All Free Biology MCQs with Answers

4251. Which of the following does not yield phosphorus on hydrolysis?

• A. Nucleotide
• B. Nucleoside
• C. DNA
• D. RNA

Explanation: Nucleoside is only made up of pentose sugar and nitrogenous base.

4252. Which of the following do not contain phosphodiester bond?

• A. DNA
• B. ATP
• C. RNA
• D. NAD

Explanation: ATP is a single nucleotide. Phosphodiester bond is present between nucleotides.

4253. Water is a very good solvent for substance due to its_ nature and acts as_ due to its higher heat capacity.

• A. Dipole nature, Thermo-stabilizer
• B. Organic, Inorganic
• C. Polar, Bipolar
• D. Ionic, Covalent

Explanation: Water is an excellent solvent for polar substances due to its dipole nature. Tons and molecules move randomly and are in a more favorable state to react with other molecules and ions when in solution and water has greater ability to absorb heat due to higher heat capacity and act as thermal-stabilizer.

4254. Due to higher heat capacity and H bonds, water acts as:

• A. Thermo-stabilizer
• B. Solvent
• C. Inert medium
• D. Reactive medium

Explanation: Water has great ability to absorb heat with minimum change in its own temperature due to higher heat capacity and act as thermal-stabilizer.

4255. Coenzymes are closely related to:

• A. Hormones
• B. Inhibitors
• C. Antibodies
• D. Vitamins

Explanation: Because many of the coenzymes are derived from the vitamins, e.g. NAD is a coenzyme and is derived from vitamins.

4256. The effect of reversible competitive inhibitor can be neutralized by increasing the concentration of:

• A. Substrate
• B. Enzyme
• C. Activator
• D. Inhibitor

Explanation: Addition of more substrate molecules will replace inhibitors, and will bind with the active site of the enzyme and results in an increase in rate of reaction.

4257. Which of the following gives blue color with iodine?

• A. Starch
• B. Cellulose
• C. Glycogen
• D. All of these

Explanation: Cellulose gives no color with iodine. Glycogen gives red color with iodine while starch gives blue color with iodine.

4258. Which bond is the potential source of chemical energy for cellular activities?

• A. C-N
• B. C-O
• C. C-H
• D. H-O

Explanation: Carbon-oxygen association in glycosidic linkages provides stability to the complex carbohydrate molecules, Carbon combines with nitrogen in amino acid linkages to form peptide bonds and forms proteins. Affinity of hydrogen for high electronegative oxygen is responsible for hydrogen bonding.

4259. Which of the following components is less resistant to decay?

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

Explanation: Starch is an example of functional carbohydrate and it is less resistant to decay because it can be easily digested in the human body. Lignin, chitin and cellulose are examples of structural polysaccharides and show more resistance to decay.

4260. Haemoglobin exhibits:

• A. Secondary Structure
• B. Primary Structure
• C. Quaternary Structure
• D. Tertiary Structure

Explanation: Haemoglobin consists of four polypeptide chains and exhibits quaternary structure.