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NBCE sample questions and important info > biochemistry sample questions > Flashcards

biochemistry sample questions Flashcards

1
Q

oxidation of which substance results in ketone bodies?

a. maltose
b. fatty acids
c. glucose
d. aldehyde

A

b. fatty acids

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2
Q

Synthesis of 1 molecule of glucose from lactate requires ____ ATP.

a. 2
b. 3
c. 5
d. 6

A

a. 2

anaerobic glycolysis- lactic acid cycle

lactate back into glucose by the liver= Cori cycle

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3
Q

glucose precursors are primarily derived from ____.

a. fatty acids
b. sterols
c. amino acids
d. ketone bodies

A

c. amino acids

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4
Q

Which of these is a disaccharide with B 1->4 bond?

a. lactose
b. maltose
c. sucrose
d. cellulose

A

a. lactose

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5
Q

which of these is a C-4 epimer of glucose?

a. galactose
b. mannose
c. fructose
d. ribose

A

a. galactose

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6
Q

which of these is a C-2 epimer of glucose?

a. galactose
b. mannose
c. fructose
d. ribose

A

b. mannose

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7
Q

which of these compounds is a simple sugar?

a. maltose
b. glycogen
c. dihydroxyacetone
d. cellulose

A

c. dihydroxyacetone

dihydroxyacetone is a triose which is a simple sugar or monosaccharide

the other trioses are L and D glyceraldehyde

trioses are important in cellular respiration

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8
Q

What is the principal carbohydrate produced by the action of alpha-amylase on dietary starch?

a. alpha-amylose
b. glucose
c. amylopectin
d. maltose

A

d. maltose

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9
Q

The hydrolysis of amylopectin by amylase results in what end product?

a. amylose
b. cellulose
c. sucrose
d. limit dextrin

A

d. limit dextrin

hydrolysis of amylose by amylase results in dextrins

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10
Q

The enzymes that catalyze the breakdown of maltose are secreted by the mucosal cells of the _____.

a. mouth
b. stomach
c. small intestine
d. pancreas

A

c. small intestine

maltase, lactase and sucrase are brush border enzymes of the small intestine

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11
Q

Carbon atoms for fatty acid synthesis are transported to the cytoplasm in the form of ____.

a. succinyl-CoA
b. citrate
c. acetyl-CoA
d. pyruvate

A

c. acetyl-CoA

fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases

succinyl-CoA, citrate and pyruvate are involved in citric acid cycle

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12
Q

The malic enzyme catalyzes the conversion of malate to pyruvate and provides which substance used in fatty acid biosynthesis?

a. oxaloacetate
b. NADPH
c. acetyl-CoA
d. NADH

A

c. acetyl-CoA

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13
Q

Cholesterol is NOT a precursor of _____.

a. aldosterone
b. estrogen
c. Vitamin D
d. lecithin

A

d. lecithin

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14
Q

Triacylglycerols are transported from intestinal cells to adipose cells within _____.

a. chylomicrons
b. VLDLs
c. LDLs
d. HDLs

A

a. chylomicrons

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15
Q

The bonding between the fatty acid and the glycerol in a 2-monoacylglycerol is best described as which of these?

a. glycosidic bond
b. ester linkage
c. peptide linkage
d. anhydride bond

A

b. ester linkage

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16
Q

A lack of lipoprotein lipase results in ____.

a. a decrease in free fatty acids released by adipocytes
b. an elevated level of chylomicrons following a high fat meal
c. overproduction of LDLs
d. overproduction of HDLs

A

b. an elevated level of chylomicrons following a high fat meal

known as familial chylomicronemia syndrome- autosomal recessive

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17
Q

Which of these is a good source of omega-3 fatty acids?

a. shrimp
b. butter
c. salmon
d. chicken

A

c. salmon

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18
Q

Which type of fatty acid is abundant in olive oil?

a. saturated
b. monounsaturated
c. short-chain
d. polyunsaturated

A

b. monounsaturated

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19
Q

Dietary lipids are converted into _____ by pancreatic lipase

a. lipoproteins
b. 2-monoacylglyercols
c. bile salts
d. cholesterol

A

b. 2-monoacylglycerols

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20
Q

Which of these actions occurs during the alanine cycle?

a. Pyruvate converted to glucose in the liver
b. Pyruvate transaminated to glutamate in liver
c. Pyruvate transported from skeletal muscle to liver
d. Gluconeogenesis occurs in the skeletal muscle

A

c. Pyruvate transported from skeletal muscle to liver

called the Cahill cycle; pyruvate is transaminated to form alanine not glutamate

similar to Cori cycle, but Cori cycle uses lactate

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21
Q

Arginase catalyzes the enzymatic conversion of arginine into ____ and urea

a. ornithine
b. alanine
c. lysine
d. citrulline

A

a. ornithine

arginase is a manganese containing enzyme which is the final enzyme in the urea cycle

arginine + H2O -> ornithine + urea

22
Q

Acetyl-CoA derived from the oxidative breakdown of amino acids is completely oxidized to CO2 through a series of reactions known as the _____.

a. pentose-phosphate pathway
b. electron transport chain
c. glycolytic pathway
d. TCA

A

d. TCA

23
Q

Bile acids contain a carboxyl group in their side chain that is often bound in amide linkage with _____.

a. phenylalanine
b. tryptophan
c. histidine
d. taurine

A

d. taurine

or glycine

24
Q

Which of these is characteristic of myoglobin?

a. it is a tetramer
b. it is present in erythrocytes
c. it has a fibrous quality
d. it is a single polypeptide

A

d. it is a single polypeptide

25
Q

which of these is not an essential amino acid?

