Description : In the biosynthesis of testosterone the rate limiting step is conversion of (A) Cholesterol to pregnenolone (B) Pregnenolone to progesterone (C) Progesterone to 17 α-hydroxy progesterone (D) 17 α-Hydroxy progesterone to androstenedione
Last Answer : Answer : A
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 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
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 : What is the rate-limiting-step in the cholesterol biosynthesis?
Last Answer : HMG CoA reductase.
Description : The rage limiting step cholesterol biosynthesis is (A) Squalene synthetase (B) Mevalonate kinase (C) HMG CoA synthetase (D) HMG CoA reductase
Last Answer : Answer : D
Description : The rate limiting step in cholesterol biosynthesis is one of the followings : (A) LDL-receptor concentration (B) VLDL secretion (C) Mevalonic acid formation (D) Co-enzyme A formation
Last Answer : (C) Mevalonic acid formation
Description : Cholesterol is the precursor for the biosynthesis of (A) fatty acid (B) prostaglandins (C) bile acids (D) sphingmyelin
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 : The biosynthesis of both Catecholamine and serotonin require (A) Tyrosine hydroxylase (B) N-methyl transferase (C) Aromatic amino acid decarboxylase (D) Tryptophan pyrrolase
Description : In the biosynthesis of cortiol, the sequence of enzymes involved is (A) Hydroxylase–dehydrogenase + isomerase – hydroxylase (B) Dehydrogenase–hydroxylase–isomerase (C) Hydroxylase–lyase–dehydrogenase isomerase (D) Isomerase–lyase–hydroxylase–dehydrogenase
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 : The rate limiting reaction in the lipogenic pathway is (A) Acetyl-CoA carboxylase step (B) Ketoacyl synthase step (C) Ketoacyl reductase step (D) Hydratase step
Description : All the following statements about obstructive jaundice are true except (A) Prothrombin time may be prolonged due to impaired absorption of vitamin K (B) Serum alkaline phosphatase may be raised ... systemic circulation due to biliary obstruction (D) There is no defect in conjugation of bilirubin
Description : Lack of Glucocorticoids and mineral corticoids might be consequence of which of the following defects in the adrenal cortex? (A) Androstenadione deficiency (B) Estrone deficiency (C) 17 α-OH progesterone deficiency (D) C- α-Hydroxylase deficiency
Description : The defect in adrenal cortex responsible for lack of glucocorticoids and mineralcorticoids is (A) Androstenedione deficiency (B) 17 α -OH progesterone deficiency (C) C-21 hydroxylase deficiency (D) Testosterone deficiency HORMONE METABOLISM 209
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
Description : In the biosynthesis of cholesterol, the step which controls the rate and locus of metabolic regulation is (A) Geranyl pyrophosphate farnesyl pyrophosphate (B) Squalene → lanosterol (C) HMG CoA → mevalonate (D) Lanosterol → 1, 4-desmethyl lanosterol
Description : In the biosynthesis of the iron protoporphyrin, the product of the condensation between succinyl-CoA and glycine is (A) α-Amino β-ketoadipic acid (B) δ-Aminolevulinate (C) Hydroxymethylbilane (D) Uroporphyrinogen I
Description : What is the rate-limiting-step in ketone body formation?
Last Answer : HMGCoA synthase.
Description : A key substance in the committed step of pyrimidines biosynthesis is (A) Ribose-5-phosphate (B) Carbamoyl phosphate (C) ATP (D) Glutamine
Description : The ‘Committed step’ in the biosynthesis of cholesterol from acetyl CoA is (A) Formation of acetoacetyl CoA from acetyl CoA (B) Formation of mevalonate from HMG CoA (C) Formation of HMG CoA from acetyl CoA and acetoacetyl CoA (D) Formation of squalene by squalene synthetase
Description : Urea biosynthesis occurs mainly in the liver involving the number of amino acids: (A) 3 (B) 4 (C) 5 (D) 6
Description : For biosynthesis of proteins (A) Amino acids only are required (B) Amino acids and nucleic acids only are required (C) Amino acid, nucleic acids and ATP only are required (D) Amino acids, nucleic acids, ATP, GTP, enzymes and activators are required
Description : The reaction catalysed by phosphofructokinase (A) Is activated by high concentrations of ATP and citrate (B) Uses fruitose-1-phosphate as substrate (C) Is the rate-limiting reaction of the glycolytic pathway (D) Is inhibited by fructose 2, 6-bisphosphate
Last Answer : C
Description : The amino acids present in pulses can supplement the limiting amino acids of (A) Cereals (B) Milk (C) Fish (D) Nuts and beans
