Multiple Choice Qs Redo

Question 1

Which elements make up approx 96% of living matter

Answer 1

C H N O

Question 2

Van der walls interactions result when?

Answer 2

Electrons are not symmetrically distributed in a molecule

Question 3

What bonding or interaction is most likely to occur among broad array of molecules of various types (polar, nonpolar, etc)

Answer 3

Van der waals

Question 4

Ionic bonds form as a result of…

Answer 4

Attraction between ions that have opposite charges

Question 5

A hydrogen bond is…

Answer 5

A weak chemical bond

Question 6

When do h bonds occur

Answer 6

When partial opposite charges on molecules come close enough to attract each other

Question 7

Many mammals control their body temp by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temp?

Answer 7

The absorption of heat by the breaking of hydrogen bonds

Question 8

Why does evaporation of water from a surface cause cooling of the surface ?

Answer 8

The water molecules with the most heat energy evaporate the most readily

Question 9

Which of the following occurs because molecules of water are farther apart in ice than in liquid water

Answer 9

Ice floats

Question 10

Sweating has a cooling effect because of water’s high

Answer 10

Heat of vaporization

Question 11

In animal metabolism, most of the monomers released by digestion of food macromolecules are metabolized to provide energy . Only a small portion of these monomers are used for synthesis of new macromolecules. The net result is that….

Answer 11

Water is consumed by animal metabolism

Question 12

13) Why are human sex hormones considered to be lipids?
a) They are essential components of cell membranes.
b) They are not soluble in water.
c) They are made of fatty acids.
d) They are hydrophilic compounds.
e) They contribute to atherosclerosis.

Answer 12

b) They are not soluble in water.

Question 13

14) Which modifications of fatty acids will best keep triglycerides solid at warmer temperatures?
a) creating cis double bonds to the fatty acids
b) adding hydrogens to the fatty acids
c) creating trans double bonds to the fatty acids
d) adding hydrogens and trans double bonds to the fatty acids
e) adding cis double bonds and trans double bonds to the fatty acids

Answer 13

d) adding hydrogens and trans double bonds to the fatty acids

Question 14

18) Which of the following statements is true for triglycerols?
a) They are insoluble in water.
b) They are made from glycerol, fatty acids, and phosphate.
c) They contain less energy than proteins and carbohydrates.
d) They are made by dehydration reactions.
e) More than one answer is true.

Answer 14

e) More than one answer is true.

Question 15

20) Which of the following statements concerning saturated fats is not true?
a) They are more common in animals than in plants.
b) They have multiple double bonds in the carbon chains of their fatty acids.
c) They generally solidify at room temperature.
d) They contain more hydrogen than unsaturated fats having the same number of carbon atoms.
e) They are one of several factors that contribute to atherosclerosis.

Answer 15

b)

Question 16

23) What is a difference between saturated triacylglycerols and unsaturated triacylglycerols?
a) Saturated triacylglycerols have more double bonds than unsaturated triacylglycerols do.
b) Saturated triacylglycerols are fats; unsaturated triacylglycerols are steroids.
c) Saturated triacylglycerols are liquid at room temperature.
d) For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms
than unsaturated triacylglycerols do.
e) Saturated triacylglycerols are saturated with hydrogen atoms.

Answer 16

d)

Question 17

30) Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by
__________.
a) ionic bonds
b) ester linkages
c) glycosidic linkages
d) peptide bonds
e) phosphodiester linkages

Answer 17

b)

Question 18

) Explain what happens if even one amino acid is substituted for another in a polypeptide chain.
Provide two specific examples.

Answer 18

Amino acid substitution alters a protein’s primary structure. Since
different amino acids have differently shaped & sized functional groups, the new functional group will
highly likely affect the protein’s hydrogen bonding, which changes the formation of secondary structures
like helices and sheets. If the secondary structure changes, the tertiary structure will also change
(again because of changes in hydrogen bonds as well as changes in hydrophobic interactions, ionic bonds
& disulfide bonds). If the polypeptide is part of an oligomeric protein, the quaternary structure will also
change its conformation. Once the shape of a protein has been altered, the function will also be altered.
Specific examples include sickle cell anemia, misfolding of proteins caused by prions (like mad cow’s
disease), misfolding of proteins in Alzheimer’s Disease.

Question 19

3) What is the function of actin and myosin?

Answer 19

Actin and myosin are contractile proteins. They are
abundant in muscles, facilitating contraction and elongation of these cells. Myosin proteins form
filaments that have “feet-like” structures that “walk” along the actin proteins (also filamentous) to
shorten or lengthen a muscle cell. They also facilitate the movement of cilia and flagella.

Question 20

36) Upon chemical analysis, a particular polypeptide was found to contain n amino acids. How many
peptide bonds are present in this protein?
a) n + 1
b) n
c) n - 1
d) n – 2
e) none of the answers are correct

Answer 20

c)

Question 21

39) Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins?
a) hydrophobic interactions
b) disulfide bonds
c) ionic bonds
d) hydrogen bonds
e) peptide bonds

Answer 21

d)

Question 22

40) The R group or side chain of the amino acid serine is –CH₂–OH. The R group or side chain of the
amino acid leucine is –CH₂–CH–(CH₃)₂. Where would you expect to find these amino acids in a globular
protein in aqueous solution?
a) Serine would be in the interior, and leucine would be on the exterior of the globular protein.
b) Leucine would be in the interior, and serine would be on the exterior of the globular protein.
c) Both serine and leucine would be in the interior of the globular protein.
d) Both serine and leucine would be on the exterior of the globular protein.
e) Both serine and leucine would be in the interior and on the exterior of the globular protein.

