BIOC 385 Final Exam Question Set

The Biosphere 2 project, in Tucson, Arizona, was an experiment involving a large sealed terrarium with humans and photosynthetic plants living in balance. Why did the project have to be interrupted after only a few months?
a) Levels of CO2 rose to dangerous levels.
b) The humans ran out of food.
c) The plants stopped producing oxygen.
d) The rate of photosynthesis was too high.

The Biosphere 2 project, in Tucson, Arizona, was an experiment involving a large sealed terrarium with humans and photosynthetic plants living in balance. Why did the project have to be interrupted after only a few months?
a) Levels of CO2 rose to dangerous levels.
b) The humans ran out of food.
c) The plants stopped producing oxygen.
d) The rate of photosynthesis was too high.

a) Levels of CO2 rose to dangerous levels.

The __________ is driven directly by photons from the sun in photosynthesis light reactions.
a) pumping of protons
b) synthesis of ATP
c) transfer of electrons
d) synthesis of glucose

c) transfer of electrons

Heme and chlorophyll have similar overall structures. What is common between the two molecules?
a) color
b) hydrophobic tail
c) polycyclic planar structure
d) metal ion found at their center

c) polycyclic planar structure

Chlorophyll absorbs light energy efficiently because of the
a) metal ion in the center of the molecule.
b) ring structure.
c )planar structure.
d) alternating double and single bonds.

d) alternating double and single bonds.

Which of the following is a photosynthetic light harvesting pigment?
a) FeS cluster
b) NADPH
c) plastoquinone
d) β-carotene

d) β-carotene

Approximately how many light-harvesting chromophores are found per photosystem enzyme, such as in PSI or PSII?
a) 2
b) about a dozen
c) about 100 to 200
d) about 1000 to 2000

c) about 100 to 200

The following picture is an example of what phenomenon?
a) resonance energy transfer
b) electron transfer
c) photoexcitation
d) fluorescence

a) resonance energy transfer

Which of the following is an electron transfer molecule in photosynthesis light reactions?
a) plastoquinone
b) photon
c) paraquat
d) ATP

a) plastoquinone

The photosynthetic Z scheme describes the
a) synthesis of glucose from CO2.
b) movement of electrons driven by the absorption of light energy.
c) production of O2.
d) reduction of NADPH.

b) movement of electrons driven by the absorption of light energy.

The primary difference between ATP synthesis during the photosynthetic light reactions and ATP synthesis in the mitochondrial electron transport chain is the
a) cellular location of the proton motive force.
b) enzyme catalyzing the ATP synthesis.
c) number of ATP produced per 360 rotation of the F1 subunit of ATP synthase.
d) number of NADPH required to produce ATP.

a) cellular location of the proton motive force.

In the chloroplasts, photosystem I (PSI) and photosystem II (PSII) are known to localize in different regions. PSI generally localizes in the __________, whereas PSII localizes in the __________.
a) thylakoid lumen; thylakoid grana
b) thylakoid lamellae; thylakoid grana
c) stroma; thylakoid lumen
d) thylakoid grana; thylakoid lamellae

b) thylakoid lamellae; thylakoid grana

In what location of the cell does the Calvin cycle occur?
a) chloroplast grana
b) thylakoid lumen
c) chloroplast stroma
d) cytoplasm

c) chloroplast stroma

The Calvin cycle requires which species from the light reactions?
a) ATP and NADPH
b) reducing electrons
c) CO2 and ATP
d) NADH and FADH2

a) ATP and NADPH

The first stage of the three-stage Calvin cycle
a) generates CO2.
b) uses ATP and NADPH from the light reactions.
c) occurs in the plant cell cytoplasm.
d) is catalyzed by the enzyme rubisco.

d) is catalyzed by the enzyme rubisco.