Description : Choose the correct statement about lovastatin: A. It markedly lowers plasma triglyceride with little effect on cholesterol level B. It is used as an adjuvant to gemfibrozil for type III ... hypercholesterolemia D. It is a competitive inhibitor of the rate limiting step in cholesterol synthesis
Last Answer : D. It is a competitive inhibitor of the rate limiting step in cholesterol synthesis
Description : Which of one ring in the structure of the following is aromatic? (A) Androgens (B) Estrogens (C) Cholesterol (D) Bile acids
Description : Hypolipidemic drugs reduce serum cholesterol and triacylglycerol. The effect of clofibrate is attributed to (A) Block in absorption from G.I.T. (B) Decrease in secretion of triacylglycerol and cholesterol ... by liver (C) Block in the reabsorption of bile acids (D) Decreased synthesis of cholesterol
Description : Vitamin C is required for the synthesis of (A) Bile acids from cholesterol (B) Bile salts from bile acids (C) Vitamin D from cholesterol (D) All of these
Description : Ascorbic acid is required to synthesise all of the following except (A) Collagen (B) Bile acids (C) Bile pigments (D) Epinephrine
Description : A compound normally used to conjugate bile acids is (A) Serine (B) Glycine (C) Glucoronic acid (D) Fatty acid
Description : Current concepts concerning the intestinal absorption of triacylglycerols are that (A) They must be completely hydrolysed before the constituent fatty acids can be absorbed (B) They are hydrolysed partially ... portal blood (D) In the absence of bile the hydrolysis of triacyl glycerols is absorbed
Description : In human and other ureotelic organisms, the end product of amino acid nitrogen metabolism: (A) Bile acids (B) Ketone bodies (C) Urea (D) Barium sulphate
Description : The basic amino acids are (A) Lysine (B) Bile acids (C) Glycine (D) Alanine
Description : The surface tension in intestinal lumen between fat droplets and aqueous medium is decreased by (A) Bile Salts (B) Bile acids (C) Conc. H2SO4 (D) Acetic acid
Last Answer : A
Description : Bile acids are derived from what substance?
Last Answer : Cholesterol.
Description : What is the function of bile acids?
Last Answer : They are the major route of excretion of cholesterol and they are required for absorption of triacyl glycerol.
Description : The pathway of glycogen biosynthesis involves a special nucleotide of glucose. In the reaction below, NuDP stands for NuDP Glucose + glycogenn → NuDP + glycogenn+1 (A) ADP (B) GDP (C) UDP (D) CDP
Description : The major determinant of the overall rate of denovo purine nucleotide biosynthesis is the concentration of (A) 5-phosphoribosyl 1-pyrophosphate (B) 5-phospho β-D-ribosylamine (C) Glycinamide ribosyl-5-phosphate (D) Formylglycinamide ribosyl-5-phosphate
Description : In mammalian liver the rate controlling enzyme in porphyrin biosynthesis is (A) ALA synthase (B) ALA hydratase (C) Uroporphyrinogen I synthase (D) Uroporphyrinogen III cosynthase
Description : The initial step of the citric acid cycle is (A) Conversion of pyruvate to acetyl-CoA (B) Condensation of acetyl-CoA with oxaloacetate (C) Conversion of citrate to isocitrate (D) Formation of α -ketoglutarate catalysed by isocitrate dehydrogenase
Description : Which of the following reactions is suitable for the preparation of α-amino acids? (a) Schmidt reaction (b) Hofmann's degradation of amides (c) Strecker's synthesis (b) Reduction of nitro compounds
Last Answer : Strecker's synthesis
Description : The principal nitrogenous excretory compound in humans is synthesised (a) in kidneys but eliminated mostly through liver (b) in kidneys as well as eliminated by kidneys (c) in liver and also eliminated by the same through bile (d) in the liver, but eliminated mostly through kidneys.
Last Answer : (d) in the liver, but eliminated mostly through kidneys.
Description : In purine biosynthesis carbon atoms at 4 and 5 position and N at 7 position are contributed by (A) Glycine (B) Glutamine (C) Alanine (D) Threonine
Description : A metabolite which is common to pathways of cholesterol biosynthesis from acetyl-CoA and cholecalciferol formation from cholesterol is (A) Zymosterol (B) Lumisterol (C) Ergosterol (D) 7 Dehydrocholesterol
Description : Which of the following gives a positive Ninhydrin test? (A) Reducing sugar (B) Triglycerides (C) α-amino acids (D) Phospholipids
Description : Thyroid stimulating hormone is a dimer. The α-subunits of TSH, LH, FSH are identical. Thus the biological specificity must therefore be β subunit in which the number of amino acids is (A) 78 (B) 112 (C) 130 (D) 199
Description : Decarboxylation of α-keto acids requires (A) Thiamine pyrophosphate, FAD, NAD+ (B) Flavin mononucleotide (C) NADP+ (D) NAD+ only