MCQ Practice Quiz

Question 1

Ligand-gated ion channels:

A) are located intracellularly
B) include muscarinic receptors
C) mediate cell response to growth factors
D) of the GABAa subtype conduct Cl-
E) none of the above

Answer 1

D) of the GABAa subtype conduct Cl-

Question 2

Which of the following statements about receptors in cell signalling is FALSE?
A) each cell expresses only one type of G protein.
B) oestrogen receptors are located in the nucleus of target cells.
C) a hormone or neurotransmitter receptor may be an ion channel.
D) insulin receptors have tyrosine
specific protein kinase activity.
E) phosphodiesterase inhibition increases intracellular cAMP levels.

Answer 2

A) each cell expresses only one type of G protein.

Question 3

Regarding cell signalling, all the following statements are true EXCEPT:
A) signalling by ionic channels is rapid.
B) effectors include adenylyl cyclase and phospholipase C.
C) signalling through nicotinic cholinoceptors involves G proteins.
D) signalling by steroid receptors occurs intracellularly.
E) signalling through cAMP is terminated by phosphodiesterases.

Answer 3

C) signalling through nicotinic cholinoceptors involves G proteins.

Question 4

Regarding drug receptor interaction, all the following are true EXCEPT:
A) it conforms to the Law of Mass Action.
B) it usually involves breakdown of the drug molecule.
C) it may be stereospecific.
D) it does not usually involve formation of covalent bonds.
E) potency of agonists can be measured from their dose/response curve.

Answer 4

B) it usually involves breakdown of the drug molecule.

Question 5

Regarding drug efficacy and potency, which of the following statements is FALSE?
A) efficacy is indicated by the height of the dose response curve.
B) antagonists have an efficacy=0.
C) EC50 is a measure of a drug’s potency.
D) drugs with similar pharmacologic effect can differ in efficacy.
E) agonists have higher potency than antagonists.

Answer 5

E) agonists have higher potency than antagonists.

Question 6

Antagonism of leukotriene’s bronchoconstrictor effect (mediated at leukotriene receptors) by terbutaline (acting at adrenoceptors) in a patient with asthma:
A) competitive antagonist
B) partial agonist
C) physiological antagonist
D) chemical antagonist
E) pharmacokinetic interaction

Answer 6

C) physiological antagonist

Question 7

An antagonist that interacts directly with the agonist and not at all, or only incidentally, with the receptor:
A) competitive antagonist
B) partial agonist
C) physiological antagonist
D) chemical antagonist
E) pharmacokinetic interaction

Answer 7

D) chemical antagonist

Question 8

A drug that blocks the action of adrenaline at its receptors by occupying those receptors without activating them:
A) competitive antagonist
B) partial agonist
C) physiological antagonist
D) chemical antagonist
E) pharmacokinetic interaction

Answer 8

A) competitive antagonist

Question 9

A drug such as Pindolol that raises heart rate a little but blunts its response to sympathetic stimulation or circulating adrenaline:
A) competitive antagonist
B) partial agonist
C) physiological antagonist
D) chemical antagonist
E) pharmacokinetic interaction

Answer 9

B) partial agonist

Question 10

Tubocurarine analogues used to cause muscle relaxation:
A) competitive antagonist
B) partial agonist
C) physiological antagonist
D) chemical antagonist
E) pharmacokinetic interaction

Answer 10

A) competitive antagonist

Question 11

Propranolol is a competitive antagonist of noradrenaline. When
the log dose response curve seen with both noradrenaline and propranolol is compared to that seen with noradrenaline alone, which of the following statements about the noradrenaline propranolol curve is FALSE?
A) it has the same maximum as the noradrenaline curve.
B) it is shifted to the right of the noradrenaline curve.
C) it is parallel to the noradrenaline curve.
D) it has the same EC50 as the noradrenaline curve.
E) it shows that propranolol effect is overcome at high noradrenaline concentration.

Answer 11

D) it has the same EC50 as the noradrenaline curve.

Question 12

The Two-State receptor model proposes each of the following EXCEPT:
A) activated and inactivated states represent different 3 dimensional
receptor conformations .
B) ligands with much higher affinity for receptor in its activated state will
act as full agonists.
C) ligands with higher affinity for receptor in its inactivated (resting) state will act as antagonists.
D) receptors can produce some response in the absence of ligand.
E) relative affinity for activated over inactivated receptor determines the
efficacy of a partial agonist.

Answer 12

C) ligands with higher affinity for receptor in its inactivated (resting) state will act as antagonists.

Question 13

Drug side effects may be due to:
A) actions at target receptors but outside the target tissue(s)
B) actions in the target tissue(s) but at non target receptors
C) excess dosage
D) A and B
E) A and B and C

Answer 13

E) A and B and C

Question 14

Drug tolerance may be due to any of the following EXCEPT:
A) depletion of mediators
B) physiological adaptation
C) reduced drug clearance
D) reduced number of receptors, due to internalisation and/or lower expression
E) reduced receptor response, due to modification

Answer 14

C) reduced drug clearance

Question 15

Regarding the ANS, what is the main neurotransmitter at 1?
A) acetylcholine
B) atropine
C) clonidine
D) noradrenaline
E) tubocurarine

Answer 15

A) acetylcholine

Question 16

Regarding the ANS, what is the main neurotransmitter at 2?
A) acetylcholine
B) atropine
C) clonidine
D) noradrenaline
E) tubocurarine