The formation of one net glyceraldehyde-3-phosphate during the net Calvin cycle reactions requires __________ NADPH and __________ ATP.
a) 3; 3
b) 3; 6
c) 6; 6
d) 6; 9

d) 6; 9

What is the name of the enzyme that catalyzes the reaction shown below?
a) ribulose bisphosphate carboxylase
b) acetyl-CoA carboxylase
c) glyceraldehyde-3-phosphate dehydrogenase
d) pyruvate carboxylase

a) ribulose bisphosphate carboxylase

Transketolase requires the coenzyme
a) cobalamin (vitamin B12).
b) pyridoxal phosphate.
c) tetrahydrofolic acid.
d) thiamine pyrophosphate.

d) thiamine pyrophosphate.

Which cell type in C4 plants is isolated from O2 exposure as they perform Calvin cycle reactions?
a) Hatch-Slack cells
b) bundle sheath cells
c) guard cells
d) mesophyll cells

b) bundle sheath cells

Which of the following is true of the glyoxylate cycle?
a) It allows plants to produce glucose from fats and two-carbon molecules like acetate.
b) It occurs in plant cells as an alternative to photosynthesis.
c) It bypasses all regulated steps of the TCA cycle.
d) It results in a net production of ATP and NADH without proceeding through the TCA cycle.

a) It allows plants to produce glucose from fats and two-carbon molecules like acetate.

The glyoxylate cycle reaction shown below is catalyzed by which enzyme class?
a) lyase
b) hydrolase
c) transferase
d) oxidoreductase

a) lyase

Which of the following is classified as a monosaccharide?
a) sucrose
b) glucose
c) lactose
d) maltose

b) glucose

One of the functions of simple sugars includes
a) enzymatically removing glycans through hydrolysis reactions.
b) functioning as a structural component in invertebrate exoskeletons.
c) acting as metabolic intermediates in energy conversion pathways.
d) enzymatically linking glycans to proteins and lipids.

c) acting as metabolic intermediates in energy conversion pathways.

Which of the following oligosaccharides are found in high abundance in some types of vegetables and have been known to cause intestinal distress?
a) lacto-N-tetraose
b) verbascose
c) amylose
d) amylopectin

b) verbascose

The product Beano contains __________, which helps humans digest raffinose-series oligosaccharides.
a) a-galactosidase
b) B-galactosidase
c) lactase
d) amylase

a) a-galactosidase

The image below shows a(n) __________ glycosidic bond.
a) a-1,4-
b) B-1,4-
c) a-1,6-
d) B-1,6-

b) B-1,4-

What type of bond is responsible for the rigid nature of the polysaccharide fibril structure?
a) London forces
b) ionic bonds
c) covalent bonds
d) hydrogen bonds

d) hydrogen bonds

Compared with glycogen, amylopectin contains __________ glycosidic bonds.
a) more a-1,6
b) fewer a-1,6
c) only a-1,4
d) only a-1,6

b) fewer a-1,6

Compared with amylopectin, amylose has __________ glycosidic bonds.
a) more a-1,6
b) fewer a-1,6
c) only a-1,4
d) only a-1,6

c) only a-1,4

The glycan group on glycoproteins and glycolipids on the red blood cells all contain the glycan subgroup(s)
a) O.
b) Gal.
c) GalNAc.
d) Gal and GalNAc.

a) O.

Crystal violet stains Gram-positive bacteria because Gram-positive bacteria have a(n)
a) outer membrane layer that collapses, trapping the crystal violet molecules.
b) thinner peptidoglycan layer that allows the crystal violet molecules to pass through the pores.
c) thinner peptidoglycan layer that collapses, trapping the crystal violet molecules.
d) thicker peptidoglycan layer that collapses, trapping the crystal violet molecules.

d) thicker peptidoglycan layer that collapses, trapping the crystal violet molecules.

Gram-negative bacteria resist staining with crystal violet because Gram-negative bacteria have a(n)
a) outer membrane layer that collapses, releasing the crystal violet molecules.
b) thinner peptidoglycan layer that does not retain the crystal violet molecules.
c) thinner peptidoglycan layer that collapses, releasing the crystal violet molecules.
d) thicker peptidoglycan layer that collapses, releasing the crystal violet molecules.

b) thinner peptidoglycan layer that does not retain the crystal violet molecules.