Answer 22

b)

Question 23

41) What aspects of protein structure are stabilized or assisted by hydrogen bonds?
a) primary structure
b) secondary structure
c) tertiary structure
d) quaternary structure
e) secondary, tertiary, and quaternary structures

Answer 23

e)

Question 24

48) Which of the following lists ranks these molecules in the correct order by size from largest to
smallest?
a) water, protein, sucrose, glucose
b) water, glucose, sucrose, protein
c) glucose, water, sucrose, protein
d) protein, water, glucose, sucrose
e) water, sucrose, glucose, protein

Answer 24

b)

Question 25

49) Which of the following represents a specific description of a polypeptide?
a) organic molecules linked by dehydration reactions
b) carbohydrates with a hydrogen bond holding them together
c) organic monomers covalently bonded
d) amino acids linked by hydrolysis
e) None of the listed responses is correct.

Answer 25

c)

Question 26

56) What do Alzheimer’s and mad cow disease have in common?
a) Both are caused by the buildup of misfolded proteins in cells.
b) Both are associated with plaque buildup in arteries (atherosclerosis).
c) Both are associated with the buildup of misfolded proteins in cells.
d) Both are associated with the buildup of lipids in brain cells due to faulty lysosome activity.
e) Both cause the misfolding of nucleic acids.

Answer 26

c)

Question 27

4) Examples of an exergonic (catabolic) reaction include the formation of
a) maltose from glucose.
b) fatty acids and glycerol from lipids.
c) ATP and water from ADP and inorganic phosphate.
d) glucose and oxygen from carbon dioxide and water.

Answer 27

b)

Question 28

9) Which of the following statements is representative of the second law of thermodynamics?
a) Conversion of energy from one form to another is always accompanied by some gain of free
energy.
b) Heat represents a form of energy that can be used by most organisms to do work.
c) Without an input of energy, organisms would tend toward decreasing entropy.
d) Cells require a constant input of energy to maintain their high level of organization.
e) Every energy transformation by a cell decreases the entropy of the universe.

Answer 28

d)

Question 29

13) Why is ATP an important molecule in metabolism?
a) Its hydrolysis provides an input of free energy for exergonic reactions.
b) It provides energy coupling between exergonic and endergonic reactions.
c) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases
free energy.
d) Its terminal phosphate bond has higher energy than the other two.
e) It is one of the four building blocks for DNA synthesis.

Answer 29

b)

Question 30

16) Which of the following statements is true about enzyme-catalyzed reactions?
a) The reaction is faster than the same reaction in the absence of the enzyme.
b) The free energy change of the reaction is opposite from the reaction that occurs in the absence
of the enzyme.
c) The reaction always goes in the direction toward chemical equilibrium.
d) Enzyme-catalyzed reactions require energy to activate the enzyme.
e) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.

Answer 30

a)

Question 31

22) Zinc, an essential trace element for most organisms, is present in the active site of the enzyme
carboxypeptidase. The zinc most likely functions as a(n)
a) competitive inhibitor of the enzyme.
b) noncompetitive inhibitor of the enzyme.
c) allosteric activator of the enzyme.
d) cofactor necessary for enzyme activity.
e) coenzyme derived from a vitamin..

Answer 31

d)

Question 32

23) Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse
transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly
acquires mutations with amino acid changes that make them resistant to these competitive inhibitors.
Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drugresistant viruses?
a) in or near the active site
b) at an allosteric site
c) at a cofactor binding site
d) in regions of the protein that determine packaging into the virus capsid
e) such mutations could occur anywhere with equal probability

Answer 32

a)

Question 33

26) The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the
pathway is most precisely described as
a) metabolic inhibition.
b) feedback inhibition.
c) allosteric inhibition.
d) noncooperative inhibition.
e) reversible inhibition.

Answer 33

b)

Question 34

27) Which of the following statements describes enzyme cooperativity?
a) A multienzyme complex contains all the enzymes of a metabolic pathway.
b) A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway.
c) A substrate molecule bound to an active site of one subunit promotes substrate binding to the
active site of other subunits.
d) Several substrate molecules can be catalyzed by the same enzyme.
e) A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.

Answer 34

c)

Question 35

29) Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites,
whereas protein phosphatases catalyze removal of phosphate(s) from phosphorylated proteins.
Phosphorylation and dephosphorylation can function as an on-off switch for a protein’s activity, most
likely through
a) the change in a protein’s charge leading to a conformational change.
b) the change in a protein’s charge leading to cleavage.
c) a change in the optimal pH at which a reaction will occur.
d) a change in the optimal temperature at which a reaction will occur.
e) the excision of one or more peptides.

Answer 35

a)

Question 36

37) Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is
inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate
dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic
acid. Based on this information, which of the following is correct?
a) Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
b) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
c) Succinate is the substrate, and fumarate is the product.
d) Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
e) Malonic acid is the product, and fumarate is a competitive inhibitor.

Answer 36

c)

Question 37

7) Which of the following statements about the role of phospholipids in the structure and function of
biological membranes is correct?
a) They are triacylglycerols, which are commonly available in foods.
b) Phospholipids form a selectively permeable structure.
c) Phospholipids form a structure in which the hydrophobic portion faces outward.
d) Phospholipids are completely unable to interact with water.
e) Phospholipids form a single sheet in water.

Answer 37

b)

Question 38

9) Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma
membrane would cholesterol most likely be found?
a) on the inside (cytoplasmic) surface
b) in the interior and on the inside surface, but not on the outside surface
c) in the interior of the membrane
d) on the outside (external) surface of the membrane
e) on either surface of the membrane, but not in the interior of the membrane

Answer 38

c)

Question 39

11) Which of the following functions of membrane proteins is important in tissue formation during
embryonic development in animals?
a) Membrane proteins possess enzymatic activity.
b) Membrane proteins with short sugar chains form identification tags that are recognized by other
cells.
c) Membrane proteins attach the membrane to the cytoskeleton.
d) Membrane proteins form channels, which move substances across the membrane.
e) All of the listed responses are correct.

