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Dr.Niraj Mahajan
Dr.Niraj Mahajan
Dr.Niraj Mahajan


Biochemistry MCQ

By AdminPosted On 05-Oct-2016

1. Enzyme Deficiency : Biochemistry MCQ

What is the most common enzyme deficiency?

a) Pyruvate kinase deficiency.

b) 21-Hydroxylase.

c) Glucose-6-phosphate dehydrogenase deficiency.

d) 5-alpha-reductase deficiency.

Correct Answer: c) G6PD deficiency is the most common human enzyme defect, being present in more than 400 million people worldwide. G6PD deficiency resulted in 4,100 deaths in 2013.

2. Gout : Biochemistry MCQ

A patient was diagnosed to have gout, which of the following enzymes could be targeted by allopurinol for the treatment of this patient?

a) Guanase

b) Hypoxanthine guanine phosphpribosyl transferase

c) Nuleotidase

d) Phosphoribosylpyrophosphate synthase

e) Xanthine oxidase

Correct Answer: e) Xanthine oxidase. Allopurinol is a drug used primarily to treat hyperuricemia and its complications, including chronic gout. Allopurinol is a purine analog; it is a structural isomer of hypoxanthine (a naturally occurring purine in the body) and is an inhibitor of the enzyme xanthine oxidase. Xanthine oxidase is responsible for the successive oxidation of hypoxanthine and xanthine, resulting in the production of uric acid, the product of human purine metabolism.

3. Osmosis : Biochemistry MCQ

The process in which water moves through a selectively permeable membrane in the direction of higher solute concentration is called

a) diffusion.

b) facilitated diffusion.

c) osmosis.

d) active transport.

e) filtration.

Correct Answer: c) osmosis. Facilitated diffusion is the diffusion of substances from one side of the membrane to the other through special channel proteins in the membrane.

4. Catabolism of Carbohydrate : Biochemistry MCQ

The first set of reactions that occurs during the catabolism of carbohydrates in cells is called

a) the Kreb's cycle.

b) the electron transport system.

c) glycolysis.

d) tricarboxylic acid cycle.

e) the oxidative phosphorylation.

Correct Answer: c) Glycolysis. Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+. The free energy released in this process is used to form the high-energy compounds ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide).

5. Jeans Fabric : Biochemistry MCQ

Newly made blue jeans are stiff because of the large amounts of starch used in the fabric. The starch is added to make the fabric easier to cut and sew. However, it also makes the material difficult to wear comfortably. Some microbiologists came up with a way of using microbial enzymes to remove the starch before the blue jeans are sold. Which of the following enzymes would be effective at removing the starch?

a) lipase

b) cellulase

c) amylase

d) protease

e) lactase

Correct Answer: c) Amylase. It is an enzyme that catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Amylase solutions are applied to the denim and break down the starch-based size, allowing fabrics to be dyed. Lipase, cellulose, protease and lactase does not break down starch.

6. Carbohydrates : Biochemistry MCQ

Monosaccharides, disaccharides, and polysaccharides belong to what group of organic molecules?

a) proteins

b) carbohydrates

c) lipids

d) nucleic acids

e) fats

Correct Answer: b) carbohydrates. There are three classes of carbohydrates: monosaccharides, disaccharides, and polysaccharides. The substance most people refer to as "sugar" is the disaccharide sucrose, which is extracted from either sugar cane or beets. Sucrose is the sweetest of the disaccharides. The polysaccharide that animals use for the short-term storage of food energy is known as glycogen. The most abundant structural polysaccharide is cellulose. There is so much cellulose in the cell walls of plants that it is the most abundant of all biological molecules. Most animals cannot digest cellulose because they don't have an enzyme that can cleave b-linkages between glucose molecules. Cellulose in their diet therefore serves only as fiber, or roughage. The digestive tracts of some animals, such as cows, horses, sheep, and goats contain bacteria that have enzymes that cleave these b-linkages, so these animals can digest cellulose.

7. Starvation : Biochemistry MCQ

Which ketone bodies can be used as an energy supply for the brain in starvation?

a) Acetyl CoA

b) Acetone

c) Acetoacetate

d) Choline

e) Succinate

Correct Answer: c) Acetoacetate. Acetone is also a ketone body but is not used for energy. It is excreted in urine and is also exhaled in the breath.

