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 can be controlled by giving a lowphenylalanine diet (D) It leads to decreased synthesis of thyroid hormones, catecholamines and melanin

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 can be controlled by giving a lowphenylalanine diet (D) It leads to decreased synthesis of thyroid hormones, catecholamines and melanin
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Answer : D
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All the following are true about phenylketonuria except (A) Deficiency of phenylalanine hydroxylase (B) Mental retardation (C) Increased urinary excretion of p-hydroxyphenyl pyruvic acid (D) Decrease serotonin formation

Description : All the following are true about phenylketonuria except (A) Deficiency of phenylalanine hydroxylase (B) Mental retardation (C) Increased urinary excretion of p-hydroxyphenyl pyruvic acid (D) Decrease serotonin formation

Last Answer : Answer : C

DOPA is an intermediate in the synthesis of (A) Thyroid hormones (B) Catecholamines (C) Melanin (D) Catecholamines and melanin

Description : DOPA is an intermediate in the synthesis of (A) Thyroid hormones (B) Catecholamines (C) Melanin (D) Catecholamines and melanin

Last Answer : Answer : D

Catecholamine hormones are (A) 3, 4-Dihydroxy derivatives of phenylethylamine (B) p-Hydroxy derivatives of phenylacetate (C) p-Hydroxy derivatives of phenylpyruvate (D) p-Hydroxy derivatives of phenyllactate

Description : Catecholamine hormones are (A) 3, 4-Dihydroxy derivatives of phenylethylamine (B) p-Hydroxy derivatives of phenylacetate (C) p-Hydroxy derivatives of phenylpyruvate (D) p-Hydroxy derivatives of phenyllactate

Last Answer : Answer : A

A characteristic of pheochromocytoma is elevated urinary excretion of (A) Dopamine (B) Tyrosine (C) Vinylmandelic acid (D) Phenylalanine

Description : A characteristic of pheochromocytoma is elevated urinary excretion of (A) Dopamine (B) Tyrosine (C) Vinylmandelic acid (D) Phenylalanine

Last Answer : Answer : C

Thyroid hormones are synthesized by the iodination of the amino acid: (A) Glycine (B) Phenylalanine (C) Alanine (D) Tyrosine

Description : Thyroid hormones are synthesized by the iodination of the amino acid: (A) Glycine (B) Phenylalanine (C) Alanine (D) Tyrosine

Last Answer : Answer : D

Tyrosine hydroxylase is inhibited by (A) Catecholamines (B) α−Methyldopa (C) Phenylalanine (D) Vanillyl mandelic acid

Description : Tyrosine hydroxylase is inhibited by (A) Catecholamines (B) α−Methyldopa (C) Phenylalanine (D) Vanillyl mandelic acid

Last Answer : Answer : A

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 : 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

Last Answer : Answer : C

All of the following statements about primary gout are true except (A) Uric acid stones may be formed in kidneys (B) Arthritis of small joints occurs commonly (C) Urinary excretion of uric acid is decreased (D) It occurs predominantly in males

Description : All of the following statements about primary gout are true except (A) Uric acid stones may be formed in kidneys (B) Arthritis of small joints occurs commonly (C) Urinary excretion of uric acid is decreased (D) It occurs predominantly in males

Last Answer : Answer : C

All of the following occur in orotic aciduria except (A) Increased synthesis of pyrimidine nucleotides (B) Increased excretion of orotic acid in urine (C) Decreased synthesis of cytidine triphosphate (D) Retardation of growth

Description : All of the following occur in orotic aciduria except (A) Increased synthesis of pyrimidine nucleotides (B) Increased excretion of orotic acid in urine (C) Decreased synthesis of cytidine triphosphate (D) Retardation of growth

Last Answer : Answer : A

In case of wilson’s disease, the features include all of the following except (A) Progressive hepatic cirrhosis (B) Keyser Fleisher ring (C) Aminoaciduria (D) Urinary excretion of Cu is decreased

Description : In case of wilson’s disease, the features include all of the following except (A) Progressive hepatic cirrhosis (B) Keyser Fleisher ring (C) Aminoaciduria (D) Urinary excretion of Cu is decreased

Last Answer : Answer : D

Tryptophan could be considered as precursor of (A) Melanotonin (B) Thyroid hormones (C) Melanin (D) Epinephrine

Description : Tryptophan could be considered as precursor of (A) Melanotonin (B) Thyroid hormones (C) Melanin (D) Epinephrine

Last Answer : Answer : A

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 : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase

Last Answer : Answer : B

Hormones thyroxine, adrenaline and the pigment melanin are formed from (a) tyrosine (b) proline (c) tryptophan (d) glycine.

Description : Hormones thyroxine, adrenaline and the pigment melanin are formed from (a) tyrosine (b) proline (c) tryptophan (d) glycine.