Answer 39

b)

Question 40

13) Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the
membrane would carbohydrates most likely be found?
a) on the outside (external) surface of the membrane
b) Carbohydrates are rarely associated with plasma membranes.
c) in the interior of the membrane
d) on the inside (cytoplasmic) surface of the membrane
e) on both hydrophilic surfaces of the membrane but not in the hydrophobic interior

Answer 40

a)

Question 41

17) Freshwater protozoans react to a/an _______ environment by removing water
through __________.
a) hypertonic, turgor pressure
b) hypotonic, turgor pressure
c) isotonic, a contractile vacuole
d) hypertonic, a contractile vacuole
e) hypotonic, a contractile vacuole

Answer 41

e)

Question 42

18) Which of the following statements about passive transport is correct?
a) In passive transport, solute movement stops when the solute concentration is the same on both
sides of the membrane.
b) Passive transport permits the solute to move in either direction, but the net movement of solute
molecules occurs down the concentration gradient of the molecule.
c) Passive transport does not occur in the human body.
d) Passive transport operates independently of diffusion.
e) Passive transport operates independently of the concentrations of the moving solute.

Answer 42

b)

Question 43

19) Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than
cell B. and cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more
rapidly into cell __________ because __________.
a) A … the concentration gradient there is shallower
b) B … the oxygen molecules inside cell B have a higher kinetic energy
c) B … the gradient of oxygen is oriented in the opposite direction compared to cell A
d) B … the diffusion gradient in cell B is steeper
e) A … its membrane transport proteins will not be saturated

Answer 43

d)

Question 44

20) Which of the following statements about diffusion is true?
a) It involves only the movement of water molecules.
b) It is a passive process.
c) It occurs when molecules move from a region of lower concentration to a region of higher
concentration.
d) It always requires integral proteins of the cell membrane.
e) It requires expenditure of energy by the cell.

Answer 44

b)

Question 45

28) The concentration of solutes in a red blood cell is about 2%, but red blood cells contain almost no
sucrose or urea. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would
cause red blood cells to shrink the most when immersed in which of the following solutions?
a) a hypertonic sucrose solution
b) a hypotonic urea solution
c) a hypotonic sucrose solution
d) a hypertonic urea solution
e) pure water

Answer 45

a)

Question 46

30) Active transport requires an input of energy and can also generate voltages across membranes.
Based on this information, which of the following statements is true?
a) Active transport can use ATP as its energy source and ensures that there is no voltage across the
cell membrane.
b) The source of energy for active transport of a solute up its gradient can be ATP or a
concentration gradient of a second solute. This second gradient of solutes maintains no net
difference in voltage across the membrane.
c) The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell
membrane.
d) Active transport moves solutes down their concentration gradients and always uses ATP as the
source of energy to do this.
e) Active transport uses channel proteins aand ensures that the interior of the cell is always positive
compared to the exterior of the cell.

Answer 46

c)

Question 47

31) Glucose can be moved into cells via an active transport mechanism when the concentration of
glucose inside the cell is higher than the concentration of glucose outside of the cell. This active
transport mechanism moves glucose and sodium into the cell at the same time. The glucose moves up
its gradient and the sodium moves down its gradient. Which of the following statements about this
mechanism is accurate?
a) Sodium and glucose move together into the cell via facilitated diffusion.
b) To pump glucose up its concentration gradient, sodium moves down its concentration gradient.
c) The distribution of sodium ions across the membrane forms an electrochemical gradient that
drives this mechanism.
d) Sodium and glucose move together into the cell via facilitated diffusion, and to pump glucose up
its concentration gradient, sodium moves down its concentration gradient.
e) Two of the answers are correct.

Answer 47

e)

Question 48

33) A cell has a membrane potential of –100 mV (more negative inside than outside) and has 1,000
times more calcium ions outside the cell than inside. Which of the following best describes a mechanism
by which Ca2+ enters the cell?
a) movement of Ca2+ into the cell through a carrier protein down its electrical gradient
b) movement of Ca2+ into the cell through an ion channel down its concentration gradient
c) cotransport of Ca2+ into the cell with Cl–
d) passive diffusion of Ca2+ into the cell down its electrochemical gradient
e) facilitated diffusion of Ca2+ into the cell down its electrochemical gradient

Answer 48

e)

Question 49

37) Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
a) receptor-mediated endocytosis
b) facilitated diffusion
c) channel proteins
d) osmosis
e) passive transport

Answer 49

a)

Question 50

39) A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules,
from its mother’s milk. These molecules probably enter the cells lining the baby’s digestive tract via
which process?
a) passive transport
b) endocytosis
c) osmosis
d) exocytosis
e) active transport

Answer 50

b)

Question 51

40) Which of the following pairs correctly matches a membrane transport process to its primary
function?
a) phagocytosis: secretion of large particles from the cell by fusion of vesicles with the plasma
membrane
b) pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the
plasma membrane
c) osmosis: passive diffusion of water and small solutes across a membrane
d) exocytosis: the movement of water and solutes out of the cell by passage through the plasma
membrane

Answer 51

b)

Question 52

21) Signal transduction and glycogen metabolism by glucagon requires
a) insulin to bind simultaneously in the same cell
b) paracrine signaling
c) a transduction pathway of dehydrogenases
d) the signal molecule does not interact directly with the cytosolic enzyme, but requires an intact
plasma membrane before the enzyme could be activated
e) the signal molecule combines directly with a cytosolic enzyme to form an active quaternary
structure

Answer 52

d)

