
E. loss of weight because amino acids cannot be used for the synthesis of fat

Answer 34

D. excretion of more nitrogenous (ammonia-derived) wastes than with a more balanced diet

Question 35

Which of the following describes functions performed by the cytoskeleton?

A. positions various organelles within the cell interior
B. all of these choices are correct
C. provides structural support that determines cell shape and resists deforming forces
D. provides a network of tracks over which materials like mRNA and organelles move within cells
E. serves as a force-generating apparatus that moves cells from one place to another

Answer 35

B. all of these choices are correct

Question 36

Motor proteins are able to generate force by

A. making bonds AND adding amino acids to the end of the molecular motor
B. polymerization of protofilaments
C. depolymerization of protofilaments
D. adding amino acids to the end of the molecular motor
E. undergoing a series of conformation changes

Answer 36

E. undergoing a series of conformation changes

Question 37

Which of the following statements about the cytoskeleton is FALSE?

A. The cytoskeleton controls the location of organelles in eukaryotic cells.
B. none of the above
C. Covalent bonds between protein monomers hold together cytoskeletal filaments.
D. The cytoskeleton of a cell can change in response to the environment.
E. The cytoskeleton is made up of three types of protein filaments.

Answer 37

C. Covalent bonds between protein monomers hold together cytoskeletal filaments.

Question 38

Which of the following statements about the function of the centrosome is FALSE?

A. Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.
B. Centrosomes contain hundreds of copies of the ?-tubulin ring complex important for microtubule nucleation.
C. all of the above
D. Centrosomes typically contain a pair of centrioles, which is made up of a cylindrical array of short microtubules.
E. Centrosomes are the major microtubule-organizing center in animal cells.

Answer 38

A. Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.

Question 39

! Which of the following statements about organeller movement in the cell is FALSE?

A. Organelles undergo saltatory movement in the cell.
B. all of the above
C. Motor proteins involved in organellar movement use ATP hydrolysis for energy.
D. Only the microtubule cytoskeleton is involved in organellar movement.
E. Organelles are attached to the tail domain of motor proteins.

Answer 39

D. Only the microtubule cytoskeleton is involved in organellar movement

Question 40

! For both actin and microtubule polymerization, nucleotide hydrolysis is important for

A. all of the above
B. increasing the rate at which subunits are added to the filaments
C. decreasing the binding strength between subunits on filaments
D. stabilizing the filaments once they are formed
E. promoting nucleation of filaments.

Answer 40

C. decreasing the binding strength between subunits on filaments

Question 41

! Consider the mechanism by which actin and tubulin polymerize. Which of the items below does not describe something similar about the polymerization mechanisms of actin and microtubules?

A. Free subunits (actin and tubulin) carry nucleoside triphosphates.
B. none of the above
C. Depolymerization initiates at the plus ends of filaments.
D. Although both filaments can grow from both ends, the growth rate is faster at the plus ends.
E. Nucleotide hydrolysis promotes depolymerization of filaments.

Answer 41

C. Depolymerization initiates at the plus ends of filaments.

Question 42

What is meant by signal transduction?

A. only when the messenger molecules reach their target cells via passage through bloodstream
B. Overall process of translating information from an intracellular messenger into extracellular changes.
C. Overall process of translating information from an extracellular messenger into cellular changes
D. None of these is the correct answer.
E. Overall process of sending chemical messages.

Answer 42

C. Overall process of translating information from an extracellular messenger into cellular changes.

Question 43

In endocrine signaling, ___

A. the cell producing the messenger expresses receptors on its surface that can respond to that messenger.
B. none of the above.
C. the messenger molecules travel only short distances through the extracellular space to cells that are in close proximity to the cell that is generating the message.
D. the messenger molecules reach their target cells via passage through bloodstream
E. the messenger molecules are usually limited in their ability to travel around the body because they are inherently unstable or they are degraded by enzyme or they bind to extracellular matrix.

Answer 43

D. the messenger molecules reach their target cells via passage through bloodstream.

Question 44

! Which of the following is (are) characteristic of the pathways activated by second messengers?

