Biological Molecules Practice Questions
A-Levels · A-Level Biology · 146 free MCQs with instant results and detailed explanations.
146
Total
44
Easy
72
Medium
30
Hard
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Sample Questions from Biological Molecules
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
Which of the following is a characteristic feature of enzymes?
A.
They are consumed in the reaction.
B.
They lower the activation energy of reactions.
C.
They are only found in prokaryotic cells.
D.
They can catalyze any reaction.
Show Answer & Explanation
Correct Answer: B
Enzymes are biological catalysts that lower the activation energy of chemical reactions, making them proceed faster without being consumed in the process.
Q2
Easy
Which of the following molecules is classified as a carbohydrate?
A.
Glycine
B.
Glucose
C.
Lysine
D.
Thymine
Show Answer & Explanation
Correct Answer: B
Glucose is a simple sugar and is classified as a carbohydrate, while glycine is an amino acid, lysine is another amino acid, and thymine is a nucleotide base.
Q3
Easy
Which type of bond forms the primary structure of proteins?
A.
Ionic bonds
B.
Hydrogen bonds
C.
Peptide bonds
D.
Disulfide bonds
Show Answer & Explanation
Correct Answer: C
Peptide bonds link amino acids together to form the primary structure of proteins, while ionic, hydrogen, and disulfide bonds contribute to secondary and tertiary structures.
Q4
Medium
Which of the following is the primary structural component of the cell membrane?
A.
Phospholipids
B.
Proteins
C.
Carbohydrates
D.
Nucleic acids
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Correct Answer: A
Phospholipids form a bilayer in the cell membrane, providing structural integrity, while proteins, carbohydrates, and nucleic acids play other roles.
Q5
Medium
What type of bond forms between amino acids during protein synthesis?
A.
Ionic bonds
B.
Hydrogen bonds
C.
Peptide bonds
D.
Disulfide bonds
Show Answer & Explanation
Correct Answer: C
Peptide bonds are covalent bonds that link amino acids together in a polypeptide chain during protein synthesis.
Q6
Medium
Which of the following biomolecules is the primary energy source for cells?
A.
Proteins
B.
Lipids
C.
Carbohydrates
D.
Nucleic acids
Show Answer & Explanation
Correct Answer: C
Carbohydrates are primarily used by cells for energy due to their quick conversion to glucose, which is readily used in cellular respiration.
Q7
Medium
Which of the following describes a function of nucleotides in living organisms?
A.
Energy carriers
B.
Structural components of membranes
C.
Enzymatic catalysts
D.
Storage of genetic information
Show Answer & Explanation
Correct Answer: A
Nucleotides, such as ATP, serve as energy carriers in cells, facilitating the transfer of energy for biochemical reactions.
Q8
Hard
Which of the following statements about enzymes is TRUE?
A.
Enzymes increase the activation energy required for reactions.
B.
Enzymes can be consumed in the reaction they catalyze.
C.
Enzymes are specific for their substrates due to their active site structure.
D.
Enzymes function optimally at all temperatures.
Show Answer & Explanation
Correct Answer: C
Option C is correct because enzymes have a specific active site that fits only particular substrates, ensuring high specificity in catalyzing biochemical reactions. The other options are incorrect as enzymes lower activation energy, are not consumed in reactions, and have optimal temperature ranges.
Q9
Hard
Which of the following statements about enzymes is TRUE?
A.
Enzymes lower the activation energy of a reaction.
B.
Enzymes are consumed in the reactions they catalyze.
C.
Enzyme activity is unaffected by temperature changes.
D.
All enzymes have the same optimal pH.
Show Answer & Explanation
Correct Answer: A
Enzymes act as catalysts by lowering the activation energy required for a reaction to occur, thereby increasing the rate of the reaction without being consumed in the process.
Q10
Hard
A biochemist synthesizes a new polysaccharide. If it consists of 50 glucose units linked by ฮฑ-1,4 glycosidic bonds, what is the maximum number of water molecules that could be released during its formation?
A.
49
B.
50
C.
51
D.
48
Show Answer & Explanation
Correct Answer: A
For every glycosidic bond formed between two glucose units, one water molecule is released. Therefore, with 50 glucose units, 49 bonds are formed, resulting in the release of 49 water molecules.
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Biological Molecules โ A-Levels A-Level Biology Practice Questions Online
This page contains 146 practice MCQs for the chapter Biological Molecules in A-Levels A-Level Biology. The questions are organized by difficulty โ 44 easy, 72 medium, 30 hard โ so you can choose the right level for your preparation.
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