Question 53

24) Steroid hormones can enter a cell by simple diffusion. Therefore steroids __________.
a) are not an example of signaling molecules
b) act by phosphorylating DNA
c) do not bind to receptors
d) directly bind to DNA
e) do not initiate cell signaling by interacting with a receptor in the plasma membrane

Answer 53

e)

Question 54

26) Testosterone does NOT affect all cells of the body because __________.
a) testosterone cannot cross the plasma membrane
b) it is a local regulator
c) not all cells in the body have membrane receptors for testosterone
d) it affects only cells that have ion-channel receptors
e) not all cells have cytoplasmic receptors for testosterone

Answer 54

e)

Question 55

28) Which of the following is activated when the binding of single molecules causes it to form a dimer?
a) G-protein-coupled receptors
b) ion-channel receptors
c) receptor tyrosine kinases
d) protein phosphatase receptors
e) adenylyl cyclase receptors

Answer 55

c)

Question 56

29) The binding of a signal molecule to a ligand-gated ion channel __________.
a) affects the membrane potential
b) promotes the binding of a steroid hormone to its receptor in the cytoplasm
c) results in the formation of ion-channel dimers
d) causes the ion channel to phosphorylate an amino acid on a target molecule
e) alters the expression of genes, especially in neurons

Answer 56

a)

Question 57

30) A G protein is active when __________.
a) Ca2+ binds to a G-protein-coupled receptor
b) GTP is bound to it
c) it is bound by its ligand and transported to the nucleus
d) it is phosphorylated by a protein kinase
e) GDP replaces GTP

Answer 57

b)

Question 58

31) If a modified form of GTP that CANNOT be enzymatically converted to GDP were added to a culture
of cells, the likely result would be __________.
a) receptor tyrosine kinases would be stimulated by the additional phosphate groups present in
the modified GTP
b) that the activated G proteins would remain locked in the “on” position, transmitting signal even
in the absence of a signaling molecule
c) the inactivation of G-protein-coupled signaling pathways
d) the inactivation of ligand-gated ion channels
e) the inhibition of pathways stimulated by tyrosine-kinase receptors

Answer 58

b)

Question 59

32) What event would activate a G protein?
a) phosphorylation of GTP to GDP
b) hydrolysis of GTP to GDP
c) replacement of GDP with GTP
d) hydrolysis of GDP to GTP
e) phosphorylation of GDP to GTP

Answer 59

c)

Question 60

33) Ras, a small G protein located at the plasma membrane, is often mutated in different types of
cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which of
the following changes to Ras could explain uncontrolled division in a cancer cell that has mutated Ras
present?
a) a mutation that leads to Ras being sent to the endomembrane system
b) a mutation in which Ras cannot bind to its GPCR
c) a mutation that means Ras cannot hydrolyze GTP to GDP
d) a mutation that means GDP is constantly bound to Ras
e) a mutation that means Ras cannot bind to GTP

Answer 60

c)

Question 61

34) The cellular response of a signal pathway that terminates at a transcription factor would be
__________.
a) the activation of an inactive enzyme
b) the synthesis of mRNA
c) the activation of a metabolic pathway
d) alteration of the cytoskeleton
e) a change in the chemical composition of the cytosolic environment

Answer 61

b)

Question 62

35) ATPgammaS is a form of ATP that CANNOT be hydrolyzed by enzymes. If this compound were
introduced to cells so that it replaced the normal ATP present in the cell, which of the following would
you predict?
a) an increase in anabolic cellular reactions
b) an increase in the numbers of phosphorylated proteins in the cell
c) an increase in cell division
d) a decrease in phosphorylated proteins in the cell
e) Two of the listed responses would be expected.

Answer 62

d)

Question 63

37) The source of phosphate for a phosphorylation cascade is __________.
a) ADP
b) protein phosphatase
c) protein kinase
d) cAMP
e) ATP

Answer 63

e)

Question 64

38) Second messengers tend to be water-soluble and small. This accounts for their ability to
__________.
a) pass quickly from cell to cell
b) rapidly move throughout the cell by diffusion
c) move from substrate to substrate during a phosphorylation cascade
d) cross the nuclear membrane and interact with DNA
e) rapidly cross the plasma membrane

Answer 64

b)

Question 65

39) The molecule cAMP usually directly activates __________.
a) receptor tyrosine kinases
b) protein kinase A
c) phosphodiesterase
d) G proteins
e) adenylyl cyclase

Answer 65

b)

Question 66

41) Which of the following statements about calcium ions in a typical cell is true?
a) In a typical cell, calcium ions are not very widely used as second messengers.
b) In a typical cell, calcium ions are far more abundant in the cytoplasm than in the blood and
other extracellular fluid.
c) In a typical cell, calcium ions are rapidly transported into the endoplasmic reticulum in response
to G-protein-mediated signals.
d) In a typical cell, calcium ions are often concentrated within the endoplasmic reticulum.
e) All of the listed responses are correct.

Answer 66

d)

Question 67

45) A mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to
__________.
a) an increase in the amount of cAMP present in the cell
b) increased binding of adenylyl cyclase to the G protein that activates it
c) reduced binding of adenylyl cyclase to protein kinase A
d) lower activity of protein kinase A
e) higher activity of protein kinase A

Answer 67

d)

Question 68

47) Which of the following statements about apoptosis is true?
a) Apoptosis is triggered only by signals from outside the cell.
b) Apoptosis typically involves only a single signaling pathway.
c) Apoptosis is essential for normal development of the nervous system.
d) Apoptosis occurs during embryonic development of a nematode.
e) All of the listed responses are correct.

Answer 68

c)

Question 69

) Why is it beneficial for cells to use ATP rather than energy directly from the bonds of carbohydrates?
What are the greatest drawbacks to harnessing energy directly from the bonds of several different
compounds?

Answer 69

Cells would be destroyed by the energy released (as heat) directly from these bonds.

