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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- A. Saturated
- B. Unsaturated
- C. All
- D. None
Explanation: Saturated fats are solid at room temperature because their molecular structure is straight and allows for tight packing, which is typical…
Correct answer: Saturated822. Fats and oils are:
- A. Lighter than water
- B. Heavier than water
- C. Less viscous than water
- D. More denser than water
Explanation: Fats and oils have a specific gravity of about 0.8. That is why they are lighter and have a lower density than water.
Correct answer: Lighter than water- A. Phospholipid
- B. Phosphatidic acid
- C. Phosphatidylcholine
- D. Phosphatidylethanolamine
Explanation: The correct answer is phosphatidic acid. When glycerol, fatty acids, and phosphoric acid combine, they form phosphatidic acid, which is…
Correct answer: Phosphatidic acid- A. Phosphatidic acid
- B. Phosphatidylcholine
- C. Phospholipid
- D. Lecithin
Explanation: The correct answer is Phosphatidylcholine. When phosphatidic acid combines with a nitrogenous base like choline, it forms…
Correct answer: Phosphatidylcholine- A. One molecule of water
- B. Two molecules of water
- C. Three molecules of water
- D. Four molecules of water
Explanation: During the condensation reaction of glycerol with two fatty acids and one phosphoric acid to form phosphatidic acid, three ester bonds are…
Correct answer: Three molecules of water- A. Triacylglycerol
- B. Diacylglycerol
- C. Monoacylglycerol
- D. Monoglyceride
Explanation: Triacylglycerol, also referred to as triglyceride, is the most widely spread acylglycerol because it is the primary form of stored energy…
Correct answer: Triacylglycerol- A. Monomers, Dehydration
- B. Subunits, Reduction
- C. Multimers, Dehydration
- D. Monomers, Hydrolysis
Explanation: Biological macromolecules are large molecules essential for life, formed from smaller units called monomers.
Correct answer: Monomers, Dehydration828. Which one of the following characteristics is not common among carbohydrates, lipids, and proteins?
- A. They are composed of a carbon backbone with functional group attached
- B. They all play a role in cell signaling and communication
- C. Their polymers are broken apart by hydrolysis
- D. The molecules are held together by ionic bondings
Explanation: The molecules of all carbohydrates, lipids and proteins are held together by covalent bonds and not ionic bonds.
Correct answer: The molecules are held together by ionic bondings- A. Phosphatidylcholine
- B. Lethanolamine
- C. Phosphatidylserine
- D. Phosphatidic acid
Explanation: The first phospholipid identified in biological tissues was phosphatidylcholine, also known as lecithin.
Correct answer: Phosphatidylcholine- A. Hydrophobic head
- B. Hydrophilic head
- C. Hydrophilic tail
- D. Hydrophobic tail
Explanation: Phospholipids are composed of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.
Correct answer: Hydrophilic head- A. Glycerol
- B. Choline
- C. Phosphoric acid
- D. Fatty acids
Explanation: Phospholipids are crucial components of cell membranes, featuring a unique structure with a hydrophilic (water-attracting) head and…
Correct answer: Fatty acids- A. 01
- B. 02
- C. 01 and 02
- D. 03
Explanation: In phosphatidic acid, the glycerol molecule has two fatty acids attached to the first and second carbons, forming ester bonds.
Correct answer: 01 and 02- A. 01
- B. 02
- C. 03
- D. 04
Explanation: Phosphatidic acid is formed when two fatty acids are esterified to the first and second carbon atoms of glycerol, and phosphoric acid is…
Correct answer: 03- A. First fatty acid
- B. Second fatty acid
- C. Phosphoric acid
- D. Glycerol
Explanation: In the synthesis of a phospholipid, the nitrogenous base is attached to the phosphoric acid, which in turn is connected to the glycerol…
Correct answer: Phosphoric acid- A. Carbohydrates
- B. Proteins
- C. Nucleic acids
- D. Lipids
Explanation: Lipids having a maximum number of C - H bonds are capable to store maximum potential energy as compared to equal amounts of carbohydrates…
Correct answer: Lipids- A. Birds
- B. Fur containing animals
- C. Insects
- D. Birds and fur containing animals
Explanation: A thin coating of fats on the fur of animals and the feathers of birds saves them from absorbing rainwater and enables them to…
Correct answer: Birds and fur containing animals- A. Hormones
- B. Antibodies
- C. Enzymes
- D. Immunoglobulins
Explanation: Enzymes are proteins that play a crucial role in controlling the entire metabolism of the cell.
Correct answer: Enzymes- A. Lipids
- B. Proteins
- C. Nucleic acids
- D. Carbohydrates
Explanation: Proteins are the most versatile biomolecules, performing numerous functions such as enzymatic activity, structural support, transport…
Correct answer: Proteins- A. Immunoglobulins
- B. Enzymes
- C. Albumins
- D. Hemoglobin
Explanation: Hemoglobin is the correct answer because it is a specialized carrier protein designed to transport oxygen and carbon dioxide in the…
Correct answer: Hemoglobin- A. Albumin
- B. Fibrin
- C. Globulin
- D. Keratin
Explanation: Fibrin is the protein responsible for preventing blood loss after injury by forming a stable blood clot.
Correct answer: Fibrin