Answer 16

D) noradrenaline

Question 17

Regarding the ANS, what REDUCES neurotransmission at 2?
A) acetylcholine
B) atropine
C) clonidine
D) noradrenaline
E) tubocurarine

Answer 17

C) clonidine

Question 18

Regarding the ANS, what BLOCKS neurotransmission at 3?
A) acetylcholine
B) atropine
C) clonidine
D) noradrenaline
E) tubocurarine

Answer 18

B) atropine

Question 19

Regarding the ANS, what BLOCKS neurotransmission at 4?
A) acetylcholine
B) atropine
C) clonidine
D) noradrenaline
E) tubocurarine

Answer 19

E) tubocurarine

Question 20

At the cholinergic synapse:
A) choline is an important neurotransmitter.
B) acetylcholinesterase inhibition increases neurotransmission.
C) cocaine increases neurotransmission.
D) nicotine mimics acetylcholine in ANS innervated target tissues.
E) muscarine blocks ganglionic neurotransmission.

Answer 20

B) acetylcholinesterase inhibition increases neurotransmission.

Question 21

Regarding acetylcholinesterase:
A) inhibition increases adrenaline concentration in the synapse.
B) neostigmine causes neuromuscular block.
C) organophosphate insecticides reversibly inhibit the enzyme.
D) symptoms of organophosphate poisoning are defecation, urination, miosis, bronchoconstriction, emesis, lacrimation, salivation.
E) ecothiophate is a short acting inhibitor.

Answer 21

D) symptoms of organophosphate poisoning are defecation, urination, miosis, bronchoconstriction, emesis, lacrimation, salivation.

Question 22

At the adrenergic synapse:
A) neurotransmitter is synthesized by monoamine oxidase.
B) dopamine is an antagonist.
C) α2-adrenoceptor agonists enhance neurotransmitter release.
D) adrenoceptor activation causes response through intracellular second messenger(s).
E) cocaine and amphetamines reduce neurotransmission.

Answer 22

D) adrenoceptor activation causes response through intracellular second messenger(s).

Question 23

Adrenoceptors:
A) are multisubunit proteins.
B) are antagonised by catecholamines.
C) mediate cell responses to growth factors.
D) occur at the neuromuscular junction.
E) of the β1 subtype increase heart rate and contraction.

Answer 23

E) of the β1 subtype increase heart rate and contraction.

Question 24

Patient response to a drug may be affected by all of the following EXCEPT:
A) absorption from site of administration
B) clinical trial results
C) drug interactions
D) interaction with receptor
E) inter and intrapatient variation

Answer 24

B) clinical trial results

Question 25

Regarding therapeutic index of a drug, each of the following statements is true EXCEPT:
A) narrow therapeutic index leads to risk of potentially significant drug drug interactions.
B) therapeutic index = TD50 /ED 50
C) therapeutic index takes into account idiosyncratic toxicity such as hypersensitivity (allergy) to penicillins
D) therapeutic index takes into account variation between individuals.
E) C and D

Answer 25

E) C and D

Question 26

Regarding cardiac drugs:
A) lignocaine slows cardiac conduction by inhibiting Na+ channels.
B) digoxin inhibits Na+,K+ ATPase.
C) phosphodiesterase inhibitors increase contractility in failing
heart.
D) Only A & B are true.
E) All are true.

Answer 26

E) All are true.

Question 27

All these statements are
true EXCEPT:
A) drug A is about 10 fold more potent than drug B.
B) the data show that the EC50 for drug B is about 10nM.
C) one hundred nanomolar (nM) drug A may not occupy all available receptors.
D) drug A and drug B probably elicit tissue response by different mechanisms.
E) A curve almost identical to curve B could be obtained if a competitive
antagonist were present with drug A.

Answer 27

D) drug A and drug B probably elicit tissue response by different mechanisms.

Question 28

Two hundred and fifty microlitres (250 μL ) of a solution of drug X
(molecular weight 200) that contains 1 mg/mL is added to a preparation of rabbit ileum in an organ bath of volume 25 mL. X elicits no response itself but substantially reduces the tissue’s response to a subsequent addition of acetylcholine.
A) X could be tubocurarine
B) the final concentration of
X in the organ bath is 1 μg/ml.
C) the final concentration of
X in the organ bath is 2 μM.
D) X is likely to reduce response of a strip of skeletal muscle to acetylcholine.
E) All are false.

Answer 28

C) the final concentration of
X in the organ bath is 2 μM.

Question 29

Would a higher or lower pA value indicate drug has highest AFFINITY for receptor?

Answer 29

Higher

Question 30

Would a higher or lower pA value indicate a drug to be most POTENT at receptor?

Answer 30

Lower

Question 31

Would a larger or smaller pA value difference indicate a drug to be most SELECTIVE at receptor?

Answer 31

Larger

Question 32

Would a larger or smaller pA value difference indicate a drug to be most likely to cause SIDE-EFFECTS?

Answer 32

Smaller

Question 33

What part of a Dose-Response curve indicates the POTENCY of a drug?

Answer 33

EC50

Question 34

What part of a Dose-Response curve indicates the EFFICACY of a drug?

Answer 34

% max. response

Question 35

What is Carbachol?

Answer 35

Acetylcholine receptor agonist

Question 36

What is Physostigmine?

Answer 36

Acetylcholinesterase Inhibitor

Question 37

What is Tubocurarine?

Answer 37

Antagonist of nACh receptor on NMJ

Question 38

What is Atropine?

Answer 38

Antagonist at mACh receptors