Question 70

How does hexokinase contribute to the facilitated diffusion of glucose?

Answer 70

Phosphorylation of glucose traps it within the cell because the molecule becomes charged. This
maintains the glucose concentration gradient.

Question 71

What accounts for the different number of ATP molecules that are formed through cellular
respiration?

Answer 71

NADH shuttling from the cytoplasm via glycolysis may transfer its electrons to another NAD+
in the mitochondria or FAD+
in the mitochondria. These two electron carriers do not contribute to the
same number of ATPs produced in oxidative phosphorylation. (Also, different sources don’t always
calculate the contribution of these electron carriers to ATP molecules the same way. Ie. one NADH =
three ATP for some, or 2.5 ATP for others.)

Question 72

How does citrate from the citric acid cycle affect glycolysis?

Answer 72

Citrate is an allosteric inhibitor of PFK in
the glycolysis pathway. It’s levels help regulate the level of ATP present in the cell. If citrate is above
homeostatic levels, it will bind to and inhibit PFK activity (step 3 in glycolysis). This will reduce cellular
respiration until citrate levels return to homeostasis

Question 73

1) In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is
reduced.
a) carbon dioxide … water
b) glucose … ATP
c) glucose … oxygen
d) oxygen … ATP
e) ATP … oxygen

Answer 73

C)

Question 74

3) Which of the following is a correct description of the events of cellular respiration in proper
sequence?
a) oxidation of pyruvate; citric acid cycle; oxidation of glucose to pyruvate; oxidative
phosphorylation
b) oxidation of glucose to pyruvate; reduction of pyruvate; citric acid cycle; oxidative
phosphorylation
c) glycolysis; reduction of pyruvate; citric acid cycle; oxidative phosphorylation
d) oxidation of glucose to pyruvate; oxidation of pyruvate; citric acid cycle; oxidative
phosphorylation
e) glycolysis; oxidative phosphorylation; citric acid cycle; oxidation of pyruvate

Answer 74

d)

Question 75

6) During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is the reducing agent?
a) water
b) carbon dioxide
c) glucose
d) oxygen
e) both glucose and carbon dioxide

Answer 75

c)

Question 76

12) There is no production of carbon dioxide in glycolysis. Which of the following is the best explanation
for this fact?
a) The initial steps of glycolysis require an input of energy in the form of ATP (two per glucose).
b) There are no oxidation or reduction reactions in glycolysis to produce CO2.
c) There is very little ATP produced in glycolysis.
d) Glucose contains more carbons than the number of carbons found in the pyruvate products that
are produced by glycolysis.
e) The products of glycolysis contain the same total number of carbon atoms as in the starting
material.

Answer 76

e)

Question 77

13) Which of the following molecules in the process of glycolysis possesses the most chemical energy?
a) glucose
b) pyruvate
c) fructose-1,6-bisphosphate
d) glyceraldehyde-3-phosphate
e) fructose-6-phosphate

Answer 77

c)

Question 78

15) In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen.
The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in
__________.
a) ATP
b) oxygen gas
c) NADH
d) water
e) carbon dioxide

Answer 78

e)

Question 79

16) In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
a) Pyruvate is oxidized and a molecule of carbon dioxide is removed. The electrons removed in this
process are donated to NADH to produce NAD+
.
b) Pyruvate is ionized directly to acetyl-coA.
c) Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a
carbon dioxide from the environment, and its reduction by NADH.
d) Pyruvate is oxidized and a molecule of carbon dioxide is removed. The electrons removed in this
process are used to reduce NAD+
to NADH.
e) Pyruvate is reduced and a molecule of carbon dioxide is removed. The electrons removed in this
process are used to oxidize NAD+
to NADH.

Answer 79

d)

Question 80

20) For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in
the citric acid cycle?
a) one ATP, three NADH, one FADH2
b) four ATP, six NADH, two FADH2
c) three ATP, three NADH, one FADH2
d) about 38 ATP
e) two ATP, six NADH, two FADH2

Answer 80

e)

Question 81

23) Which of the following represents the major (but not the only) energy accomplishment of the citric
acid cycle?
a) utilization of O2
b) formation of NADH and FADH2
c) formation of ATP
d) formation of CO2
e) completion of substrate-level phosphorylation

Answer 81

b)

Question 82

25) Which of the following events accompanies the conversion of pyruvate to acetyl CoA before the
citric acid cycle?
a) regeneration of NAD+
b) removal of coenzyme A
c) release of CO2 and release of coenzyme A
d) release of CO2 and synthesis of NADH
e) formation of CO2 and synthesis of ATP

Answer 82

d)

Question 83

28) When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid
cycle also eventually stop working. Which of the following is the best explanation for this? (Concept 9.4)
a) A high level of NADH is present in the cell.
b) They run out of ADP.
c) The uptake of oxygen stops because electron transport was inhibited.
d) NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.
e) Electrons are no longer available from the electron transport chain to power glycolysis and the
citric acid cycle.

Answer 83

d)

Question 84

29) Most of the electrons removed from glucose by cellular respiration are used for which of the
following processes?
a) reducing NAD+
to NADH in glycolysis and the citric acid cycle
b) producing a proton gradient for ATP synthesis in the mitochondria
c) driving substrate-level phosphorylation in glycolysis
d) The first two choices are correct.
e) The second and third answers are correct.

Answer 84

d)

Question 85

30) Each ATP molecule contains about 1% of the amount of chemical energy available from the
complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one
glucose molecule. What happens to the rest of the energy in glucose?
a) It is converted to heat.
b) It is released as carbon dioxide and water
c) It is converted to starch.
d) It is stored as fat.
e) It is used to make water from hydrogen ions and oxygen.

