Biochemistry Exam 6 - 4/4/11 Questions

Front 1

The daily energy needs for a moderately active person is approximately which of the following?
A) BMR
B) BMR plus an extra 30%
C) BMR plus an extra 60%
D) BMR plus an extra 100%
E) BMR plus an extra 200%

Back 1

C) BMR plus an extra 60%

Front 2

Approximately, what is the normal blood glucose concentration?
A) 0.5 mM
B) 1 mM
C) 3 mM
D) 5 mM
E) 8 mM

Back 2

D) 5 mM

Front 3

Which of these enzymes makes fructose 2,6-bisphosphate?
A) glucokinase
B) hexokinase
C) phosphofructokinase-1
D) phosphofructokinase-2
E) pyruvate kinase

Back 3

D) phosphofructokinase-2

Front 4

Which hormone is increased in direct response to an increase in blood glucose concentration?
A) calcitonin
B) glucagon
C) insulin
D) parathyroid hormone
E) thyroid hormone

Back 4

C) insulin

Front 5

Which fuel source does the brain start to use during starvation?
A) amino acids
B) glucose
C) fatty acids
D) ketone bodies
E) lactate

Back 5

D) ketone bodies

Front 6

Glucagon does which of the following?
A) increases rate of uptake of blood glucose, especially by adipose tissue and skeletal muscle
B) promotes conversion of glucose to glucose 6-phosphate in liver
C) promotes synthesis of glycogen
D) promotes protein synthesis
E) promotes breakdown of triacylglycerol in adipose tissue to fatty acids and glycerol

Back 6

E) promotes breakdown of triacylglycerol in adipose tissue to fatty acids and glycerol

Front 7

An important function of the oxidative phase of the pentose phosphate pathway is to produce:
A) NAD+
B) NADH
C) NADP+
D) NADPH
E) fructose 6-phosphate

Back 7

D) NADPH

Front 8

Which of these statements regarding lipid digestion and absorption is correct?
A) triacylglycerols are taken up directly by the intestinal cell
B) long chain fatty acids pass directly through to the blood
C) only saturated fatty acids are absorbed
D) the intestinal cell releases the absorbed fatty acids in VLDL
E) 2-monoacylglycerol is taken up by the intestinal cell

Back 8

E) 2-monoacylglycerol is taken up by the intestinal cell

Front 9

Which of the following activates acetyl CoA carboxylase?
A) dissociation of the polymer form
B) phosphorylation
C) palmitoyl CoA
D) citrate
E) malonyl CoA

Back 9

D) citrate

Front 10

Insulin is composed of:
A) a single polypeptide chain
B) an A chain and a B chain held together by hydrogen bonds
C) an A chain and a B chain held together by disulfide bonds
D) an A chain, a B chain and a C chain held together by disulfide bonds
E) an A chain, a B chain and a C chain held together by hydrogen bonds

Back 10

C) an A chain and a B chain held together by disulfide bonds

Front 11

Which enzyme does a drug of the statin class inhibit?
A) cyclooxygenase
B) acetyl CoA carboxylase
C) citrate synthase
D) HMG CoA reductase
E) HMG CoA synthetase

Back 11

D) HMG CoA reductase

Front 12

Deficiency of which enzyme can cause hemolytic anemia?
A) glucokinase
B) glucose 6-phosphatase
C) glucose 6-phosphate dehydrogenase
D) UDP-glucose-4-epimerase
E) phosphoglucose isomerase

Back 12

C) glucose 6-phosphate dehydrogenase

Front 13

The function of ApoCII is to:
A) activate lipoprotein lipase
B) activate hormone sensitive lipase
C) bind to receptors to allow for endocytosis of the lipoprotein
D) enable the nascent chylomicrons to enter the lymphatic system
E) enable the newly formed VLDL to leave the hepatocyte

Back 13

A) activate lipoprotein lipase

Front 14

Which of the following inhibits carnitine-palmitoyl transferase I?
A) acetyl CoA
B) malonyl CoA
C) palmitoyl CoA
D) phosphorylation
E) dephosphorylation

Back 14

B) malonyl CoA

Front 15

The α-subunit of the G protein involved in glucagon signaling will activate adenylate cyclase when:
A) it is bound to GDP
B) it is bound to GTP
C) it is bound to the glucagon receptor
D) it is bound to the α and β subunits

Back 15

B) it is bound to GTP

Front 16

After VLDL has had some of the triacylglycerol removed by the action of LPL it becomes:
A) a chylomicron
B) a chylomicron remnant
C) HDL
D) IDL
E) LDL

Back 16

D) IDL

Front 17

The first pentose phosphate to be produced as a result of the oxidative phase of the pentose phosphate pathway is:
A) ribulose 5-phosphate
B) ribose 5-phosphate
C) xylulose 5-phosphate