Which enzyme does penicillin target in bacteria?
a) B-lactamase
b) peptidase
c) transpeptidase
d) a-galactosidase

c) transpeptidase

Which amino acid does penicillin form a complex with on transpeptidase?
a) aspartic acid
b) lysine
c) alanine
d) serine

d) serine

Penicillin kills bacteria by inhibiting the biosynthesis of the cell wall. How does penicillin cause the inhibition?
a) The transpeptidase of the bacteria binds to methicillin.
b) The carbonyl carbon of the B-lactam ring of penicillin binds to transpeptidase.
c) The B-lactam ring in penicillin is hydrolyzed.
d) The glycine in transpeptidase binds to penicillin.

b) The carbonyl carbon of the B-lactam ring of penicillin binds to transpeptidase.

Both methicillin and penicillin are inactive when exposed to
a) transpeptidase.
b) transpeptidase and B-lactamase.
c) B-lactamase.
d) variant transpeptidase.

d) variant transpeptidase.

A B-elimination reaction is used in glycan characterization to
a) label the antibody arrays.
b) fluorescently label glycoproteins.
c) cleave the O-linked glycans.
d) cleave the N-linked glycans.

c) cleave the O-linked glycans.

Glycan arrays can be coupled with __________ to qualitatively compare fractionated cell extracts from different sources.
a) MALDI-TOF
b) HPLC
c) size exclusion chromatography
d) mass spectrometry

b) HPLC

To detect lectins on the surface of pathogenic and nonpathogenic bacteria, __________ would be used.
a) HPLC
b) MALDI-TOF
c) a glycan array
d) column chromatography

c) a glycan array

The pentose phosphate pathway
a) resembles the TCA cycle in that it couples the loss of CO2 with the formation of NADH.
b) allows 5C sugars to converge with or diverge from the glycolysis pathway.
c) contains 2C, 3C, 4C, 5C, 6C, and 7C sugar molecules.
d) enables the production of ATP from glucose.

b) allows 5C sugars to converge with or diverge from the glycolysis pathway.

Which is the substrate or product of the reactions that comprise the oxidative branch of the pentose phosphate pathway?
a) sedoheptulose-7-phosphate
b) glyceraldehyde-3-phosphate
c) ribulose-5-phosphate
d) ribose-5-phosphate

c) ribulose-5-phosphate

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?
a) ATP
b) NADPH
c) fructose-6-phosphate
d) CO2

c) fructose-6-phosphate

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?
a) 0; 0
b) 0; 2
c) 2; 0
d) 2; 2

b) 0; 2

Which enzyme in the pentose phosphate pathway is regulated to control flux through the pathway?
a) glucose-6-phosphate dehydrogenase
b) transaldolase
c) 6-phosphogluconate dehydrogenase
d) ribulose-5-phosphate epimerase

a) glucose-6-phosphate dehydrogenase

If the ratio of NADP+ to NADPH were high, the
a) net production of ATP would occur.
b) pentose phosphate pathway oxidative phase would be activated.
c) cellular levels of nucleotides would have to increase from an activated pentose phosphate pathway.
d) pentose phosphate pathway would be inhibited.

b) pentose phosphate pathway oxidative phase would be activated.

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?
a) Higher than normal levels of NADPH would accumulate.
b) They would not have the ability to regenerate reduced glutathione as rapidly.
c) They would rapidly neutralize cellular levels of H2O2 and other reactive oxygen species.
d) They would compensate with higher than normal levels of pentose phosphate pathway activity.

b) They would not have the ability to regenerate reduced glutathione as rapidly.

The conversion of pyruvate to phosphoenolpyruvate (PEP) in gluconeogenesis
a) requires the net input of two equivalents of NADH.
b) occurs in two steps and is catalyzed by the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase.
c) is a thermodynamically spontaneous reaction that gives rise to a stable product.
d) requires lactate as a precursor.

b) occurs in two steps and is catalyzed by the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase.

