All Free Biology MCQs with Answers

• A. Alpha helix
• B. Beta helix
• C. Spiral
• D. Concentrate

Explanation: Left handed helix in protein secondary structure is known as alpha helix. A type of helical structure with a left-handed twist is called beta helix. It is different from the given statement, hence, this option is incorrect. Spiral is a term used to describe any coiled or helical structure. As it is a general term, this option is incorrect. The term 'concentrate' is not related to proteins, hence, this option is incorrect. Only option A relates to the given statement so it is correct.

• A. Dehydration reaction
• B. Formation of disulphide bridges
• C. Ionic bonding of monomers
• D. Hydrolysis

Explanation: Monomers polymerize to form long chains called polymers. They undergo condensation reactions in which there may be loss of a water molecule (dehydration) or any other small molecule, or addition reactions that involve breaking of double bonds (as in the case of polymerization of ethene to form polythene).Amino acids and monosaccharides polymerize through dehydration synthesis to form polypeptides and polysaccharides respectively.

• A. Polyacrylonitrile
• B. Rayon fibre
• C. PVC
• D. Teflon

Explanation: Acrylonitrile monomers join to form polyacrylonitrile (PAN), which is also called polyvinyl cyanide or Creslan 61. It has the formula (C3H3N)n. It is a synthetic resin and is used in the manufacture of carbon fibres, clothing and furnishings.

• A. Monomers
• B. Epimers
• C. Enantiomers
• D. Isomers

Explanation: Polymers are large molecules made up of small, repeated units called monomers. Examples include polyvinyl chloride, polyester, cellulose, and glycogen.

• A. 5
• B. 4
• C. 2
• D. 3

Explanation: There are three types of polymers based on their sources:1) Natural e.g. proteins, cellulose, starch.2) Synthetic e.g. polyvinyl chloride, polyester.3) Semi-synthetic polymers e.g. cellulose nitrates, cellulose acetate.

• A. 4
• B. 2
• C. 6
• D. 3

Explanation: There are two types of polymerization reactions: 1) Condensation; formation of larger molecules from smaller ones by releasing a small molecule like water. 2) Addition; formation of larger molecules from smaller units called monomers without by-product formation.

• A. Two
• B. One
• C. Three
• D. Four

Explanation: Polymerization reactions are of two types; condensation and addition polymerization. Condensation polymerization involves combination of two monomers with loss of a group, such as water or ammonia. Addition polymerization involves breaking of double bonds as two monomers combine, eg. the polymerization of ethene to form polyethene.

• A. Cosmetic industry
• B. Fabric industry
• C. None of these
• D. Food industry

Explanation: Polyester is a synthetic fabric made from petroleum. It is one of the most popular textiles.Polyesters are most commonly made by condensation reactions between alcohols and carboxylic acids. The repeating units of polyester are linked by ester linkages.

• A. Covalent
• B. Ionic
• C. Hydrogen
• D. Metallic

Explanation: Proteins primarily contain covalent bonds which form their primary structure but they also mostly have hydrogen bonding which forms their secondary structures.

• A. Thrombin
• B. L-asparaginase
• C. Both
• D. None of these

Explanation: L-asparaginase is an enzyme used to fight anti-cancer cells in children. Thrombin is merely a clotting factor.