Back 17

A) ribulose 5-phosphate

Front 18

The conversion of β-hydroxybutyrate to acetoacetate:
A) also produces acetone
B) requires succinyl CoA
C) results in formation of NAD+
D) results in formation of NADH
E) uses 1 ATP

Back 18

D) results in formation of NADH

Front 19

Which of these reactions does NOT occur in adipose tissue?
A) conversion of pyruvate to acetyl CoA
B) conversion of dihydroxyacetone phosphate to glycerol 3-phosphate
C) conversion of glycerol to glycerol 3-phosphate
D) formation of phosphatidic acid
E) synthesis of triacylglycerol

Back 19

C) conversion of glycerol to glycerol 3-phosphate

Front 20

Which of the following is NOT usually a characteristic of type 2 diabetes?
A) associated with insulin resistance
B) can be controlled by a variety of drugs as well as by dietary changes and exercise
C) ketoacidosis is a major complication
D) most common form of diabetes
E) obesity usually present

Back 20

C) ketoacidosis is a major complication

Front 21

Where does cholesterol synthesis occur?
A) cytoplasm
B) endoplasmic reticulum
C) mitochondria
D) nucleus

Back 21

B) endoplasmic reticulum

Front 22

Which hormone mobilizes fuels during acute stress, stimulate glycogen breakdown in muscle and liver, and stimulates fatty acid release from adipose tissue?
A) cortisol
B) epinephrine
C) insulin
D) glucagon

Back 22

B) epinephrine

Front 23

Addition of each CH3CO- group to the growing fatty acyl chain by fatty acid synthase requires how many NADPH + H+?
A) 1
B) 2
C) 3
D) 4
E) 5

Back 23

C) 3

Front 24

The final step in β-oxidation of odd-chain fatty acids results in formation of:
A) acetyl CoA and propionyl CoA
B) methylmalonyl CoA
C) succinyl CoA
D) two acetyl CoA
E) two propionyl CoA

Back 24

A) acetyl CoA and propionyl CoA

Front 25

Which of the following does HDL exchange with VLDL for triacylglycerols?
A) cholesterol
B) cholesterol esters
C) Apo E
D) Apo CII
E) phospholipids

Back 25

B) cholesterol esters

Front 26

The first enzyme in β-oxidation is acyl CoA dehydrogenase which introduces a double bond between the α and β carbons. Which orientation is this double bond in?
A) cis
B) trans

Back 26

B) trans

Front 27

Which enzyme catalyzes malate + NADP+  pyruvate + CO2 + NADPH?
A) malate dehydrogenase
B) malic enzyme
C) pyruvate dehydrogenase
D) pyruvate carboxylase
E) phosphoenolpyruvate carboxykinase

Back 27

B) malic enzyme

Front 28

The major stored source of fuel in the body is:
A) blood glucose
B) fat
C) muscle glycogen
D) liver glycogen
E) protein

Back 28

B) fat

Front 29

Following a typical meal the major source of fuel for the liver is
A) glucose from the diet
B) glucose from stored glycogen
C) dietary lipids
D) ketone bodies
E) protein from the diet

Back 29

A) glucose from the diet

Front 30

The enzyme phosphofructokinase 2
A) converts fructose-6-phosphate to fructose-1,6-bisphosphate
B) converts fructose-6-phosphate to fructose-2,6-bisphosphate
C) converts fructose-1,6-bisphosphate to fructose-2,6-bisphosphate
D) converts fructose to fructose-1-phosphate
E) converts fructose-1-phosphate to glyceraldehydes and dihydroxyacetone phosphate

Back 30

B) converts fructose-6-phosphate to fructose-2,6-bisphosphate

Front 31

Which of the following activates pyruvate dehydrogenase kinase?
A) ADP
B) Ca++
C) NAD+
D) NADH
E) pyruvate

Back 31

D) NADH

Front 32

Glycogen contains:
A) glucose joined by α1,4 glycosidic bonds only
B) glucose joined by α1,4 glycosidic bonds and some α1,6 glycosidic bonds
C) glucose joined by α1,4 glycosidic bonds, and a glycogenin core protein
D) glucose joined by α1,4 glycosidic bonds and some α1,6 glycosidic bonds, and a glycogenin core protein
E) polymerized UDP-glucose

Back 32

D) glucose joined by α1,4 glycosidic bonds and some α1,6 glycosidic bonds, and a glycogenin core protein

Front 33

In regards to glycogen metabolism in the liver, which of the following will occur in response to glucagon?
A) glycogen synthase will be activated
B) phosphorylase will be activated
C) phosphorylase kinase will be inactivated
D) the amount of stored glycogen will increase
E) the rate of UDP-glucose synthesis will be increased

