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.
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1,790 questions · page 53 of 90
- A. Hydrogen bond
- B. Ester linkage
- C. Covalent bond
- D. Ionic Bond
Explanation: The correct answer is ester linkage. Phosphoric acid can react with the hydroxyl (OH) group of a pentose sugar to form an ester linkage…
Correct answer: Ester linkage- A. Fatty acids
- B. Acylglycerols
- C. Phospholipids
- D. Both B and C
Explanation: Glycerol is a crucial component in the structure of both acylglycerols and phospholipids.
Correct answer: Both B and C1043. Fatty acids contain:
- A. Alcohol and esters
- B. Carboxylic group and isoprenoid
- C. Carboxylic and alkyl groups
- D. Phospholipids and alkyl groups
Explanation: The correct answer is Option C: aromatic and alkyl group. Fatty acids are characterized by a carboxyl group (COOH) at one end and an alkyl…
Correct answer: Carboxylic and alkyl groups- A. Water loving, Water fearing
- B. Soluble in water, Soluble in lipid
- C. Polar, Non-polar
- D. All are correct
Explanation: Hydrophilic substances have a strong affinity for water due to their polar nature, while hydrophobic substances repel water due to their…
Correct answer: All are correct1045. Lipids have great functional significance in the body. What are the main functions of the lipids?
- A. Energy storage and source
- B. Mechanical protection and insulation
- C. Structural component of cell membranes
- D. All of these
Explanation: The correct answer is all of these. Lipids are versatile biological molecules that perform several key functions in the body.
Correct answer: All of these1046. Waterproof surfaces like the cuticle of a leaf and the protective covering of an insect's body are:
- A. Phospholipids
- B. Waxes
- C. Terpenoids
- D. Acylglycerols
Explanation: The correct answer is waxes. Waxes serve as a protective coating because they are hydrophobic, making surfaces waterproof.
Correct answer: Waxes- A. Phospholipids
- B. Phosphatidic acid
- C. Terpenoids
- D. Waxes
Explanation: Choline is an essential nutrient that is often incorporated into phospholipids, specifically phosphatidylcholine, which is a critical…
Correct answer: Phospholipids1048. Steroids are natural:
- A. Lipoproteins
- B. Proteins
- C. Lipids
- D. All of these
Explanation: Steroids are classified as lipids because they are hydrophobic and insoluble in water, with a structure based on four fused carbon rings.
Correct answer: Lipids- A. Sugar
- B. Waxes
- C. Starches
- D. Steroids
Explanation: Steroids are a suitable example of terpenoids, as they are derived from terpenoid precursors and share a similar biosynthetic origin.
Correct answer: Steroids- A. An even number of carbon atoms
- B. Protect plants from water loss
- C. Have long-chain alkanes
- D. Water barrier substance
Explanation: The correct answer is to have long-chain alkanes. Waxes are not characterized by having long-chain alkanes.
Correct answer: Have long-chain alkanes- A. Carbohydrates
- B. Proteins
- C. Lipids
- D. None of these
Explanation: The correct answer is lipids because they are not considered true polymers.
Correct answer: Lipids1052. Phospholipids contain:
- A. Hydrophilic heads and hydrophobic tails
- B. Long water-soluble carbon chains
- C. Positively charged functional groups
- D. Both 'B' and 'C'
Explanation: Phospholipids are essential components of cell membranes, characterized by their amphipathic nature.
Correct answer: Hydrophilic heads and hydrophobic tails1053. Fatty acids are organic compounds containing hydrogen, oxygen, and one of the following groups:
- A. Carboxylic
- B. Amino
- C. Acyl
- D. Sucrose
Explanation: Fatty acids are organic compounds characterized by a long hydrocarbon chain and a terminal carboxylic acid group.
Correct answer: Carboxylic- A. P-O-C-P-O-C
- B. C-O-P
- C. C-O-P-O-C
- D. C-C-O-P
Explanation: The correct structure of a phosphodiester bond is C-O-P-O-C, which forms between the phosphate group of one nucleotide and the hydroxyl…
Correct answer: C-O-P-O-C- A. Alcohol
- B. Glycerol
- C. Serine
- D. Cysteine
Explanation: Waxes are a type of lipid formed by the esterification of long-chain fatty acids with long-chain alcohols.
Correct answer: Alcohol- A. Fatty acids and water
- B. Fatty acid and glucose
- C. Fatty acids and alcohol
- D. Fatty acids and phosphates
Explanation: Acylglycerols, such as fats and oils, are formed through a condensation reaction between fatty acids and alcohols, resulting in ester…
Correct answer: Fatty acids and alcohol- A. Rubber
- B. Chitin
- C. Cutin
- D. Cholesterol
Explanation: Chitin is the correct answer because it is a polysaccharide, not a lipid.
Correct answer: Chitin- A. -8 C°
- B. 8 C°
- C. 63.1 C°
- D. 56 C°
Explanation: Palmitic acid is a saturated fatty acid with a 16-carbon chain, which contributes to its relatively high melting point of 63.1°C.
Correct answer: 63.1 C°- A. Phospholipid
- B. Sphingolipid
- C. Glycolipid
- D. Terpenoid
Explanation: Phosphatidylcholine is a type of phospholipid, which is a major component of cell membranes.
Correct answer: Phospholipid- A. Polymers
- B. Isomers
- C. Monomers
- D. Dimers
Explanation: The correct answer is isomers. Glucose and fructose are structural isomers, meaning they have the same chemical formula, C6H12O6, but…
Correct answer: Isomers