What molecules are missing from boxes in the gluconeogenesis reaction shown below?
a) Ser-Pi; Ser-Pi
b) H2O; Pi
c) ADP; ATP
d) ATP; ADP

b) H2O; Pi

Which enzyme in the glycolysis pathway catalyzes a reaction that requires two enzymes to reverse in the gluconeogenesis pathway?
a) pyruvate kinase
b) phosphofructokinase I
c) pyruvate dehydrogenase
d) glycogen phosphorylase

a) pyruvate kinase

Of the four molecules listed below, three of them reciprocally regulate phosphofructokinase 1 (PFK1) and fructose-1,6-bisphosphatase. Which molecule does NOT fit?
a) pyruvate
b) fructose-2,6-bisphosphate
c) citrate
d) AMP

a) pyruvate

The hormone insulin activates phosphofructokinase 2 (2PFK2). This leads to a(n) __________ in concentration of fructose 2,6 bisphosphate, which favors the __________ pathway.
a) increase; glycolysis
b) increase; gluconeogenesis
c) decrease; glycolysis
d) decrease; gluconeogenesis

a) increase; glycolysis

Which molecule allosterically activates pyruvate carboxylase?
a) AMP
b) NAD+
c) epinephrine
d) acetyl-CoA

d) acetyl-CoA

Which of the following molecules would activate phosphofructokinase 1 (PFK1)?
a) NADH
b) AMP
c) ATP
d) pyruvate

b) AMP

Which of the following molecules would inhibit the last reaction of glycolysis?
a) ATP
b) glucose
c) AMP
d) NAD+

a) ATP

What triggers the Cori cycle?
a) a buildup of cellular NAD+
b) oxygen-limited working muscle cells
c) low levels of glucose in the muscle cells
d) elevated glucagon levels

b) oxygen-limited working muscle cells

In the elongation of glycogen, activated glucose units are attached to which hydroxyl of the terminal residue of the growing glycogen chain?
a) C-1
b) C-3
c) C-4
d) C-6

c) C-4

In the glycogenesis pathway, what is the leaving group in the last step where glucose is added to the growing glycogen chain?
a) UDP-glucose
b) pi
c) glucose-1-phosphate
d) UDP

d) UDP

In the glycogenesis pathway, which enzyme catalyzes the formation of (1,6) linkages?
a) debranching enzyme
b) glycogen synthase
c) glycogen phosphorylase
d) branching enzyme

d) branching enzyme

In the glycogenesis pathway, the role of the glucose-6-phosphate isomerization reaction is to
a) create a more stable intermediate for the subsequent reaction.
b) decrease the concentration of glucose-6-phosphate, thereby driving the pathway forward.
c) ensure that the charged molecule stays in the cell.
d) prepare the anomeric carbon for nucleophilic attack.

d) prepare the anomeric carbon for nucleophilic attack.

In the breakdown of glycogen, the debranching enzyme catalyzes the formation of
a) glucose-1-phosphate.
b) glucose.
c) a(1,6) branched glycogen.
d) glucose-6-phosphate.

b) glucose.

The debranching enzyme does NOT catalyze the
a) formation of a(1,6) linkages.
b) cleavage of a(1,6) linkages.
c) formation of a(1,4) linkages.
d) cleavage of a(1,4) linkages.

a) formation of a(1,6) linkages.

What class of biomolecule is glycogenin?
a) hormone
b) carbohydrate
c) enzyme
d) lipid

c) enzyme

Why is it important that muscle cells are unresponsive to glucagon?
a) Muscle cells store glycogen for its own energy needs and not the needs of other tissues.
b) The muscles do not store glycogen.
c) The muscles release glucose to other tissues in need.
d) Muscle cells respond to insulin instead.

a) Muscle cells store glycogen for its own energy needs and not the needs of other tissues.

Predict the structure of a fatty acid that is trans 16:1 (9).

Predict the fatty acid with the lowest melting point.
a) trans 14:1 (7)
b )cis 14:2 (7,9)
c) trans 14:2 (7,9)
d) cis 14:3 (7,9,11)

d) cis 14:3 (7,9,11)

One disadvantage of using partial hydrogenation in the food industry is that
a) the shelf life of the oils is not as long.
b) trans fats are formed during the process.
c) the oils tend to become rancid and have foul odors.
d) the oils cost more than animal fats.

b) trans fats are formed during the process.