Answer 85

a)

Question 86

33) During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?
a) at the end of glycolysis to oxidize pyruvate
b) at the end of the citric acid cycle to regenerate citric acid
c) between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2
d) as a source of O2 in every reaction that produces CO2
e) at the end of the electron transport chain to accept electrons and form H2O

Answer 86

e)

Question 87

37) Which of the following is the source of the energy that produces the chemiosmotic gradient in
mitochondria?
a) movement of electrons down the electron transport chain
b) the components of the electron transport chain
c) the production of NADH
d) an ATP-dependent proton pump
e) ATP

Answer 87

a)

Question 88

39) When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent
this, the tumor can recruit new blood vessels. What purpose does the recruitment of blood vessels to
growing tumors serve?
a) It supplies glucose to the rapidly dividing cells of the tumor.
b) It supplies a non-oxygen electron acceptor to cells so that the cells can respire anaerobically.
c) It supplies oxygen so that aerobic cellular respiration can occur instead of fermentation.
d) It supplies a non-oxygen electron acceptor to cells so that the cells can respire anaerobically,
and it supplies oxygen so that aerobic cellular respiration can occur instead of fermentation.
e) Two of the answers are correct.

Answer 88

e)

Question 89

43) In brewing beer, maltose (a disaccharide of glucose) is __________.
a) the substrate for aerobic respiration
b) one of the enzymes for alcoholic fermentation
c) a substitute for pyruvate that cannot be made in yeast
d) a sweetener
e) the substrate for alcoholic fermentation

Answer 89

a)

Question 90

47) A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of
carbohydrate. Which of the following best explains this observation?
a) Fats are less soluble in water than sugars.
b) Fats are better electron donors to oxygen than are sugars.
c) Fats do not form true macromolecules as sugars do.
d) Fats are closely related to lipid molecules, which are the basic building blocks of cellular
membranes.
e) Fats are produced when cells take in more food than they need.

Answer 90

b)

Question 91

48) If significant amounts of materials are removed from the citric acid cycle to produce amino acids for
protein synthesis, which of the following will result?
a) Less ATP will be produced by the cell.
b) Less CO2 will be produced by the cell.
c) The four-carbon compound that combines with acetyl CoA will have to be made by some other
process.
d) The first two answers are correct.
e) The first three answers are correct

Answer 91

e)

Question 92

1) Which order of molecular conversions is correct for the Calvin cycle?
a) RuBP + G3P → 3-PGA → sugar
b) RuBisCo → CO2 → RuBP → G3P
c) RuBP + CO2 → [RuBisCo] 3-PGA → G3P
d) CO2 → 3-PGA → RuBP → G3P

Answer 92

c)

Question 93

4) Dye injected into a plant cell might be able to enter an adjacent cell through __________.
a) a gap junction
b) a cell wall
c) a tight junction
d) a microtubule
e) plasmodesmata

Answer 93

e)

Question 94

10) In photosynthesis, what is the fate of the oxygen atoms present in CO2? They end up __________.
a) in water
b) in sugar molecules
c) as molecular oxygen and in sugar molecules
d) as molecular oxygen
e) in sugar molecules and in water

Answer 94

e)

Question 95

13) The Calvin cycle occurs in the __________.
a) thylakoid lumen
b) thylakoid membrane
c) stroma
d) matrix
e) stomata

Answer 95

c)

Question 96

14) What is the role of NADP+
in photosynthesis?
a) It helps produce ATP from the light reactions.
b) It absorbs light energy.
c) It forms NADPH to be used in the Calvin cycle.
d) It forms part of photosystem II.
e) It is the primary electron acceptor.

Answer 96

c)

Question 97

20) Where do the electrons entering photosystem II come from?
a) the electron transport chain
b) ATP
c) chlorophyll molecules in the antenna complex
d) water
e) light

Answer 97

d)

Question 98

22) Which of the following is cycled in the cyclic variation of the light reactions?
NADPH
a) ribulose bisphosphate
b) electrons
c) ATP
d) protons

Answer 98

b)

Question 99

24) You could distinguish a thylakoid membrane from an inner mitochondrial membrane because the
thylakoid membrane would __________.
a) contain protein but not lipids
b) function in energy transformation
c) be inside a mitochondrion
d) have photosynthetic pigments
e) have all of the listed characteristics

Answer 99

d)

Question 100

28) What is the role of NADP+
in photosynthesis?
a) As a component of photosystem II, it catalyzes the hydrolysis of water.
b) It is reduced and then carries electrons to the Calvin cycle.
c) It assists chlorophyll in capturing light.
d) As part of the electron transport chain, it manufactures ATP.
e) It acts as the primary electron acceptor for the photosystems.

Answer 100

b)

Question 101

29) Of the following, which occurs during the Calvin cycle?
a) ATP and NADPH are synthesized.
b) Light energy is converted to chemical energy.
c) CO2 is reduced.
d) Excited electrons are conveyed from chlorophyll to an electron acceptor.
e) Photons are absorbed.

Answer 101

c)

Question 102

30) Which of the following occurs during the Calvin cycle?
a) ATP is oxidized and NADPH is oxidized.
b) ATP is hydrolyzed and NADPH is oxidized.
c) Light energy is converted to chemical energy.
d) Linear electron flow produces the materials required for the fixation of carbon from carbon
dioxide.
e) ATP is reduced and NADPH is oxidized.

