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1- What is the commonest mode of absorption of fructose?

Answer- Facilitated transport through GLUT-5.

2- What is the biochemical defect is classical galactosemia?

Answer- Deficiency of Galactose- 1-P Uridyl transferase

3-In which of the pathways of glucose utilization, CO2 is not evolved?

Answer- Glycolysis

4- What is the cause of hemolysis in Pyruvate kinase deficiency?

Answer- Energy deficit, improper functioning of Na-K  ATPase pump, retention of Sodium in the cell, osmolysis.

5- What is the reason that ascorbic acid can not be synthesized by human beings whereas it can well be synthesized by plants and certain animals?

 Answer- Deficiency of gulonolactone oxidase enzyme.

6- Name the precipitating factors for causing symptoms of Glucose-6-P dehydrogenase deficiency.

Answer- Drugs (Analgesics/ Antipyretics, antibiotics and antimalarials), infections and ingestion of fava beans.

7- Which reaction is catalyzed by Aldolase B enzyme?

Answer-  It is an enzyme of fructose metabolism causes cleavage of Fructose-1-P to form glyceraldehyde and dihydroxy acetone phosphate.

8- What is the point of entry of glycerol in the pathway of gluconeogenesis?

Answer- Glycerol  is  first phosphorylated to form Glycerol-3-P, that gets converted to dihydroxy acetone phosphate to gain entry in to the pathway of gluconeogenesis.

9- What are the sources of Acetyl co A?

Answer- Acetyl co A is mainly produced from pyruvate, fatty acid oxidation, ketolysis, alcohol metabolism and from ketogenic amino acids.

10- What is the main significance of Fructose 2, 6 bisphosphate?

 Answer- It acts as a positive allosteric modifier for PFK-1 enzyme. The whole pathway is thus stimulated.

11- What is the end product of glycolysis in red blood cells?

Answer- Lactate.

12- How many ATP s are produced from one molecule of glucose upon complete oxidation in red blood cells?

Answer- 2 ATPs

13- Name the pyruvate forming amino acids.

Answer- Glycine, alanine, serine, tryptophan, threonine and cysteine.

14- What is the reason that Acetyl co A is not considered glucogenic?

Answer- Firstly the reaction from Pyruvate to Acetyl coA is irreversible, secondly in TCA cycle Acetyl co A loses both its carbons as CO2 , hence nothing is left for glucose production.

15- What is the cause of abdominal distension and diarrhea in lactose intolerance?

Answer- Undigested lactose undergoes bacterial fermentation to produce gases (a mixture of hydrogen, carbon dioxide, and methane).The osmotic load of the unabsorbed lactose causes secretion of fluid and electrolytes until osmotic equilibrium is reached. The combined increase in fecal water, intestinal transit, and generated hydrogen gas accounts for the wide range of gastrointestinal symptoms.

16- Out of Hexokinase and Glucokinase which of the enzymes has larger km?

Answer- Glucokinase has a larger km than hexokinase.

17- Name the key enzyme for glycogen degradation?

Answer- Phosphorylase.

18- What is the cause of hypoglycemia upon chronic alcohol intake?

Answer- Chronic alcohol consumption causes hypoglycemia due to-

a) Dietary deprivation

b) Depletion of glycogen stores

c) Inhibition of gluconeogenesis (Alcohol metabolism results in accumulation of NADH , the equilibrium of the reactions requiring this coenzyme is favored towards utilization of NADH, thus pyruvate and oxaloacetate are converted to lactate and malate respectively, in the deficiency of substrates, the pathway of gluconeogenesis is inhibited. )

19- Out of insulin and glucagon which of these two hormones promotes glycogenolysis?

Answer- Glucagon

20- Name the confirmatory tests for Essential Pentosuria?

Answer- Bial’s test and chromatography.

Note- Students should consult the theory notes or subjective questions for further details.

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