Last Answer : (a) tyrosine

Increased urinary indole acetic acid is diagnostic of (A) Maple syrup urine disease (B) Hartnup disease (C) Homocystinuia (D) Phenylketonuria

Description : Increased urinary indole acetic acid is diagnostic of (A) Maple syrup urine disease (B) Hartnup disease (C) Homocystinuia (D) Phenylketonuria

Last Answer : Answer : B

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

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

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

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

All of the following statements about allopurinol are true except (A) It is a structural analogue of uric acid (B) It can prevent uric acid stones in the kidneys (C) It increases the urinary excretion of xanthine and hypoxanthine (D) It is a competitive inhibitor of xanthine oxidase

Description : All of the following statements about allopurinol are true except (A) It is a structural analogue of uric acid (B) It can prevent uric acid stones in the kidneys (C) It increases the urinary excretion of xanthine and hypoxanthine (D) It is a competitive inhibitor of xanthine oxidase

Last Answer : Answer : A

During compensation of respiratory alkalosis, all the following changes occur except (A) Decreased secretion of hydrogen ions by renal tubules (B) Increased excretion of sodium in urine (C) Increased excretion of bicarbonate in urine (D) Increased excretion of ammonia in urine

Description : During compensation of respiratory alkalosis, all the following changes occur except (A) Decreased secretion of hydrogen ions by renal tubules (B) Increased excretion of sodium in urine (C) Increased excretion of bicarbonate in urine (D) Increased excretion of ammonia in urine

Last Answer : Answer : D

Absence of phenylalanine hydroxylase causes (A) Neonatal tyrosinemia (B) Phenylketonuria (C) Primary hyperoxaluria (D) Albinism

Description : Absence of phenylalanine hydroxylase causes (A) Neonatal tyrosinemia (B) Phenylketonuria (C) Primary hyperoxaluria (D) Albinism

Last Answer : Answer : D

An amino acid used for the synthesis of thyroid hormone is (A) Tyrosine (B) Tryptophan (C) Histidine (D) Proline

Description : An amino acid used for the synthesis of thyroid hormone is (A) Tyrosine (B) Tryptophan (C) Histidine (D) Proline

Last Answer : Answer : A

Which of the following statements regarding hypercalcemia are true? A. The symptoms of hypercalcemia may mimic some symptoms of hyperglycemia. B. Metastatic breast cancer is an unusual cause of hypercalcemia. C. Calcitonin is a satisfactory long-term therapy for hypercalcemia. D. Severely hypercalcemic patients exhibit the signs of extracellular fluid volume deficit. E. Urinary calcium excretion may be increased by vigorous volume repletion.

Description : Which of the following statements regarding hypercalcemia are true? A. The symptoms of hypercalcemia may mimic some symptoms of hyperglycemia. B. Metastatic breast cancer is an unusual cause of ... fluid volume deficit. E. Urinary calcium excretion may be increased by vigorous volume repletion.

Last Answer : Answer: ADE DISCUSSION: Markedly elevated serum calcium levels produce polydipsia, polyuria, and thirst. Vigorous volume repletion and saline diuresis correct the extracellular fluid volume ... , from bony metastasis. The calcitonin effect on calcium is diminished with repeat administrations

All the following statements about endemic goiter are true except (A) It occurs in areas where soil and water have low iodine content (B) It leads to enlargement of thyroid gland (C) It results ultimately in hyperthyroidism (D) It can be prevented by consumption of iodised salt

Description : All the following statements about endemic goiter are true except (A) It occurs in areas where soil and water have low iodine content (B) It leads to enlargement of thyroid gland (C) It results ultimately in hyperthyroidism (D) It can be prevented by consumption of iodised salt

Last Answer : Answer : C

Increased urinary excretion of orotic acid can occur in deficiency of (A) Orotate phosphoribosyl transferase (B) OMP decarboxylase (C) Mitochondrial ornithine transcarbamoylase (D) Any of the above

Description : Increased urinary excretion of orotic acid can occur in deficiency of (A) Orotate phosphoribosyl transferase (B) OMP decarboxylase (C) Mitochondrial ornithine transcarbamoylase (D) Any of the above

Last Answer : Answer : D

Urinary excretion of vanillyl madelic acid is increased in (A) Phaeochromocytoma (B) Cushing’s syndrome (C) Carcinoid syndrome (D) Aldosteronism

Description : Urinary excretion of vanillyl madelic acid is increased in (A) Phaeochromocytoma (B) Cushing’s syndrome (C) Carcinoid syndrome (D) Aldosteronism

Last Answer : Answer : A

Pentosuria is a rare hereditary disease is characterized by increased urinary excretion of (A) L-xylulose (B) Xylitol (C) Xylulose 5-phosphate (D) Ribose 5-phosphate