Answer 102

b)

Question 103

32) In the Calvin cycle, CO2 is combined with __________.
a) a five-carbon compound to form an unstable six-carbon compound, which decomposes into two
three-carbon compounds
b) a two-carbon compound to form a three-carbon compound
c) two two-carbon compounds to form a five-carbon compound
d) a five-carbon compound to form a stable six-carbon compound that can be converted directly to
glucose
e) a seven-carbon compound to form two four-carbon compounds

Answer 103

a)

Question 104

33) Glyceraldehyde-3-phosphate (G3P) is produced in the stroma of chloroplasts. Which of the following
statements is most accurate regarding this compound?
a) For every three molecules of CO2 reduced in the Calvin cycle, six molecules of G3P are formed
but only one of these molecules exits the cycle to be used by the plant cell.
b) It is produced from glucose during glycolysis.
c) For every three molecules of CO2, six molecules of G3P are formed but five molecules must be
recycled to regenerate three molecules of RuBP
d) It is a three-carbon sugar.
e) All of the listed responses are correct.

Answer 104

e)

Question 105

36) Why are C4 plants more suited to hot climates than C3 plants?
a) They suspend photosynthesis in the heat.
b) They evolved in cold weather but migrated to the tropics, where they were more suitable.
c) The same cells that bind carbon dioxide perform the Calvin cycle.
d) Unlike C3 plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide
in the leaf is low.
e) They do not close their stomata in hot, dry weather

Answer 105

d)

Question 106

40) Which of the following is the correct sequence for the movement of electrons during the lightdependent reactions of plants?
a) P680  P700  water  NADP+
b) water  P700  NADP+  P680
c) P700  P680  NADP+  water
d) P680  water  P700  NADP+
e) water  P680  P700  NADP+

Answer 106

e)

Question 107

45) Which of the following is mismatched?
a) Photosystem I - uses the P700 molecule in its photocenter
b) PGA - a 3-carbon compound
c) antenna complex - contains hundreds of pigment molecules
d) CAM plants - open their stomata during the day and close them at night to avoid
photorespiration
e) C4 plants - expend ATP to concentrate CO2 in bundle-sheath cells to avoid photorespiration

Answer 107

d)

Question 108

46) Production of one molecule of 3-phosphoglyceraldehyde requires how many turns of the Calvin
cycle?
a) 1
b) 2
c) 3
d) 6
e) 12

Answer 108

c)

Question 109

48) The primary form of sugar transported from the site of photosynthesis to the rest of the plant is:
a) glyceraldehyde 3-phosphate
b) glucose
c) fructose
d) ribulose 1,5-bisphosphate
e) sucrose

Answer 109

e)

Question 110

49) Rubisco:
a) catalyzes the carboxylation of CO2 into a temporary six-carbon molecule (ribulose 1,5-
bisphosphate).
b) initiates photorespiration when the CO2/O2 ratio is low.
c) catalyzes the reduction of two molecules of PGAL to form glucose.
d) all of the above (a-c).
e) two of the answers above.

Answer 110

e)

Question 111

51) Light-driven electron transport in the chloroplast pumps H+
into the intermembrane space between
the outer and inner membranes.
a) True
b) False

Answer 111

F

Question 112

53) If you know the absorption spectrum of a pigment, you can predict the pigment’s color.
a) True
b) False

Answer 112

a)

Question 113

54) For every CO2 molecule fixed by photosynthesis, one molecule of O2 is produced.
a) True
b) False

Answer 113

a)

Question 114

21) In eukaryotes, what is the DNA wrapped around?
a) single-stranded binding proteins
b) sliding clamp
c) polymerase
d) histones

Answer 114

d)

Question 115

23) The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the
basis of the finding that:
a) radioactive phage were found in the pellet
b) radioactive cells were found in the supernatant
c) radioactive sulfur was found inside the cell
d) radioactive phosphorus was found in the cell

Answer 115

d)

Question 116

29) Which base pair requires the least amount of energy to break?
a) G-T
b) A-T
c) T-G
d) T-C
e) G-C

Answer 116

b)

Question 117

30) Which of the following choices represents the structure of DNA from least organized to most
organized?
a) Nucleotide, deoxyribose, nucleotide, DNA double helix, chromatin, nucleosome
b) Deoxyribose, nucleoside, nucleotide, DNA double helix, nucleosome, chromatin
c) Deoxyribose, nucleoside, nucleotide, DNA double helix, chromatin, nucleosome
d) Deoxyribose, nucleoside, chromatin, DNA double helix, nucleotide, nucleosome
e) None of these

Answer 117

b)

Question 118

31) A culture of human tissue is being grown in a lab to study mitosis. A solution containing
radioactively labelled cytosines was added to the culture at the beginning of mitosis, and then
growth was halted at the end of mitosis. Where would the scientists see radioactively labelled
DNA?
a) In every nuclei throughout mitosis
b) No where in the nuclei
c) Only in the nuclei of one of the daughter cells
d) Only in the nuclei of both of the daughter cells
e) None of the answers

Answer 118

b)

Question 119

32) Which answer choice correctly matches the molecule with its function in DNA replication?
a) Topoisomerase—prevents reannealing of DNA during replication;
Single-stranded binding proteins—untangles supercoils
b) DNase—adds nucleotides to new strands;
Single-stranded binding proteins—untangles supercoils
c) Polymerase—adds nucleotides to new strands;
Primase—unzips DNA
d) Topoisomerase—untangles supercoils;
Single-stranded binding proteins—prevents reannealing of DNA during replication
e) Polymerase—adds RNA primers prior to replication;
Primase—adds nucleotides to new strands

Answer 119

d)

Question 120

36) Which of the following are pyrimidines found in the nucleic acid DNA?
a) thymine and cytosine
b) thymine and adenine
c) adenine and guanine
d) guanine and cytosine
e) uracil and guanine

Answer 120

a)

Question 121

37) Which of the following describes a difference between DNA and RNA?
a) RNA molecules generally consist of a single polynucleotide chain, whereas DNA molecules
generally consist of two polynucleotide chains organized into a double helix.
b) Both molecules contain adenine, guanine and cytosine, but DNA also contains thymine and RNA
also contains uracil.
c) They contain different sugars.
d) The first and second listed responses correctly describe differences between DNA and RNA.
e) The first three listed responses correctly describe differences between DNA and RNA.

