Description : The rate limiting enzyme in the synthesis of catecholamines is: A. Tyrosine hydroxylase B. Dopa decarboxylase C. Dopamine β-hydroxylase D. Noradrenaline N-methyl transferase
Last Answer : A. Tyrosine hydroxylase
Description : In the synthetic pathway of epinephrine, disulfiram (antabuse) inhibits the enzyme: (A) Tyrosine hydroxylase (B) Dopamine β-hydroxylase (C) DOPA decarboxylase (D) N-methyl transferase
Last Answer : Answer : B
Description : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase
Description : For Catecholamine biosynthesis the rate limiting enzyme is (A) DOPA decarboxylase (B) DOPAMINE β-hydroxylase (C) Tyrosine hydroxylase (D) Phenylalanine hydroxylase
Last Answer : Answer : C
Description : The following enzymes on the left are responsible for the synthesis of the neurotransmitters on the right: a. monoamine oxidase: noradrenaline b. cholinesterase: acetylcholine c. catechol-o-methyl transferase: dopamine d. dopa decarboxylase: adrenaline
Last Answer : dopa decarboxylase: adrenaline
Description : The biosynthesis of both Catecholamine and serotonin require (A) Tyrosine hydroxylase (B) N-methyl transferase (C) Aromatic amino acid decarboxylase (D) Tryptophan pyrrolase
Description : Methyldopa lowers BP by: A. Inhibiting dopa decarboxylase in adrenergic nerve endings B. Generating α-methyl noradrenaline in brain which reduces sympathetic tone C. Generating α-methyl ... as a false transmitter in peripheral adrenergic nerve endings D. Activating vascular dopamine receptors
Last Answer : B. Generating α-methyl noradrenaline in brain which reduces sympathetic tone
Description : The rate limiting step in the biosynthesis of catecholamines is (A) Decarboxylation of dihydroxyphenylalanine (B) Hydroxylation of phenylalanine (C) Hydroxylation of tyrosine (D) Oxidation of dopamine
Description : An enzyme involved in catabolism of catecholamines is (A) Dopa decarboxylase (B) Aromatic amino acid decarboxylase (C) Monoamine oxidase (D) Catechol oxidas
Description : The most efficacious inhibitor of catecholamine synthesis in the body is: A. α-methyl-p-tyrosine B. α-methyldopa C. α-methyl-norepinephrine D. Entacapone
Last Answer : A. α-methyl-p-tyrosine
Description : A sympathomimetic amine that acts almost exclusively by releasing noradrenaline from the nerve endings is: A. Ephedrine B. Dopamine C. Isoprenaline D. Tyramine
Last Answer : D. Tyramine
Description : Methyl dopa decreases blood pressure by (A) Inhibiting the synthesis of catecholamines (B) Antagonising the action of aldosterone (C) Stimulating the release of renin (D) Inhibiting the breakdown of angiotensin
Last Answer : Answer : A
Description : An inborn error, maple syrup urine disease is due to deficiency of the enzyme: (A) Isovaleryl-CoAhydrogenase (B) Phenylalnine hydroxylase (C) Adenosyl transferase (D) α-Ketoacid decarboxylase
Last Answer : Answer : D
Description : The following sympathomimetic amine has agonistic action on α 1 + α 2 + β 1 + β 3 adrenoceptors, but not on β 2 receptors: A. Adrenaline B. Noradrenaline C. Isoprenaline D. Phenylephrine
Last Answer : B. Noradrenaline
Description : Dobutamine differs from dopamine in that: A. It does not activate peripheral dopaminergic receptors B. It does not activate adrenergic β receptors C. It causes pronounced tachycardia D. It has good blood-brain barrier penetrability
Last Answer : A. It does not activate peripheral dopaminergic receptors
Description : Choose the drug which is used as a short-term inotropic in severe congestive heart failure and has selective adrenergic β 1 agonistic activity but no dopaminergic agonistic activity: A. Dopamine B. Dobutamine C. Amrinone D. Salmeterol
Last Answer : B. Dobutamine
Description : Dopaminergic D1 and D2 as well as adrenergic α and β 1, but not β 2 receptors are activated by: A. Dopamine B. Dobutamine C. Methoxamine D. Phenylephrine
Last Answer : A. Dopamine
Description : Tyrosine hydroxylase is inhibited by (A) Catecholamines (B) α−Methyldopa (C) Phenylalanine (D) Vanillyl mandelic acid
Description : Following events occur in the cytoplasm and not inside storage vesicles, except (a) Conversion of tyrosine to dopa (b) Conversion of dopa to dopamine (c) Conversion of dopamine to norepinephrine (d) Conversion of dopamine to 3,4 dihydroxy phenyl acetic acid
Last Answer : Ans: C
Description : DOPA is an intermediate in the synthesis of (A) Thyroid hormones (B) Catecholamines (C) Melanin (D) Catecholamines and melanin
Description : Sildenafil is contraindicated in patients taking the following class of drugs: A. α-adrenergic blockers B. β-adrenergic blockers C. Organic nitrates D. Angiotensin converting enzyme inhibitors
Last Answer : C. Organic nitrates
Description : The following are true about the neurotransmitters: a. acetylcholine is inactivated mainly by presynaptic reuptake b. tyrosine is essential for the formation of dopamine c. noradrenaline is inactivated mainly by hydrolysis d. adrenaline is formed from methylation of the noradrenaline
Last Answer : adrenaline is formed from methylation of the noradrenaline
