Exams › NEET › Chemistry › Biomolecules
100 questions with worked solutions.
Q1. Among the following organic acids, the acid present in rancid butter is:
Answer: butyric acid
Butyric acid is a short-chain fatty acid responsible for the unpleasant smell of rancid butter due to its breakdown in fats.
Answer: I and III
Polysaccharides are generally amorphous and only sparingly soluble in water, so statement I is correct and II is correct. They are not sugars; they are carbohydrate polymers made of many monosaccharide units, so III is incorrect.
Q3. Which of the following has been used in the manufacture of non-inflammable photographic films?
Answer: Cellulose acetate
Cellulose acetate is much less flammable than cellulose nitrate, so it was adopted for safety photographic films. The other listed derivatives are not the standard material used for non-inflammable film bases.
Q4. Incorrect statement about given carbohydrate is
Answer: Above compound is a reducing sugar
The correct statement is that the compound is a reducing sugar because it has a free anomeric carbon capable of opening to the aldehyde/ketone form. That same free anomeric center also allows mutarotation, so the claim that it is non-reducing is the incorrect one.
Answer: Propionaldehyde cyanohydrin
Hydrolysis of a cyanohydrin gives an α-hydroxy acid. Propionaldehyde cyanohydrin yields lactic acid, which is chiral and has the CH3CH(OH)COOH framework; its corresponding oxidation state includes the CH3CO– motif required for iodoform positivity. The other options either give achiral products or acids that do not satisfy both conditions together.
Q6. Which of the following is a polysaccharide?
Answer: Cellulose
Cellulose is a polysaccharide because it consists of many glucose units linked together into long chains. Sucrose and maltose are disaccharides, while galactose is a monosaccharide.
Q7. Which of the following is a pentose sugar?
Answer: Ribose
Ribose is a pentose, meaning it contains five carbon atoms. Glucose and fructose are hexoses, while cellulose is a polysaccharide, not a single sugar.
Q8. To prevent food from spoilage by microorganism, which substance is used?
Answer: Salt of sorbic acid
Salt of sorbic acid is a preservative used in foods to prevent spoilage by microorganisms, especially molds and yeasts. The other options are not primarily used for antimicrobial preservation.
Q9. The drug cimetidine was designed to: This question has multiple correct options
Answer: prevent the interaction of histamine with receptors
Cimetidine is an H2-receptor antagonist, so it prevents histamine from binding to its receptors. That reduces gastric acid secretion; it does not stimulate pepsin, and “all of the above” is incorrect.
Q10. Mg is present in
Answer: Chlorophy
Magnesium is the central atom in chlorophyll, the green pigment used by plants to capture light for photosynthesis. The other options are associated with different elements or structures, not magnesium.
Q11. Which of the following acts as a biological catalyst?
Answer: Proteins
Proteins act as biological catalysts because enzymes are proteins that lower activation energy and speed up reactions without being consumed. Lipids and carbohydrates mainly serve storage or structural roles, and nucleic acids store/transmit genetic information.
Q12. In nucleic acids, the sequence is:
Answer: sugar-base-phosphate
In nucleic acids, each nucleotide has a sugar linked to a phosphate group and a nitrogenous base. The chain is organized with the sugar-phosphate backbone, while the base is attached to the sugar, giving the sequence sugar-base-phosphate in the nucleotide structure.
Q13. Reducing sugar can reduce:
Answer: Fehling solution to cuprous oxide
Reducing sugars have a free anomeric carbon that can act as a reducing agent. In Fehling’s solution, they reduce blue Cu2+ ions to red cuprous oxide (Cu2O).
Q14. Which component present in human hair?
Answer: Keratin
Human hair is primarily made of keratin, a strong fibrous structural protein. The other options are not the main material of hair: cellulose is in plants, myoglobin is in muscle, and albumin is a blood protein.
Q15. Sucrose on hydrolysis gives?
Answer: Glucose+Fructose
Sucrose is composed of one glucose unit and one fructose unit linked by a glycosidic bond. On hydrolysis, that bond is cleaved to give the two monosaccharides.
Q16. The term vitamin was introduced by
Answer: Dr. Funk
Dr. Casimir Funk introduced the term “vitamin” while studying substances essential for preventing deficiency diseases. He derived it from “vital amine,” which later became shortened to vitamin.
Q17. Which of the following are used as an antacid to reduce acidity in stomach?
Answer: Sodium bicarbonate and magnesium hydroxide
Sodium bicarbonate and magnesium hydroxide are both weak bases used to neutralize excess hydrochloric acid in the stomach. Strong bases like sodium hydroxide or calcium hydroxide are too corrosive to be used as antacids.
Q18. Dalda (Vanaspathi) is prepared by:
Answer: hydrogenation of triolien
Dalda (vanaspati) is made by hydrogenating an unsaturated oil, which turns liquid triglycerides into a more saturated, semi-solid fat. Triolein is an unsaturated triglyceride, so its hydrogenation gives vanaspati.
Answer: Antiseptic
Phenol at 1% is dilute enough to be used on living tissue, so it acts as an antiseptic. Disinfectants are generally used at higher concentrations on inanimate objects.
Q20. Which of the following is true about alpha amino acids?
Answer: Both of the above
In Fischer projections of alpha amino acids, the amino group on the left corresponds to the L-series, while on the right corresponds to the D-series. Both statements describe this convention correctly.