Predict the essential -6 fatty acid.
a) trans 18:2 (9,12)
b) cis 18:2 (9,12)
c) trans 18:2 (6,9)
d) cis 18:2 (6,9)

b) cis 18:2 (9,12)

During the process of saponification, fatty acid molecules are released from triacylglycerols by treatment(s) with a strong
a) base.
b) acid.
c) base and heat.
d) acid and heat.

c) base and heat.

Spices such as eugenol are added to oils to enhance the flavor because of
a) hydrogen bonds.
b) dipole-dipole interactions.
c) hydrophilic interactions.
d) hydrophobic interactions.

d) hydrophobic interactions.

The water-soluble enzyme in the small intestine that hydrolyzes the acyl ester bonds in triacylglycerols is
a) adipocyte.
b) albumin.
c) lipase.
d) colipase.

c) lipase.

Which particles transport triacylglycerols to adipose tissue for storage?
a) apolipoproteins
b) adipocytes
c) chylomicrons
d) perilipin

c) chylomicrons

Chylomicrons are produced in
a) liver cells.
b) intestinal epithelial cells.
c) stomach cells.
d) adipocytes.

b) intestinal epithelial cells.

Which is the step in glucagon signaling where adipose triglyceride lipase mediates a reaction?1. A hydrolysis reaction cleaves a fatty acid from the stored triacylglycerols to generate diacylglycerol and a fatty acid.2. Perilipin is phosphorylated on the surface of lipid droplets.3. Albumin transports the free fatty acid.4. A GDP-GTP exchange stimulates cyclic AMP production by the enzyme adenylate cyclase.
a) 1
b) 2
c) 3
d) 4

a) 1

The outer layer of the plasma membrane of human erythrocytes contains mostly __________ lipids.
a) phosphatidylinositol
b) phosphatidylserine
c) phosphatidylcholine
d) phosphatidylethanolamine

c) phosphatidylcholine

The inner layer of the plasma membrane of human erythrocytes contains mostly __________ lipids.
a) phosphatidylserine
b) ganglioside
c) phosphatidylcholine
d) sphingomyelin

a) phosphatidylserine

Compared with other areas of the membrane, lipid rafts contain more
a) sphingolipids.
b) phosphatidylcholine.
c) phosphatidylinositol.
d) gangliosides.

a) sphingolipids.

The addition of phosphocholine to ceramides generates
a) glycerophospholipids.
b) gangliosides.
c) cerebrosides.
d) sphingomyelin.

d) sphingomyelin.

Which of the following membranes would have the greatest fluidity based on the following percentage of cholesterol in the membrane?
a) 10%
b) 25%
c) 30%
d) 40%

a) 10%

Which of the following molecules aid in the absorption of dietary lipids?
a) prostaglandin
b) cortisol
c) glycocholate
d) aldosterone

c) glycocholate

Cortisol is a glucocorticoid that regulates
a) blood pressure.
b) ion transport in the kidneys.
c) testosterone.
d) liver metabolism.

d) liver metabolism.

A patient is having problems regulating blood pressure and has poor kidney function. Which steroid could be responsible for this?
a) progesterone
b) cortisol
c) aldosterone
d) estradiol

c) aldosterone

Which steroid hormone is synthesized in the corpus luteum?
a) cortisol
b) progesterone
c) testosterone
d) estradiol

b) progesterone

7-Dehydrocholesterol is converted to cholecalciferol (Vitamin D3) by
a) P450C1 hydroxylase.
b) P450C12 hydroxylase.
c) P450C25 hydroxylase.
d) ultraviolet light.

d) ultraviolet light.

Vitamin D3 is converted to 25-hydroxyvitamin D3 in the __________ cells.
a) skin
b) kidney
c) muscle
d) liver

d) liver

25-Hydroxyvitamin D3 is converted to 1,25-hydroxyvitamin D3 by
a) P450C1 hydroxylase.
b) P450C12 hydroxylase.
c) P450C25 hydroxylase.
d) ultraviolet light.

a) P450C1 hydroxylase.