Description : True statements about the following neurotransmitters include: a. dopamine is formed from tyrosine b. in the synapse, noradrenaline is inactivated by active reuptake into the presynpatic terminals c. noradrenaline is formed by hydroxylation of dopamine d. all above
Last Answer : all above
Description : Noradrenaline is administered by: A. Subcutaneous injection B. Intramuscular injection C. Slow intravenous infusion D. All of the above routes
Last Answer : C. Slow intravenous infusion
Description : The following sympathomimetic amine has agonistic action on α1 + α2 + β1 + β3 adrenoceptors, but not on β2 receptors: A. Adrenaline B. Noradrenaline C. Isoprenaline D. Phenylephrine
Description : The principal process which terminates the action of noradrenaline released from adrenergic nerve ending is: A. Degradation by MAO B. Methylation by COMT C. Axonal uptake D. Extraneuronal uptake
Last Answer : C. Axonal uptake
Description : The following type/types of noradrenaline uptake is blocked by reserpine: A. Axonal uptake B. Granular uptake C. Extraneuronal uptake D. All of the above
Last Answer : B. Granular uptake
Description : Tyramine induces release of noradrenaline from adrenergic nerve endings: A. By depolarizing the axonal membrane B. By mobilizing Ca2+ C. By a nonexocytotic process D. Only in the presence of MAO inhibitors
Last Answer : C. By a nonexocytotic process
Description : The anticholinesterase action of edrophonium is short lasting because termination of its action depends on: A. Dissociation and diffusion of the drug from the enzyme B. Hydrolysis of the drug by the enzyme C. Synthesis of fresh enzyme molecules D. A combination of the above three processes
Last Answer : A. Dissociation and diffusion of the drug from the enzyme
Description : β-Carotene, precursor of vitamin A, is oxidatively cleaved by (A) β-Carotene dioxygenase (B) Oxygenase (C) Hydroxylase (D) Transferase
Description : β-Carotene, precursor of vitamin A, is oxidatively cleaved by (A) β-Carotene dioxygenase (B) Oxygenase \ (C) Hydroxylase (D) Transferase
Last Answer : (A) β-Carotene dioxygenase
Description : Choose the drug which is used as a short-term inotropic in severe congestive heart failure and has selective adrenergic β1 agonistic activity but no dopaminergic agonistic activity: A. Dopamine B. Dobutamine C. Amrinone D. Salmeterol
Description : Dopaminergic D1 and D2 as well as adrenergic α and β1, but not β2 receptors are activated by: A. Dopamine B. Dobutamine C. Methoxamine D. Phenylephrine
Description : Select the β-adrenergic blocker that has additional α1 blocking, vasodilator and antioxidant properties: A. Carvedilol B. Celiprolol C. Acebutolol D. Metoprolol
Last Answer : C. Acebutolol
Description : In hyperthyroidism, β adrenergic blockers are used: A. To induce euthyroid state B. As definitive therapy C. For rapid control of certain symptoms while awaiting response to carbimazole D. To reduce basal metabolic rate
Last Answer : C. For rapid control of certain symptoms while awaiting response to carbimazole
Description : Biotin is a coenzyme of the enzyme (A) Carboxylase (B) Hydroxylase (C) Decarboxylase (D) Deaminase
Description : Vitamin K is involved in posttranslational modification of the blood clotting factors by acting as cofactor for the enzyme: (A) Carboxylase (B) Decarboxylase (C) Hydroxylase (D) Oxidase
Last Answer : (A) Carboxylase
Description : Vitamin K is involved in posttranslational modification of the blood clotting factors by acting as cofactor for the enzyme (A) Carboxylase (B) Decarboxylase (C) Hydroxylase (D) Oxidase
Description : All the following statements about phenylketonuria are correct except (A) Phenylalanine cannot be converted into tyrosine (B) Urinary excretion of phenylpyruvate and phenyllactate is increased (C) It ... diet (D) It leads to decreased synthesis of thyroid hormones, catecholamines and melanin
Description : Orotic aciduria type II reflects the deficiency of the enzyme: (A) Orotate phosphoribosyl transferase (B) Orotidylate decarboxylase (C) Dihydroorotase (D) Dihydroorotate dehydrogenase
Description : In the biosynthesis of cholesterol, the rate limiting enzyme is (A) Mevalonate kinase (B) HMG-CoA synthetase (C) HMG-CoA reductase (D) Cis-prenyl transferase
Description : A deficiency of copper effects the formation of normal collagen by reducing the activity of which of the following enzyme? (A) Prolyl hydroxylase (B) Lysyl oxidase (C) Lysyl hydroxylase (D) Glucosyl transferase
Description : Selenium is a constituent of the enzyme: (A) Glutathione peroxidase (B) Homogentisate oxidase (C) Tyrosine hydroxylase (D) Phenylalanin hydroxylase
Description : The deficiency of copper decreases the activity of the enzyme: (A) Lysine oxidase (B) Lysine hydroxylase (C) Tyrosine oxidase (D) Proline hydroxylase
Description : Neonatal tyrosinemia is due to deficiency of the enzyme: (A) p-Hydroxyphenylpyruvate hydroxylase (B) Fumarylacetoacetate hydrolase (C) Phenylalanine hydroxylase (D) Tyrosine dehydrogenase