Answer 121

e)

Question 122

39) Which of the following is true regarding complementary base pairing in DNA and RNA molecules?
a) Although a DNA molecule demonstrates complementary base pairing between two DNA
polynucleotides to form a double helix, an RNA molecule can base-pair only along stretches of
nucleotides in the same RNA molecule, such as in transfer RNA molecules.
b) Complementary base pairing within single strands of DNA and RNA gives them particular threedimensional structures that are necessary for their function.
c) Complementary base pairing promotes an antiparallel orientation in the structure of DNA and
RNA molecules.
d) Although the base pairing between two strands of DNA in a DNA molecule can be thousands to
millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of
nucleotides in the same molecule or between two RNA molecules.
e) None of the listed responses is correct.

Answer 122

d)

Question 123

40) A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If
this composite phage were allowed to infect a bacterium, the phages produced in the host cell would
have __________.
a) the protein and DNA of T2
b) the protein and DNA of T4
c) a mixture of the DNA and proteins of both phages
d) the protein of T4 and the DNA of T2
e) the protein of T2 and the DNA of T4

Answer 123

b)

Question 124

41) Which of the following techniques was most helpful to Watson and Crick in developing their model
for the structure of DNA?
a) electrophoresis
b) radioactive labeling
c) transgenic animals
d) X-ray crystallography
e) cloned DNA

Answer 124

d)

Question 125

44) Which of the following attributes of DNA is most crucial to its accurate duplication?
a) its phosphodiester linkages and complementary strands
b) its specific base pairing through hydrogen bonds
c) its specific sequence of bases
d) its deoxyribose sugar and phosphate groups
e) its helical nature and hydrogen bonding

Answer 125

b)

Question 126

46) Which of the following statements about replication origins is/are correct?
a) The two strands of DNA at the origin of replication are separated, creating a replication bubble.
b) The DNA sequence at the origin of replication is recognized by specific proteins that bind to the
origin.
c) Replication proceeds in both directions from each origin.
d) Bacterial chromosomes have a single origin of replication, but eukaryotic chromosomes have
many origins.
e) All of the listed responses are correct.

Answer 126

e)

Question 127

49) What provides the energy for the polymerization reactions in DNA synthesis?
a) ATP
b) DNA polymerase
c) breaking the hydrogen bonds between complementary DNA strands
d) the deoxyribonucleotide triphosphate substrates

Answer 127

d)

Question 128

53) DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________
of the lagging strands (Okazaki fragments).
a) 3′ end … 3′ end
b) 5′ end … 3′ end
c) 5′ end … 5′ end
d) 3′ end … 5′ end
e) sugar group … phosphate group

Answer 128

a)

Question 129

64) Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes __________.
a) involves two leading strands and no lagging strands
b) has a single origin
c) is semiconservative
d) cannot be completed by DNA polymerase (This is the case because eukaryotic chromosomes are
linear, and DNA polymerase cannot replicate the extreme 3′ end of the template strands.)
e) is error free

Answer 129

d)

Question 130

66) Telomerase __________.
a) speeds cell aging
b) is an enzyme that lengthens telomeres
c) splits telomeres
d) slows the rate of cancer cell growth
e) prevents the loss of centromeric DNA

Answer 130

b)

Question 131

67) In the “beads on a string” structure of unfolded chromatin, the “beads” are __________.
a) genes
b) looped domains
c) heterochromatin
d) nucleoids
e) nucleosomes

Answer 131

e)

Question 132

69) Which of the following represents the order of increasingly higher levels of organization of
chromatin?
a) nucleosome, 30-nm chromatin fiber, looped domain
b) looped domain, 30-nm chromatin fiber, nucleosome
c) nucleosome, looped domain, 30-nm chromatin fiber
d) 30-nm chromatin fiber, nucleosome, looped domain

Answer 132

a)

Question 133

11) How does redundancy of the genetic code make cells more robust to mutations (mutation cause less damage to a cell)?

Answer 133

Codons that specify the same amino acid typically only differ by one nucleotide. In addition, amino acids with chemically similar side chains are encoded by similar codons. This aspect of the genetic code means that a single-nucleotide substitution mutation might either specify the same amino acid and have no effect (a silent mutation – covered in Bio 1). (or may specify a similar amino acid, preventing the protein from being rendered completely nonfunctional.)

Question 134

12) If mRNA is complementary to the DNA template strand and the DNA template strand is complementary to the DNA nontemplate strand, then why are base sequences of mRNA and the DNA nontemplate strand not identical? Could they ever be?

Answer 134

DNA is different from RNA in that T nucleotides in DNA are replaced with U nucleotides in RNA. Therefore, they could never be identical in base sequence.

Question 135

13) Explain how single nucleotide changes can have vastly different effects on protein function.

Answer 135

Nucleotide changes in the third position of codons may not change the amino acid and would have no effect on the protein. Other nucleotide changes that change important amino acids or create or delete start or stop codons would have severe effects on the amino acid sequence of the protein.

Question 136

14) Why are histones effective at coiling DNA?

Answer 136

Histones are positively charged, attracting the negatively charged DNA.

Question 137

15) The AUC and AUA codons in mRNA both specify isoleucine. What feature of the genetic code explains this?
a) complementarity
b) nonsense codons
c) universality
d) redundancy

Answer 137

D

Question 138

16) How many nucleotides are in 12 mRNA codons? a) 12
b) 24 c) 36 d) 48

Answer 138

C

Answer 139

17) Which of the following is not true about RNA?
a) RNA contains adenine
b) RNA can be double stranded
c) RNA contains uracil
d) The sole function of RNA is translation to a protein product
e) RNA contains a five-carbon sugar