a. alanine
b. serine
c. lysine
d. asparagine

A

c. lysine

26
Q

Which enzyme is controlled by product inhibition allowing skeletal muscle cells to accumulate glucose?

a. hexokinase
b. glucokinase
c. pyruvate kinase
d. phosphofructokinase

A

a. hexokinase

high affinity for glucose (low Km)

27
Q

The toxicity of many pesticides results from ___ enzyme inhibition

a. irreversible
b. competitive
c. synergistic
d. allosteric

A

b. competitive

28
Q

When the equilibrium constant for a reaction is equal to 1, then the standard free-energy charge for the reaction is ______.

a. -1.36
b. 0.00
c. 1.36
d. 2.73

A

b. 0.00

29
Q

Saturation levels of substrate concentration in an enzyme-catalyzed reaction cause the progress curve to display ______.

a. zero-order kinetics
b. first-order kinetics
c. negative cooperativity
d. feedback inhibition

A

b. zero-order kinetics

30
Q

The anabolism and catabolism phases of protein metabolism are both affected by which of these?

a. estrogen
b. glucagon
c. testosterone
d. glucocorticoids

A

b. glucagon

31
Q

Which of these hormones enhances the activity of glycogen phosphorylase in skeletal muscle?

a. epinephrine
b. testosterone
c. estrogen
d. aldosterone

A

a. epinephrine

also glucagon

32
Q

Which of these hormones activates glycogenolysis while inhibiting glycogenesis and glycolysis to maximize the release of glucose?

a. insulin
b. glucagon
c. cortisol
d. aldosterone

A

b. glucagon

33
Q

Glucagon activates which enzyme in the plasma membrane of hepatocytes?

a. phosphoprotein phosphatase
b. glycogen synthase
c. protein kinase
d. adenylate cyclase

A

d. adenylate cyclase

adenylate cyclase makes cAMP which activates protein kinase A

34
Q

Which of these factors characterizes gout?

a. overproduction of purine nucleotides
b. tyronase deficiency
c. adenine and guanine biosynthesis deficiency
d. urea cycle hyperactivity

A

c. adenine and guanine biosynthesis deficiency

also underproduction of purine nucleotides and decrease in urea cycle

35
Q

One-carbon transfers during the production of purines and pyrimidines are dependent on_____.

a. biotin
b. thiamine
c. folic acid
d. tocopherols

A

c. folic acid

36
Q

Which enzyme catalyzes peptide bond formation during protein synthesis at the ribosome?

a. RNA polyamerase
b. DNA ligase
c. peptidyl transferase
d. peptidyl dehydratase

A

c. peptidyl transferase

37
Q

Which amino acid initiates protein synthesis in humans?

a. serine
b. methionine
c. leucine
d. isoleucine

A

b. methionine

38
Q

The primary function of vitamin D is to regulate the absorption and metabolism of which minerals?

a. sodium and potassium
b. calcium and phosphorus
c. iron and phosphorus
d. sodium and calcium

A

b. calcium and phosphorus

39
Q

Which mineral is required for activity of most glycolytic enzymes?

a. copper
b. magnesium
c. cobalt
d. sulfur

A

b. magnesium

40
Q

Which coenzyme is required for oxidative decarboxylation processes?

a. biotin
b. cobalamin
c. thiamine pyrophosphate
d. pyridoxal phosphate

A

c. thiamine pyrophosphate

41
Q

Vitamin K is essential for the synthesis of ____.

a. fibrinogen
b. hemoglobin
c. rhodopsin
d. prothrombin

A

d. prothrombin

42
Q

Dietary supplementation of therapeutic amounts of folic acid may be detrimental because it can ___.

a. cause kidney stones
b. mask a B12 deficiency
c. damage the liver
d. inhibit absorption of other vitamins

A

b. mask a B12 deficiency

can also promote tumor growth and cause zinc deficiency

43
Q

Which of these foods are the richest sources of vitamin E?

a. root vegetables
b. vegetable oils
c. fruits
d. fish

A

b. vegetable oils

44
Q

What vitamin is synthesized by intestinal flora?

a. A
b. D
c. E
d. K

A

d. K

45
Q

It is possible for which vitamin to be synthesized from tryptophan?

a. thiamine
b. cyanocobalamin
c. niacin
d. pyroxidine

A

c. niacin

46
Q

which of these is characteristic of a spontaneous reaction?

a. standard free energy is positive
b. an enzyme has catalyzed the reaction
c. Gibbs’s free energy is negative
d. Keq is greater than 1

A

c. Gibbs’s free energy is negative

-delta G is favorable with a large K
+delta G is not favorable with low K
delta G 0= equilibrium

47
Q

The phosphate groups of ATP are linked by ___ bonds.

a. phosphoanhydride
b. phosphate amide
c. phosphodiester
d. hydrogen

A

a. phosphoanhydride

48
Q

Which compound catalyzes the formation of GTP in the tricarboxylic acid cycle?

a. succinate dehydrogenase
b. alpha-ketoglutarate dehydrogenase
c. malate dehydrogenase
d. succinate thiokinase

A

d. succinate thiokinase

49
Q

In the tricarboxylic acid cycle, isocitrate dehydrogenase converts isocitrate to ____.

a. fumarate
b. a-ketoglutarate
c. succinyl-CoA
d. citrate

A

b. a-ketoglutarate

50
Q

Which complex of the electron transport system contains copper?

a. NADH dehydrogenase
b. succinate dehydrogenase
c. ubiquinol-cytochrome c oxidoreductase
d. cytochrome c oxidase

A

d. cytochrome c oxidase

held by copper

NADH dehydrogenase- FMN

NBCE sample questions and important info (27 decks)

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