MCB

Question 1

All of the following are true about Henderson-Hasselbalch equation except

Accepted Answer

None of the above

Answer

If pKa < pH then A- > HA i.e. dissociated

Answer

if pKa > pH, then HA > A- i.e. not dissociated

Answer

When Concentration of A- and HA are equal then pH=pKa

Question 2

All of the following are sequence of events in the transport of bicarbonate

Accepted Answer

H+ is taken up by the Hemoglobin and HCO3- is exchanged for PO4-

Answer

Tissues like liver generate CO2 by cellular respiration

Answer

CO2 + H2O in the presence of carbonic anhydrase in RBC results in H2CO3

Answer

H2CO3 dissociates into H+ and HCO3-

Question 3

All of the following regarding Oxy-Hb dissociation curve are true except?

Accepted Answer

Hemoglobin and Myoglobin both have the same type of curve

Answer

Shift to the right means more O2 is released to the tissues

Answer

Low pH, high PCO2, increased H+ concentration and increased 2,3DPG all cause a shift to the right

Question 4

Proton binding by Hb reduces oxygen affinity is called the Bohr effect

Answer

true

Question 5

Oxygen has >200 times greater affinity for Hb than CO

Answer

true

Question 6

all of the following regarding enzymes are true except?

Accepted Answer

Velocity continues to increase with increasing substrate concentration

Answer

The velocity of all enzyme reactions is dependent on the concentration of the Substrate

Answer

The initial velocity of product formation (vi) proportional to Concentration of ES

Question 7

In competitive inhibition Vmax is decreased and Km is unchanged, in noncompetitive inhibition Vmax remains unchanged and Km is changed

Answer

true

Question 8

All of the following regarding allosteric enzyme are correct except

Accepted Answer

None of the above

Answer

Regulation via allosterism can be more powerful since activators don't use catalytic site

Answer

Inhibitors have stronger effect than at active site

Answer

changes can be rapid

Answer

Allosteric enzyme has a sigmoid curve

Answer

all of the above

Question 9

All of the following are irreversible steps in Glycolysis except

Accepted Answer

Glyceraldehyde 3 phosphate to 1,3 Bisphosphoglycerate

Answer

Glucose to Glucose 6 phosphate

Answer

Fructose 6 phosphate to Fructose 1,6 bisphosphate

Answer

PEP to Pyruvate

Question 10

All of the following regarding Glucokinase are true except?

Accepted Answer

low Km for glucose

Answer

High Vmax for glucose

Answer

indirectly inhibited by fructose 6 phosphate and stimulated by glucose

Answer

Not inhibited by Glucose 6 phosphate

Answer

Mutation of this enzyme cause MODY 2 and also play a role in gestational diabetes

Question 11

All of the following about PFK1 are true except

Accepted Answer

none of the above

Answer

PFK 1 irreversibly commits G6P to glycolysis

Answer

PFK1 is allosterically inhibited by ATP

Answer

PFK1 is allosterically activated by AMP and fructose 2,6 bisphosphate

Question 12

Pyruvate Kinase deficiency causes hemolytic anemia

Answer

true

Question 13

All of the following are true about Warburg effect except?

Accepted Answer

Works for all body cancers including brain

Answer

Proliferating cells get ATP from glycolysis not Oxidative Phosphorylation

Answer

Glycolysis is up regulated by oncogenes

Answer

Damaged mitochondria so no TCA cycle only glycolysis

Question 14

All of the following about PDC (pyruvate dehydrogenase complex) are true except

Accepted Answer

None of the above

Answer

Co factor for E1 is B1, Cofactor for E2 is lipoic acid and cofactor for E3 is FAD/NAD

Answer

E1 is X linked

Answer

PDH deficiency causes lactic acidosis and a type of subacute necrotizing encephalomyelopathy (Leigh disease)

Question 15

Following all are the fates of pyruvate except

Accepted Answer

none of the above

Answer

Transmination becomes Alanine

Answer

Dehydrogenation becomes acetyl CoA (by PDH in the presence of Oxygen)

Answer

In the absence of oxygen becomes lactate

Answer

Carboxylation to Oxaloacetate

Question 16

PDH kinase inactivates PDC

Answer

true

Question 17

The only substrate level ATP production in TCA cycle is from succinyl CoA to succinate

Answer

true

Question 18

TCA cycle produces NADH for OxPhos, OxPhos produces ATP

Answer

true

Question 19

All of the following about ETC is correct except?

Accepted Answer

ETC reduces NADH and FADH2

Answer

Complex I cofactor is NADH

Answer

Complex II - Cofactor FADH2

Answer

CoQ only component of ETC not protein bound

Answer

Complex III - cytochrome b-c1

Question 20

All of the following statements are true except

Accepted Answer

2,4 Dinitrophenol is an uncoupling agent - which increases proton gradient

Answer

Rotenone is inhibitor of complex 1 in ETC

Answer

Inhibition of Complex 1 causes a decrease in proton gradient

Answer

Oligomycin is an ATP synthase inhibitor - which increases the proton gradient

Question 21

The primary carbon-containing molecules that are substrates for gluconeogenesis are alanine from protein degradation, lactate from anaerobic glycolysis and glycerol from fat

Answer

true

Question 22

All of the following are gluconeogenic enzymes except

Accepted Answer

None of the above

Answer

Pyruvate carboxylase

Answer

PEP carboxykinase

Answer

Fructose 1,6 bisphosphatase

Answer

Glucose 6 phosphatase

Question 23

All of the following are true about HMP shunt

Accepted Answer

all of the above

Answer

Provides a source of NADPH and ribose

Answer

Oxidative (irreversible) reaction generates NADPH

Answer

Non oxidative (reversible) reaction generated Ribose 5 phosphate

Answer

1 and 2 only

Question 24

All of the following are true about Reactive Oxygen Species

Accepted Answer

All of the above

Answer

SOD, Catalase and Glutathione are all the enzymes that are used as a defense against oxygen toxicity

Answer

OH radicle attacks the C=C polyunsaturated lipid in membrane which yields malondialdehyde

Answer

Free radical production is part of host defense, intended to destroy microorganism and tumor cells

Question 25

Acetaminphen

Accepted Answer

NAPQI cannot be metabolized

Answer

Normal amounts of which are sulphated or glucuronated for excretion

Answer

Excess is oxidized by Cyp 2E1 to toxic NAPQI

Answer

N acetyl cysteine is the treatment for acetaminophen toxicity

Question 26

Ethanol

Accepted Answer

all of the above are correct

Answer

Dehydrogenated to Acetaldehyde by ADH which is then dehydrogenated by ALDH to acetyl CoA

Answer

Pyruvate is converted to lactate to generate NAD+ which can be used in the above dehydrogenase reactions as Hydrogen acceptor

Answer

Lactic acidosis, gout, hypoglycemia and hyperlipidemia are all acute effects of ethanol metabolism

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