Why does the activity of most human enzymes fall sharply above about 45 °C?
Correct answer A. The enzyme is denatured and the active site loses its shape
Topic / 35 questions
Macromolecules MCQs
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- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
According to the induced-fit model, what happens when a substrate binds to an enzyme?
Correct answer A. The active site changes shape slightly to fit the substrate closely
How does an enzyme increase the rate of a reaction?
Correct answer D. It provides an alternative pathway with a lower activation energy
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Kwashiorkor, seen in children with swollen abdomens, is caused mainly by a deficiency of ____.
Correct answer A. Protein
Which group of proteins protects the body by recognising and binding to foreign antigens?
Correct answer D. Antibodies (immunoglobulins)
What does the primary structure of a protein refer to?
Correct answer D. The sequence of amino acids in the polypeptide chain
Which linkage joins amino acids together in a protein chain?
Correct answer B. Peptide bond, –CO–NH–
The α-helix and β-pleated sheet of proteins are mainly stabilised by ____.
Correct answer A. Hydrogen bonds between C=O and N–H groups of the backbone
Which interaction is found in the tertiary structure but NOT in the secondary structure of a protein?
Correct answer B. Disulphide bridges between R groups of cysteine
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Haemoglobin is made of four polypeptide chains. This arrangement is an example of ____ structure.
Correct answer C. Quaternary
Which protein is a fibrous protein?
Correct answer A. Keratin
When a protein is denatured by heat, which level of structure normally remains intact?
Correct answer D. Primary structure
In aqueous solution near neutral pH, an amino acid such as glycine exists mainly as ____.
Correct answer B. A zwitterion, ⁺H₃N–CH₂–COO⁻
Which amino acid is essential and must be obtained from the diet by adults?
Correct answer B. Lysine
Which protein is a conjugated protein containing a non-protein prosthetic group?
Correct answer C. Haemoglobin
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