All Free Biology MCQs with Answers

4491. Non-toxic vitamins include which of the following?

• A. Vitamin C
• B. Vitamin B
• C. Both A and B
• D. None of the above

Explanation: Vitamin B is important for our body because it keeps our hair eyes and skin healthy while vitamin C boosts collagen synthesis and immune function, making both not toxic and therefore option C is correct.

4492. Which of the following statement is not correct?

• A. A peptide bond is CO-NH
• B. Each polypeptide has one C terminal and the other N terminal
• C. The amino acid sequence of a protein determines the function of the protein
• D. The union of two amino acids produces two peptide linkages

Explanation: A peptide linkage is an amide linkage. It is represented by -CONH-. Thus, option A is correct. Each polypeptide has one C terminal with carboxylic group and one N terminal with amino group. Thus, option B is correct. The function of the protein depends on the sequence of the amino acids. Thus, option C is correct. The union of two amino acids produces one peptide linkages.Thus, the option D is incorrect.

4493. The two polypeptides of human insulin are linked together by:

• A. Covalent bonds
• B. Disulphide bridges
• C. Hydrogen bonds
• D. Phosphodiester bonds

Explanation: Human insulin is made up of 51 amino acids arranged in two polypeptide chains. one alpha and one beta chain. The alpha chain contains 21 amino acids while the beta chain contains 30 amino acids. The two polypeptide chains are interconnected by disulfide bridges or S-­S linkages.

4494. Maximum number of ATP is obtained from:

• A. Glucose
• B. Palmitic acid
• C. Malic acid
• D. β-amino acid

Explanation: Palmitic acid is a saturated fatty acid that belongs to the long-chain fatty acids family. It is one of the most common saturated fatty acids found in animals, plants, and microorganisms. The chemical formula of palmitic acid is C₁₆H₃₂O₂, and its systematic name is hexadecanoic acid.

4495. Which one is dollar of the cell?

• A. ATP
• B. DNA
• C. Chromosome
• D. Enzyme

Explanation: The energy currency of the cell is known as ATP, therefore option A is correct.

4496. _is a macromolecule found in blood.

• A. Hemoglobin
• B. Plasma
• C. Creatinine
• D. Plasmids

Explanation: "The explanation for this question will be added soon!".

4497. Collagen is a:

• A. Fibrous protein
• B. Globular protein
• C. Lipid
• D. Carbohydrate

Explanation: Collagen is an insoluble fibrous protein found extensively in the connective tissue of skin, tendons and bone. Collagen accounts for over 30% of the total body protein of mammals. Globular proteins have compact rounded molecules and are usually water-soluble. Lipids are a diverse group of organic compounds, that are insoluble in water but soluble in organic solvents. Carbohydrates are compounds of carbon, hydrogen and oxygen.

4498. Choose the correct statement:

• A. The human body does not produce Enzymes
• B. The human body does not produce Vitamins
• C. Proteins are energy source for our body
• D. Nucleic acids are building blocks for our body

Explanation: Vitamins are organic compounds which have to be obtained from the diet, either because an organism does not have the enzymes necessary to synthesize them or because it cannot produce them in sufficient quantities.

4499. Why are triacylglycerols used in the human body for energy storage?

• A. They are highly hydrated and therefore can store lots of energy
• B. They always have short fatty acid chains for easy access by metabolic enzymes
• C. The carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation
• D. Polysaccharides, which would actually be a better energy storage form, would dissolve in the body

Explanation: The correct answer is C: The carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation. Triacylglycerols, or triglycerides, serve as the primary form of energy storage in the human body due to several factors:High Energy Density: The fatty acid chains in triglycerides contain carbon atoms that are highly reduced, meaning they are bonded to a larger number of hydrogen atoms. This structure allows triglycerides to release a significant amount of energy during oxidation, making them more energy-dense than carbohydrates or proteins.Efficient Storage: Being hydrophobic, triglycerides can be stored in an anhydrous form within adipose tissues, which optimizes space and energy storage compared to carbohydrates that are more hydrated.Prolonged Energy Release: Triglycerides can be broken down over time into glycerol and fatty acids, providing a sustained energy supply through metabolic processes like lipolysis and beta-oxidation, ideal for prolonged energy needs.In contrast, the other options are incorrect because:Option A incorrectly states that triacylglycerols are highly hydrated, which is not true; their hydrophobic nature actually aids in energy storage.Option B misrepresents the nature of fatty acid chains, as they can vary in length and not all are short-chain.Option D inaccurately suggests that polysaccharides would be a better energy storage form, ignoring the efficiency and density benefits of triglycerides.

4500. Which of the following statements is true regarding saturated fatty acids?

• A. They contain double bonds between carbon atoms
• B. They have a higher melting point compared to unsaturated fatty acids
• C. They are commonly found in plant oils
• D. They contribute to increased levels of 'good' cholesterol (HDL) in the body

Explanation: Saturated fatty acids have a higher melting point compared to unsaturated fatty acids. The absence of double bonds in saturated fatty acids allows for tighter packing between the fatty acid chains. This results in stronger intermolecular forces, leading to a more solid structure at room temperature and a higher melting point.