Description : Pentosuria is a rare hereditary disease is characterized by increased urinary excretion of (A) L-xylulose (B) Xylitol (C) Xylulose 5-phosphate (D) Ribose 5-phosphate

Last Answer : Answer : A

Folic acid deficiency can be diagnosed by increased urinary excretion of (A) Methylmalonate (B) Figlu (C) Cystathionine (D) Creatinine

Description : Folic acid deficiency can be diagnosed by increased urinary excretion of (A) Methylmalonate (B) Figlu (C) Cystathionine (D) Creatinine

Last Answer : Answer : B

Formation of melanin from tyrosine requires the action of (A) Dopa decarboxylation (B) Diamine oxidase (C) Peroxidase (D) Tyrosinase

Description : Formation of melanin from tyrosine requires the action of (A) Dopa decarboxylation (B) Diamine oxidase (C) Peroxidase (D) Tyrosinase

Last Answer : Answer : D

Melatonin is synthesised from (A) Phenylalanine (B) Tyrosine (C) Tryptophan (D) None of these

Description : Melatonin is synthesised from (A) Phenylalanine (B) Tyrosine (C) Tryptophan (D) None of these

Last Answer : Answer : C

For Catecholamine biosynthesis the rate limiting enzyme is (A) DOPA decarboxylase (B) DOPAMINE β-hydroxylase (C) Tyrosine hydroxylase (D) Phenylalanine hydroxylase

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

Neonatal tyrosinemia is due to deficiency of the enzyme: (A) p-Hydroxyphenylpyruvate hydroxylase (B) Fumarylacetoacetate hydrolase (C) Phenylalanine hydroxylase (D) Tyrosine dehydrogenase

Description : Neonatal tyrosinemia is due to deficiency of the enzyme: (A) p-Hydroxyphenylpyruvate hydroxylase (B) Fumarylacetoacetate hydrolase (C) Phenylalanine hydroxylase (D) Tyrosine dehydrogenase

Last Answer : Answer : B

Albinism is due to deficiency of the enzyme: (A) Phenylalanine hydroxylase (B) Tyrosinase (C) p-Hydroxyphenylpyruvic acid oxidase (D) Tyrosine dehydrogenase

Description : Albinism is due to deficiency of the enzyme: (A) Phenylalanine hydroxylase (B) Tyrosinase (C) p-Hydroxyphenylpyruvic acid oxidase (D) Tyrosine dehydrogenase

Last Answer : Answer : C

Activation or inactivation of certain key regulatory enzymes is accomplished by covalent modification of the amino acid: (A) Tyrosine (B) Phenylalanine (C) Lysine (D) Serine

Description : Activation or inactivation of certain key regulatory enzymes is accomplished by covalent modification of the amino acid: (A) Tyrosine (B) Phenylalanine (C) Lysine (D) Serine

Last Answer : Answer : D

Niacin can be synthesised in human beings from (A) Histidine (B) Phenylalanine (C) Tyrosine (D) Tryptophan

Description : Niacin can be synthesised in human beings from (A) Histidine (B) Phenylalanine (C) Tyrosine (D) Tryptophan

Last Answer : Answer : D

Richner-Hanhart syndrome is due to defect in (A) Tyrosinase (B) Phenylalanine hydroxylase (C) Hepatic tyrosine transaminase (D) Fumarylacetoacetate hydrolase

Description : Richner-Hanhart syndrome is due to defect in (A) Tyrosinase (B) Phenylalanine hydroxylase (C) Hepatic tyrosine transaminase (D) Fumarylacetoacetate hydrolase

Last Answer : Answer : B

Million’s test is positive for (A) Phenylalanine (B) Glycine (C) Tyrosine (D) Proline

Description : Million’s test is positive for (A) Phenylalanine (B) Glycine (C) Tyrosine (D) Proline

Last Answer : Answer : C

Which one of the following is an essential amino acid? (A) Arginine (B) Tyrosine (C) Phenylalanine (D) Proline

Description : Which one of the following is an essential amino acid? (A) Arginine (B) Tyrosine (C) Phenylalanine (D) Proline

Last Answer : Answer : C

Serotonin is synthesised from (A) Serine (B) Phenylalanine (C) Tyrosine (D) Tryptophan

Description : Serotonin is synthesised from (A) Serine (B) Phenylalanine (C) Tyrosine (D) Tryptophan

Last Answer : Answer : D

The limiting amino acid of rice is (A) Lysine (B) Tryptophan (C) Phenylalanine (D) Tyrosine

Description : The limiting amino acid of rice is (A) Lysine (B) Tryptophan (C) Phenylalanine (D) Tyrosine

Last Answer : Answer : A

Million-Nasse’s reaction is specific for the amino acid: (A) Tryptophan (B) Tyrosine (C) Phenylalanine (D) Arginine