8. Catabolism and Anabolism : Biochemistry MCQ

Metabolic pathways in which large, energy-rich molecules are broken down into smaller, lower energy products are called

a) ergonomics.

b) anabolism.

c) catabolism.

d) exergonic.

e) entropy.

Correct Answer: c) Catabolism. Endocrinologists have traditionally classified many of the hormones as anabolic or catabolic, depending on which part of metabolism they stimulate. The so-called classic catabolic hormones are cortisol, glucagon, and adrenaline (and other catecholamines). Anabolism involves the building of larger molecules from smaller ones. Exergonic refers to energy given off by a chemical reaction. Entropy refers to the energy within a system.

9. Protein Denaturation : Biochemistry MCQ

If a protein is excessively heated, its shape can permanently change and the protein will no longer carry out its function. This process is called

a) hydrolysis.

b) thermal catabolism.

c) denaturation.

d) ionization.

e) dehydrogenation.

Correct Answer: c) Denaturation. When food is cooked, some of its proteins become denatured. This is why boiled eggs become hard and cooked meat becomes firm.

A classic example of denaturing in proteins comes from egg whites, which are typically largely egg albumins in water. Fresh from the eggs, egg whites are transparent and liquid. Cooking the thermally unstable whites turns them opaque, forming an interconnected solid mass.

Hydrolysis is a chemical reaction in which a molecule is broken down as water is added.

Dehydrogenation is an oxidation reaction in which both an electron and an accompanying proton are removed.

10. Kidney Stone : Biochemistry MCQ

Which of the following chemical in the urine prevent the stone formations?

a) Sodium

b) Citrate

c) Glucose

d) Vitamine C

e) ketone bodies

Correct Answer: b) Citrate is a molecule that binds to calcium in the urine, preventing calcium from binding to oxalate or phosphate and forming a stone. Citrus drinks like lemonade and orange juice protect against kidney stones because they contain citrate, which stops crystals from growing into stones. Animal protein raise the risk of calcium stones by increasing the excretion of calcium and reducing the excretion of citrate into the urine. Citrate prevents kidney stones, but the acid in animal protein reduces the citrate in urine.

11. Pyruvate as Energy : Biochemistry MCQ

Which biochemical process creates pyruvate as an energy supply?

a) Beta oxidation

b) Glycolysis

c) Gluconeogenesis

d) Oxidative deamination

e) The citric acid cycle

Correct Answer: b) Glycolysis. Glycolysis converts monosaccharides into pyruvate before conversion to acetyl coenzyme A. This then fuels the citric acid cycle. It is particularly helpful because it does not require oxygen. Gluconeogenesis is metabolic pathway resulting in generation of glucose from non-carbohydrate substrates such as lactates,glycerol and aminoacids. Beta oxidation involves fatty acid breakdown in mitochondria to generate acyl CoA.

12. Amount of Protein : Biochemistry MCQ

Which biochemical technique is used to detect the presence and the amount of a protein?

a) Northern blotting

b) Polymerase chain reaction

c) Southern blotting

d) Western blotting

e) X-ray crystalography

Correct Answer: d) Western blotting. Southern blotting is used to detect particular sequences to DNA. Northern blotting is used for the same reason but for RNA. Polymerase chain reaction is used to amplify very small amounts of DNA (although it can be used for RNA if converted to DNA). X-ray crystallography is used to reveal the structure of nucleic acids such as DNA and RNA.

13. Which of the following food has highest protein content?

a) Chicken / Turkey breast

b) Prawns

c) Permesan cheese

d) Beef

e) Whole Chicken egg

f) Dry roasted Soya bean

g) Roasted peanut

h) Fish (Tuna/ Salmon)

Correct Answer: c and d. Permesan cheese and Beef.

Protein content in foods, given in measurements of grams of protein per 100 grams of food portion ....

a) Chicken / Turkey breast - 30 gm

b) Prawns - 17.0 gm

c) Permesan cheese - 40.79 gm

d) Beef - 40.6 gm

e) Whole Chicken egg - 13.63 gm

f) Dry roasted Soya bean - 39.58 gm

g) Roasted peanut - 28.04 gm

h) Fish (Tuna/ Salmon) - 26 gm

14. Growth Hormone : Biochemistry MCQ

Which hormone has a structure similar to growth hormone?

a) Anti-müllerian hormone

b) Cortisol

c) Follicle-stimulating hormone

d) Insulin

e) Prolactin

Correct Answer: e) Prolactin. Growth hormone is structurally similar to prolactin and human placental lactogen.