Back 33

B) phosphorylase will be activated

Front 34

Superoxide dismutase catalyzes the conversion of
A) hydrogen peroxide to hydroxyl radical
B) hydrogen peroxide to water and oxygen
C) lipids to lipid peroxides
D) reduced glutathione to oxidized glutathione
E) superoxide and protons to oxygen and hydrogen peroxide

Back 34

E) superoxide and protons to oxygen and hydrogen peroxide

Front 35

The conversion of pyruvate to oxaloacetate by pyruvate carboxylase
A) occurs in the mitochondria
B) requires ATP
C) is the first step in gluconeogenesis from pyruvate
D) is an anapleurotic reaction for the TCA cycle
E) all of the above

Back 35

E) all of the above

Front 36

The pentose phosphate pathway
A) always recycled intermediates back to glycolysis
B) always produces ribose-5-phosphate
C) has the highest activity in muscle
D) operates in the mitochondria
E) produces NADH for biosynthetic reactions

Back 36

B) always produces ribose-5-phosphate

Front 37

The malnutrition state in which there is inadequate caloric intake and inadequate protein is called
A) Kwashiokor
B) Marasmus

Back 37

B) Marasmus

Front 38

Which of the following activates phosphofructokinase-1?
A) ADP
B) citrate
C) fructose-2,6-bisphosphate
D) NADH
E) pyruvate

Back 38

C) fructose-2,6-bisphosphate

Front 39

Epinephrine binding to its α-receptor results in
A) activation of calcium-calmodulin dependent protein kinase by diacylglycerol
B) activation of protein kinase A by calcium
C) activation of phosphorylase kinase by calcium-calmodulin
D) formation of phosphatidylinositol 4,5-bisphosphate and diacylglycerol
E) storage of calcium by the endoplasmic reticulum

Back 39

C) activation of phosphorylase kinase by calcium-calmodulin

Front 40

One of the reasons the body can maintain blood glucose levels in a narrow range even after 5-6 weeks of starvation is
A) because gluconeogenesis from amino acids becomes predominant
B) because gluconeogenesis from lactate and glycerol becomes important
C) because glucose is longer required as a fuel for any tissue
D) because red blood cells start to utilize ketone bodies as a fuel
E) because the brain starts synthesizing its own glucose by gluconeogenesis

Back 40

B) because gluconeogenesis from lactate and glycerol becomes important

Front 41

Which of the following occurs as a result of glucagon binding to its hepatic receptor?
A) activation of glycogen synthase
B) an increase in intracellular calcium
C) association of the regulatory and catalytic subunits of protein kinase A
D) inactivation of phosphorylase
E) inactivation of pyruvate kinase

Back 41

E) inactivation of pyruvate kinase

Front 42

Which of these statements about insulin are true?
A) it contains disulfide bonds
B) it is a peptide hormone
C) it is synthesized as preproinsulin
D) it is secreted from pancreatic β-cells
E) all of the above

Back 42

E) all of the above

Front 43

When blood glucose increases after a meal
A) glucagon secretion increases which results in inactivation of pyruvate kinase
B) gluconeogenesis from alanine is increased
C) insulin is released resulting in an increase in hepatic glycogen production
D) the brain uses ketone bodies as an important energy source
E) the glucose is transported in chylomicrons

Back 43

C) insulin is released resulting in an increase in hepatic glycogen production

Front 44

Which of the following is superoxide?
A) OHº
B) OH-
C) H2O2
D) O2
E) O2-

Back 44

E) O2-

Front 45

Which of the following is the substrate for glycogen synthase?
A) glucose
B) glucose-1-phosphate
C) glucose-6-phosphate
D) UDP-glucose

Back 45

D) UDP-glucose

Front 46

In response to glucagon action, phosphofructokinase-2 (the enzyme and the kinase activity respectively) become:
A) dephosphorylated and active
B) dephosphorylated and inactive
C) phosphorylated and active
D) phosphorylated and inactive

Back 46

D) phosphorylated and inactive

Front 47

In which organelle is glucose-6-phosphatase located?
A) endoplasmic reticulum
B) lysosome
C) mitochondria
D) nucleus
E) peroxisome

Back 47

A) endoplasmic reticulum

Front 48

Which of the following directly causes release of calcium from the endoplasmic reticulum?
A) 1,2-diacylglycerol
B) inositol 1,4,5-triphosphate
C) cAMP
D) phosphatidylinositol 4,5-bisphosphate
E) calmodulin

Back 48

B) inositol 1,4,5-triphosphate

Front 49

Which of these occur as a result of an overnight fast?
A) glucagon ↑, insulin ↓, glycogen synthesis ↑, glycogen degradation ↓
B) glucagon ↓, insulin ↓, glycogen synthesis ↓, glycogen degradation ↑
C) glucagon ↑, insulin ↓, glycogen synthesis ↑, glycogen degradation ↑
D) glucagon ↓, insulin ↑, glycogen synthesis ↓, glycogen degradation ↑
E) glucagon ↑, insulin ↓, glycogen synthesis ↓, glycogen degradation ↑

