All Free Biology MCQs with Answers

4221. What is the most abundant carbohydrate in nature?

• A. Cellulose
• B. Starch
• C. Fructose
• D. Glycogen

Explanation: A type of carbohydrate, cellulose contains chains of glucose rings, providing strength and rigidity. Cellulose forms the cell walls of plants and is the primary constituent of wood, making this organic compound the most abundant one on the surface of the Earth.

4222. Which of the following does not yield glucose on complete hydrolysis?

• A. Starch
• B. Glycogen
• C. Cellulose
• D. Chitin

Explanation: Chitin is an Nz-containing polysaccharide and it will yield N-acetyl-D-glucosamine on hydrolysis while starch and glycogen will yield a-D glucose monomers and Cellulose will yield B-D glucose monomers on hydrolysis.

4223. Which sugar does glucose combine with to give Lactose (milk sugar) ?

• A. Glucose
• B. Fructose
• C. Galactose
• D. Mannose

Explanation: Glucose and galactose combine to give lactose-the milk sugar. Glucose and glucose give maltose, while glucose and fructose give sucrose.

4224. How many water molecules will be released upon the formation of a trisaccharide?

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: Upon the formation of a trisaccharide, two water molecules will be released.

4225. How many carbon atoms are present inside the ring of fructose?

• A. 6
• B. 4
• C. 5
• D. 3

Explanation: Four carbon atoms are present inside the ring of fructose, while two carbon atoms are present outside of the ring.

4226. Pick out the odd one:

• A. Cellulose
• B. Galactose
• C. Agar
• D. Pectin

Explanation: Cellulose, agar and pectin are examples of polysaccharides but galactose is an example of a monosaccharide.

4227. Which of the following carbons are present outside the ring of fructose?

• A. 1st carbon & 2nd carbon
• B. 1st carbon and 5th carbon
• C. Only Ist carbon
• D. 1st carbon and 6th carbon

Explanation: Fructose can form a five cornered ring structure called fructofuranose, having four carbons and an oxygen atom within the ring while the first and last carbons remain outside the ring, i.e., 1st carbon and 6th carbon.

4228. Which of the following sugar is most sweet?

• A. Glucose
• B. Sucrose
• C. Fructose
• D. Maltose

Explanation: Fructose has the ketone functional group which gives it a sweet taste when dissolved in water.

4229. If there are 12 carbon atoms in a disaccharide, how many OH groups will it have?

• A. 11
• B. 8
• C. 10
• D. 12

Explanation: Each monosaccharide has 5 OH groups. To form a disaccharide, a condensation reaction takes place-releasing a water molecule. The water molecule contains an OH from one reactant and an H from one reactant. Hence, a total of 8 OH groups are left.

4230. Which of the following is a non-reducing disaccharide sugar?

• A. Mannose
• B. Maltose
• C. Sucrose
• D. Lactose

Explanation: The reducing group in sucrose is used in the glycosidic bond formation due to which it is non-reducing in nature. On the other hand, mannose, maltose and Lactose are all reducing sugars.