15. RNA : Biochemistry MCQ

Which of the following amino acid bases is not contained in RNA?

a) Adenine

b) Cytosine

c) Guanine

d) Thymine

e) Uracil

Correct Answer: d) Thymine. In RNA the thymine is replaced by uracil. The other bases (adenine, cystosine and guanine) remain the same.

16. The following are essential amino acids

a) Arginine

b) Proline

c) Glycine

d) Valine

e) Histidine

Correct Answer: a,d,e. An essential amino acid is an amino acid that cannot be synthesized de novo, and therefore must be supplied in its diet. The amino acids regarded as essential for humans are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. Additionally, cysteine, tyrosine, and arginine are required by infants and growing children. Essential amino acids are "essential" not because they are more important for protein synthesis or general homeostasis than the others, but because the body does not synthesize them. If they are not uptaken through diet, they will not be available for protein synthesis. In addition, the amino acids arginine, cysteine, glycine, glutamine, proline, serine and tyrosine are considered conditionally essential, meaning they are not normally required in the diet, but must be supplied exogenously to specific populations that do not synthesize them in adequate amounts.

17. Iron : Biochemistry MCQ

a) Haemoglobin comprises less than 15% of total body iron

b) Aggregates of transferrin form haemisiderin

c) The total iron body content of the adult female is about 38 mg/kg

d) Iron is best absorbed in the ferrous form

e) Haem iron is more effectively absorbed than non-haem iron

Correct Answer: c,d,e. 1) Haemoglobin iron comprises about 70% of the total body iron and is the largest iron containing compartment. 2) Aggregates of ferritin form haemisiderin and not transferrin.

18. Bile Salts in Pregnancy : Biochemistry MCQ

What is the physiological mechanism for bile salts in pregnancy?

a) Aids the absorption of essential amino acids

b) Aids the absorption of fats

c) Helps to conjugate bilirubin

d) Helps to conjugate biliverdin

e) No known physiological function

Correct Answer: b) Aids the absorption of fats.

Primary bile acids are synthesized in the liver where they are conjugated to form water-soluble bile salts and excreted in the bile. Bile acids play an important role in the digestion and absorption of fat in the intestine. They are readily re-absorbed, passing through the portal system to the liver where they are re-excreted.

19. Urea and electrolytes : Biochemistry MCQ

A healthy 34-year-old woman had a total abdominal hysterectomy for cervical disease. Routine urea and electrolytes are measured one day after surgery and are as follows:

Sodium 121 (reference range 135–145 mmol/l) Potassium 4.3 (reference range 3.5–5.0 mmol/l) Urea 2.8 (reference range 2.5–6.7 mmol/l) Creatinine 74 (reference range 70–150 micromol/l)

What is the most likely cause to explain the blood test results?

a) Excessive intravenous dextrose

b) Nephrogenic diabetes insipidus

c) Primary aldosteronism

d) Undiagnosed diabetes mellitus

e) Ureteric damage

Correct Answer: a) Excessive intravenous dextrose. Hypernatraemia is common after excess IV normal saline but hyponatraemia can occur with excessive 5% dextrose IV.

20. All are true about brown fat cells EXCEPT

a) Are increased with sympathetic new fibers.

b) Contain multiple droplet of fat .

c) Are not a major site of fat storage in the fetus.

d) When stimulated they enhance best production through shivering.

Correct Answer: a and d are False statements. Sympathetic nervous system with its activation, functions as the stimulator of brown fat cells thermogenesis. In contrast to white fat cells, which contain a single lipid droplet, brown adipocytes contain numerous smaller droplets and a much higher number of (iron-containing) mitochondria, which make it brown. It is more profuse in the fetus and neonate, in whom it constitutes approximately 5% of body weight. It is involved in nonshivering thermogenesis when the body temperature falls below a threshold value.

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MD- Gynecologist, Laparoscopic Surgeon, Uro-gynecologist , Infertility specialist & Cosmetic Gynecologist.

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