Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
Last updated
1,790 questions · page 66 of 90
- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The carboxylate ion, which is the conjugate base of a carboxylic acid, can be represented by two resonance structures.
Correct answer: Option C- A. Ethanoic acid
- B. Ethanol
- C. Phenol
- D. Water
Explanation: Ethanol is correct because ethanol is less acidic compared to the other options listed.
Correct answer: Ethanol- A. Alkanoyl chloride
- B. Alkyl alkanoate
- C. Alkane amides
- D. Alkanal
Explanation: Unlike the other options, alkanals are not derivatives of carboxylic acids.
Correct answer: Alkanal- A. Ester
- B. Carboxylic acid
- C. Ketone
- D. Aldehydes
Explanation: Esters are commonly used as artificial flavorings in jams. As mentioned earlier, esters have a pleasant fruity aroma and taste, making…
Correct answer: Ester- A. R - NH2
- B. R- COCI
- C. RCOOH
- D. RCH2 -- OH
Explanation: Carboxylic acids readily react with bases like NaOH to form salts (carboxylate salts) and water through acid-base neutralization reactions.
Correct answer: RCOOH- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Explanation for this question will be added soon!
Correct answer: Option D- A. Methanoic acid
- B. Ethanoic acid
- C. Propanoic acid
- D. Butanoic acid
Explanation: Ethanoic acid is indeed prepared by the acid hydrolysis of ethane nitrile (acetonitrile).
Correct answer: Ethanoic acid- A. 2, 4-Dimethylpentanoic acid
- B. 4, 2-Dimethylpentanoic acid
- C. 2, 3-Dimethylpentanoic acid
- D. 4, 3-Dimethylpentanoic acid
Explanation: Option A is correct because it accurately describes the positions of the two methyl groups on the pentanoic acid chain.
Correct answer: 2, 4-Dimethylpentanoic acid- A. Ethanamide
- B. Ethanenitrile
- C. Ethylamine
- D. Nitromethane
Explanation: This is the correct product of the reaction between ethanoic acid and ammonia.
Correct answer: Ethanamide- A. Acid amide
- B. Acid halide
- C. Ester
- D. Acid anhydrid
Explanation: The most reactive derivative of carboxylic acid among the options provided is acid halide.
Correct answer: Acid halide- A. Reaction with H2
- B. Reaction with NH3
- C. Hydrolysis
- D. Reaction With alcohol
Explanation: When an acid chloride reacts with hydrogen gas (H2) in the presence of a suitable catalyst, such as palladium or platinum, it undergoes…
Correct answer: Reaction with H2- A. Acid halide
- B. Acid amide
- C. Ester
- D. Acid anhydride
Explanation: Acid amides are the least reactive among the given derivatives of carboxylic acids.
Correct answer: Acid amide- A. Aliphatic
- B. Carboxylic
- C. Alicyclic
- D. Aromatic
Explanation: When -COOH (carboxyl group) is attached directly to the benzene ring, it forms benzoic acid, which is an example of an aromatic compound.
Correct answer: Aromatic- A. CH3COOCH3
- B. HCOOCH3
- C. CH3COOC2H5
- D. CH3COOH
Explanation: In first step, hydration of alkynes occur that produces acetaldehyde. In next step, oxidation of acetaldehyde produces acetic acid.
Correct answer: CH3COOCH31315. Which of the following reagents helps us to distinguish between methanoic acid and ethanoic acid?
- A. Litmus solution
- B. Tolien's reagent
- C. Alcoholic AgNO3
- D. Sod. bicarbonate
Explanation: The correct reagent that helps distinguish between methanoic acid and ethanoic acid is B) Tolien's reagent (Fehling's solution B).
Correct answer: Tolien's reagent1316. The sequence of the amino acids combined in a peptide chain is referred to as the_ of protein:
- A. Primary structure
- B. Secondary structure
- C. Tertiary structure
- D. Quaternary structure
Explanation: The correct term used to refer to the sequence of amino acids in a peptide chain that makes up the protein is A) Primary structure.
Correct answer: Primary structure- A. Primary structure
- B. Secondary structure
- C. Tertiary structure
- D. Quaternary structure
Explanation: The correct term used to describe the regular coiling or zigzagging of polypeptide chains caused by hydrogen bonding between NH and C=O…
Correct answer: Secondary structure- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The mismatched cofactor and enzyme pair is D) Vitamin B1 (Thiamine) with glucosephosphatase.
Correct answer: Option D- A. Collagen
- B. Oligopeptides
- C. Lipoprotein
- D. Laetoglobulin
Explanation: Lipoproteins are examples of derived proteins. They are complexes of proteins and lipids (fats) that transport lipids through the…
Correct answer: Lipoprotein- A. Co-factor
- B. Prosthetic group
- C. Isoenzyme
- D. Substrate
Explanation: The specific substance (metabolite) that fits on the enzyme surface and is converted to products is called substrate.
Correct answer: Substrate