Description : Million-Nasse’s reaction is specific for the amino acid: (A) Tryptophan (B) Tyrosine (C) Phenylalanine (D) Arginine

Last Answer : Answer : B

Phenylalanine is the precursor of (A) L-DOPA (B) Histamine (C) Tyrosine (D) Throxine

Description : Phenylalanine is the precursor of (A) L-DOPA (B) Histamine (C) Tyrosine (D) Throxine

Last Answer : C

An enzyme required for the synthesis of thyroid hormones is (A) Iodinase (B) Deiodinase (C) Thyroperoxidase (D) Thyroxine synthetase

Description : An enzyme required for the synthesis of thyroid hormones is (A) Iodinase (B) Deiodinase (C) Thyroperoxidase (D) Thyroxine synthetase

Last Answer : Answer : C

Tyrosine is required for the synthesis of all of the following except (A) Melatonin (B) Epinephrine (C) Norepinephrine (D) Thyroxine 222 MCQs IN BIOCHEMISTRY

Description : Tyrosine is required for the synthesis of all of the following except (A) Melatonin (B) Epinephrine (C) Norepinephrine (D) Thyroxine 222 MCQs IN BIOCHEMISTRY

Last Answer : Answer : A

An important finding in Histidinemia is (A) Impairment of conversion of α-Glutamate to α-ketoglutarate (B) Speech defect (C) Decreased urinary histidine level (D) Patients can not be treated by diet

Description : An important finding in Histidinemia is (A) Impairment of conversion of α-Glutamate to α-ketoglutarate (B) Speech defect (C) Decreased urinary histidine level (D) Patients can not be treated by diet

Last Answer : Answer : B

Which one of the following statements concerning glucose metabolism is correct? (A) The conversion of Glucose to lactate occurs only in the R.B.C (B) Glucose enters most cells by a mechanism in which Na+ and glucose are co-transported (C) Pyruvate kinase catalyses an irreversible reaction (D) An elevated level of insulin leads to a decreased level of fructose 2, 6-bisphosphate in hepatocyte

Description : Which one of the following statements concerning glucose metabolism is correct? (A) The conversion of Glucose to lactate occurs only in the R.B.C (B) Glucose enters most cells by a mechanism in ... ) An elevated level of insulin leads to a decreased level of fructose 2, 6-bisphosphate in hepatocyte

Last Answer : C

Figure shows human urinary system with structures labelled A to D. Select option which correctly identifies them and gives their characteristic and/ or functions. (a) C - Medulla - inner zone of kidney and contains complete nephrons. (b) D - Cortex - outer part of kidney and do not contain any part of nephrons. (c) A - Adrenal gland - located at the anterior part of kidney. Secrete catecholamines which stimulate glycogen breakdown. (d) B - Pelvis - broad funnel shaped space inner to hilum, directly connected to loops of Henle

Description : Figure shows human urinary system with structures labelled A to D. Select option which correctly identifies them and gives their characteristic and/ or functions. (a) C - Medulla - inner zone of ... B - Pelvis - broad funnel shaped space inner to hilum, directly connected to loops of Henle

Last Answer : (c) A - Adrenal gland - located at the anterior part of kidney. Secrete catecholamines which stimulate glycogen breakdown.

All the following statements about albinism are correct except (A) Tyrosine hydroxylase (tyrosinase) is absent or deficient in melanocytes (B) Skin is hypopigmented (C) It results in mental retardation (D) Eyes are hypopigmented

Description : All the following statements about albinism are correct except (A) Tyrosine hydroxylase (tyrosinase) is absent or deficient in melanocytes (B) Skin is hypopigmented (C) It results in mental retardation (D) Eyes are hypopigmented

Last Answer : Answer : C

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

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

Small amount of urinary oxalates is contributed by the amino acid: (A) Glycine (B) Tyrosine (C) Alanine (D) Serine

Description : Small amount of urinary oxalates is contributed by the amino acid: (A) Glycine (B) Tyrosine (C) Alanine (D) Serine

Last Answer : Answer : A

.Khorana first deciphered the triplet codons of (a) serine and isoleucine (b) cysteine and valine (c) tyrosine and tryptophan (d) phenylalanine and methinonine.

Description : .Khorana first deciphered the triplet codons of (a) serine and isoleucine (b) cysteine and valine (c) tyrosine and tryptophan (d) phenylalanine and methinonine.

Last Answer : (a) serine and isoleucine

Khorana first deciphered the triplet codons of (a) serine and isoleucine (b) cysteine and valine (c) tyrosine and tryptophan (d) phenylalanine and methinonine

Description : Khorana first deciphered the triplet codons of (a) serine and isoleucine (b) cysteine and valine (c) tyrosine and tryptophan (d) phenylalanine and methinonine

Last Answer : (b) cysteine and valine