A. Alterations in signaling protein conformations are often accomplished by protein kinases and protein phosphatases that, respectively, add or remove phosphate groups from other proteins.
B. All of these answers are correct.
C. Each signaling pathway consists of a series of distinct proteins that operate in sequence.
D. None of these answers are correct.
E. Some pathway phosphatases and protein kinases have numerous proteins as their substrates; others act on only a single protein substrate or a single amino acid of a protein substrate.

Answer 44

B. All of these answers are correct.

Question 45

! Which of the following statements is TRUE?

A. None of the above
B. Paracrine signaling involves the secretion of signals into the bloodstream for distribution throughout the organism.
C. Because endocrine signals are broadcast throughout the body, all cells will respond to the hormonal signal.
D. The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling.
E. The axons of neurons typically signal target cells using membrane-bound signaling molecules that act on receptors in the target cells.

Answer 45

D. The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling.

Question 46

Which of the following statements is TRUE?

A. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
B. None of the above.
C. Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type.
D. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol.
E. A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response.

Answer 46

A. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.

Question 47

! Which of the following statements is FALSE?

A. Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.
B. Some signal molecules can bind directly to intracellular proteins that bind DNA & regulate gene transcription.
C. None of the above.
D. Some signal molecules are transmembrane proteins.
E. Nucleotides and amino acids can act as extracellular signal molecules.

Answer 47

A. Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.

Question 48

Where are steroid receptors generally located and where do they bind the steroid hormone once it enters the cell?

A. The receptors are located in the cytoplasm but they bind their ligands in the lysosomes.
B. They are located and bind the steroids in the middle of the cell membrane.
C. They are located and bind the steroids in the cytoplasm.
D. They are located and bind the steroids on the extracellular membrane surface.
E. None of the above.

Answer 48

C. They are located and bind the steroids in the cytoplasm.

Question 49

Actin filaments use ____ hydrolysis and the motor protein(s) ____ while microtubules use ___ hydrolysis and the motor protein(s) ___.

A. ATP; kinesins; ATP; kinesins and dyneins
B. ATP; myosin; ATP; kinesins & dyneins
C. ATP; myosin; GTP; kinesins & dyneins
D. ATP; kinesins & dyneins; GTP; myosins
E. GTP; myosin; ATP; kinesins & dyneins

Answer 49

C. ATP; myosin; GTP; kinesins & dyneins

Question 50

! Cytochrome C, or Cyt C for short, is an intermediate electron carrier involved in the electron transport chain. If there were a mutation that impedes the ability for cyt c to work properly, where would this cause a direct issue and what would be the overall issue of it?

A. Due to cyt c being an intermediate in the glycolysis cycle, substrate level phosphorylation would decrease. However, a moderate amount of energy would still be made in oxidative phosphorylation.
B. It would not matter too much, as the cell would produce a lot more ubiquinone to make up for this mutation. Therefore, the level of ATP production would be relatively normal.
C. The electrons could not be transported from complex 1 to complex 3, and thus would overall decrease/prevent the production of GTP via oxidative phosphorylation.
D. none of the above
E. The electrons could not be transported from complex 3 to complex 4, and thus would overall decrease/prevent the production of ATP via oxidative phosphorylation.

Answer 50

E. The electrons could not be transported from complex 3 to complex 4, and thus would overall decrease/prevent the production of ATP via oxidative phosphorylation.

Question 51

(EC) What is the full name of RuBisco that catalyzes a reaction in the citric acid cycle?

A. Ribulose-1,5-biphosphate carboxylase
B. Ribose-1,5-biphosphate carboxylase-oxygenase
C. Ribose-1,5-biphosphate cooxygenase
D. RNAse-1,5-biphosphate carboxylase-oxyphophatase
E. Ribulose-1,5-biphosphate carboxylase-oxygenase

Answer 51

E. Ribulose-1,5-biphosphate carboxylase-oxygenase

Question 52

! (EC) What disease is linked to MAPs?

A. Alzheimer’s disease – according to Sarah
B. Lou Gehrig’s disease – according to Evan
C. Parkinson’s disease – according to Andrew
D. Huntington’s disease – according to Autumn
E. Epidermolysis bullosa simplex (EBS) – according to Kaci

Answer 52

A. Alzheimer’s disease – according to Sarah

Question 53

(EC) What is the name of Dae-Sung’s dog?

Answer 53

Dusty