All Free Biology MCQs with Answers

• A. Epilepsy
• B. Alzheimer's disease
• C. Parkinson's disease
• D. Lou Gehrig's disease

Explanation: The hallmark symptom of epilepsy is seizures, which can vary widely in their presentation. Seizures may involve convulsions (jerking movements), loss of consciousness, staring spells, unusual sensations, or changes in behavior. The type and severity of seizures can differ from person to person.

• A. High molecular weight
• B. Insoluble in water
• C. Tasteless
• D. Polymers of glucose

Explanation: The correct answer is High molecular weight. Polysaccharides are large and complex carbohydrates made up of many monosaccharide units, which gives them a high molecular weight. Option B, insoluble in water, is incorrect because some polysaccharides can dissolve in water or form colloidal solutions, depending on their structure. Option C, Tasteless, is also incorrect because not all polysaccharides are tasteless; their taste can vary depending on their specific type and structure. Option D, Polymers of glucose, is also incorrect, as not all polysaccharides are polymer of glucose.

• A. Ester
• B. Peptide
• C. Glycosidic
• D. Phosphodiester

Explanation: The correct answer is glycosidic. Amylase is an enzyme that catalyzes the breakdown of carbohydrates, specifically starch, into simpler sugars. It achieves this by cleaving glycosidic bonds, which are the links between individual sugar units in starch. Ester bonds are associated with lipids, peptide bonds with proteins, and phosphodiester bonds with nucleic acids, none of which are substrates for amylase.

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

Explanation: Chitin is the correct answer because it is a polysaccharide that contains nitrogen, specifically in its N-acetylglucosamine monomers. This makes it structurally distinct from other common polysaccharides like starch, cellulose, and glycogen, which are composed solely of glucose units and do not contain nitrogen. Chitin is found in the exoskeletons of arthropods and is a key component in the cell walls of fungi.

• A. 1,4 Glycosidic Linkage
• B. 1,2 Glycosidic Linkage
• C. 1,6 Glycosidic Linkage
• D. 1,3 Glycosidic Linkage

Explanation: In a sucrose molecule, the 1 carbon of glucose is connected to the 2 carbon of fructose, so this bond is called a 1,2 glycosidic linkage.

• A. Carbon, nitrogen, and potassium
• B. Carbon, hydrogen, and chlorine
• C. Carbon, nitrogen, and oxygen
• D. Carbon, hydrogen, and oxygen

Explanation: Carbohydrates, as the name suggests, contains the elements carbon , hydrogen and oxygen. A typical example would be glucose.

• A. Glucose (C6H12O5)
• B. Sucrose (C2H2O)
• C. Rhamnose (C6H12O5)n
• D. Lactic acid (C3H6O3)

Explanation: Lactic acid is an organic molecule. Its chemical formula is C3H6O3 Lactic acid has the same proportion of carbon, hydrogen and oxygen as carbohydrates but it is technically not a carbohydrate.

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

Explanation: When sucrose is hydrolyzed, one molecule each of α D -glucose and β D fructose.

• A. Lactose and Glucose
• B. Lactose and Fructose
• C. Glucose and fructose
• D. Glucose and galactose

Explanation: Sucrose, also known as table sugar, is a disaccharide that is hydrolyzed into two monosaccharides: glucose and fructose. This reaction is catalyzed by the enzyme sucrase:Sucrose (C12H22O11) → Glucose (C6H12O6) + Fructose (C6H12O6)

• A. Sucrose, Glucose and Fructose
• B. Maltose, Lactose and Fructose
• C. Glycogen, Sucrose and Maltose
• D. Glycogen, Cellulose and Starch

Explanation: Polysaccharides are complex long-chain carbohydrates that are formed by dehydrate synthesis or polymerization of more than 10 but generally a very large number of units called monosaccharides. Starch, glycogen, and cellulose are all polysaccharides. Starch is a glucose homopolysaccharide which is the main reserve food of plants. Glycogen is also a glucosan homopoly­saccharide which is the major reserve food of fungi, animals, and some bacteria. It is also called animal starch. Cellulose is the structural polysaccharide of plant cell walls, some fungi, protists. It is a fibrous glucosan homopolysaccharide of high tensile strength.