Back 49

E) glucagon ↑, insulin ↓, glycogen synthesis ↓, glycogen degradation ↑

Front 50

Which of these enzymes found in glycolysis is not reversible and so is not used in gluconeogenesis?
A) phosphoglucose isomerase
B) aldolase
C) glyceraldehydes 3-phosphate dehydrogenase
D) enolase
E) pyruvate kinase

Back 50

E) pyruvate kinase

Front 51

The source of electrons used by neutrophils to make superoxide during the respiratory burst is:
A) FAD(2H)
B) NAD+
C) NADH
D) NADP+
E) NADPH

Back 51

E) NADPH

Front 52

Two important precursors for gluconeogenesis are:
A) glycogen and glycerol
B) lactate and even-numbered chain fatty acids
C) lactate and glycerol
D) alanine and ketone bodies
E) alanine and glycogen

Back 52

C) lactate and glycerol

Front 53

Which of these processes activate phosphorylase kinase?
A) dephosphorylation in response to insulin
B) phosphorylation by cAMP dependent protein kinase
C) phosphorylation by Ca-calmodulin dependent protein kinase
D) phosphorylation by protein kinase C
E) binding to AMP

Back 53

B) phosphorylation by cAMP dependent protein kinase

Front 54

The most serious form of galactosemia (classic galactosemia)
A) is cause by a genetic defect in galactokinase
B) is caused by a genetic defect in aldolase B
C) is caused by a genetic defect in galactose-1-P uridyltransferase
D) requires that lactose in milk be converted in galactose + glucose before it is ingested
E) none of the above

Back 54

C) is caused by a genetic defect in galactose-1-P uridyltransferase

Front 55

One way by which glucagon regulates glycolysis and gluconeogenesis in the liver is by:
A) increasing cyclic-AMP concentration, thereby activating protein kinase A, which leads to the phosphorylation of the glycolytic enzyme phosphofructokinase-1, and this decreasing the activity of this enzyme
B) increasing cyclic-AMP concentration, thereby activating protein kinase A, which leads to the phosphorylation of the glycolytic enzyme pyruvate kinase, thus increasing the activity of this enzyme
C) decreasing the concentration of fructose-2,6-bisP, thereby increasing the activity of phosphofructokinase-1 and decreasing the activity of the gluconeogenic enzyme fructose bisphosphatase-1
D) inducing the synthesis of the enzyme phosphoenolpyruvate carboxykinase (PEPCK)
E) doing all of the above

Back 55

B) increasing cyclic-AMP concentration, thereby activating protein kinase A, which leads to the phosphorylation of the glycolytic enzyme pyruvate kinase, thus increasing the activity of this enzyme

Front 56

Which of the following statements about insulin is FALSE:
A) it activates adenylate cyclase
B) it causes phosphorylation of tyrosines on its receptor
C) it is made in the β-cells of the pancreas
D) it stimulates glycogen storage in the liver
E) secretion is stimulated by elevated blood glucose and amino acids

Back 56

A) it activates adenylate cyclase

Front 57

Synthesis of ketone bodies occurs:
A) by the non-enzymatic conversion of acetyl CoA to acetoactate
B) in response to an increase in blood glucose
C) in starvation
D) mostly in the brain
E) when NADH in the liver is depleted

Back 57

C) in starvation

Front 58

cAMP dependent protein kinase (protein kinase A):
A) is active when the catalytic and regulatory subunits are bound together
B) is activated as a result of glucagon binding to its receptor
C) is activated as a result of insulin binding to its receptor
D) requires calcium for activity
E) requires calmodulin for activity

Back 58

B) is activated as a result of glucagon binding to its receptor

Front 59

The hepatic epinephrine α-receptor causes the release of IP3 and diacylglycerol. What are the consequences?
A) cAMP is increased
B) IP3 inhibits protein kinase C
C) IP3 causes the release of calcium from intracellular stores
D) diacylglycerol activates protein kinase A
E) hepatic glycogen storage is promoted

Back 59

C) IP3 causes the release of calcium from intracellular stores

Front 60

What is the main function of the chylomicron?
A) to act as a store of triacylglycerol
B) to deliver dietary fatty acids to peripheral tissues
C) to deliver fatty acids synthesized in the liver to peripheral tissues
D) to remove cholesterol from cells
E) to return cholesterol to the liver

Back 60

B) to deliver dietary fatty acids to peripheral tissues

Front 61

Ketone bodies:
A) are decreased during fasting
B) are important precursors for gluconeogenesis
C) are made from acetyl CoA
D) are produced in response to insulin
E) are synthesized from glucose during glycolysis

Back 61

C) are made from acetyl CoA