Which eicosanoid modulates the secretion of proteoglycans that protects the stomach lining from the effects of low pH?
a) prostaglandin
b) prostacyclin
c) thromboxane
d) leukotriene

a) prostaglandin

Which eicosanoid regulates blood vessel constriction?
a) prostaglandin
b) prostacyclin
c) thromboxane
d) leukotriene

c) thromboxane

How many passes through the fatty acid oxidation pathway are required to degrade palmitic acid?
a) 1
b) 7
c) 8
d) 16

b) 7

What precursors are required for the breakdown of palmitate?
a) 14 ATP and 14 NADH
b) ATP and CoA
c) acetyl-CoA
d) NADH and FADH2

b) ATP and CoA

What is the key enzyme involved in priming fatty acids for degradation?
a) acetyl-CoA carboxylase
b) fatty acyl-CoA synthetase
c) carnitine acyltransferase I
d) fatty acyl hydrolase

b) fatty acyl-CoA synthetase

Which enzyme catalyzes the modification of a fatty acid, so that it can be transported into the mitochondria for oxidation?
a) acyl-CoA dehydrogenase
b) acetyl-CoA carboxylase
c) fatty acyl-CoA synthetase
d) carnitine acyltransferase I

d) carnitine acyltransferase I

Which molecule is used to transport fatty-acyl groups into the mitochondria?
a) CoA-SH
b) ATP
c) biotin
d) carnitine

d) carnitine

What enzyme class catalyzes the following reaction? (Note that there may be some missing reactants and products.)
a) lyase
b) hydrolase
c) transferase
d) dehydrogenase

d) dehydrogenase

How many more passes through B-oxidation does the saturated fat stearic acid (18:0) require, compared with the monounsaturated fat oleic acid (18:1)?
a) 0
b) 1
c) 2
d) 17

a) 0

The B-oxidation of mono- and polyunsaturated fatty acids
a) requires an extra cycle through the pathway.
b) involves the reduction of the double bonds and then the continuation of B-oxidation.
c) yields succinyl-CoA.
d) involves isomerization and in some cases reduction of the double bonds before the continuation of B-oxidation.

d) involves isomerization and in some cases reduction of the double bonds before the continuation of B-oxidation.

How do we deal with the double bonds during the degradation of unsaturated fatty acids?
a) Convert the three-carbon propionyl-CoA to succinyl-CoA and feed it into the TCA cycle.
b) Converge them with the TCA cycle to produce acetyl-CoAs.
c) Isomerize the position of the double bonds to converge them with the B-oxidation pathway.
d) Reduce them to single bonds and feed the saturated fatty acid into the B-oxidation pathway.

c) Isomerize the position of the double bonds to converge them with the B-oxidation pathway.

What extra enzyme types are often required in the degradation of polyunsaturated fats by the B-oxidation pathway?
a) reductase and isomerase
b) hydrolase and isomerase
c) oxidoreductase and reductase
d) synthase and isomerase

a) reductase and isomerase

Which is found in the ketone body pathway?
a) succinyl-CoA.
b) propionyl-CoA.
c) dihydroxyacetone phosphate.
d) hydroxybutyrate.

d) hydroxybutyrate.

A difference between FA synthesis and -oxidation is that FA synthesis __________, whereas B-oxidation __________.
a) reactions use ATP; reactions directly yield ATP
b) occurs in the mitochondria; takes place in the cytoplasm
c) uses NADH; uses NADPH
d) uses acyl-ACP; uses acyl-CoA

d) uses acyl-ACP; uses acyl-CoA

The same four reactions that are central to the -oxidation pathway are also present in the fatty acid synthesis pathway, except they are reversed. What is a key difference between the four reactions in these two pathways?
a) One set of reactions synthesizes an ATP, whereas the other set uses an ATP.
b) One set occurs in the muscle, whereas the second pathway occurs in the liver.
c) One pathway adds three carbon atoms at a time, whereas the other removes two carbons.
d) Four enzymes are used in one, whereas one enzyme is used in the other.

d) Four enzymes are used in one, whereas one enzyme is used in the other.

What enzyme catalyzes the following reaction in the first step of fatty acid synthesis?
a) fatty acyl-CoA synthetase
b) acetyl-CoA carboxylase
c) fatty acid synthase
d) fatty acyl-CoA dehydrogenase

b) acetyl-CoA carboxylase