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IB Biology C1.1: Enzy. & Meta. — Practice Questions & Answers
IB Biology C1.1 Enzymes and metabolism study notes: active sites, induced fit, factors affecting activity, inhibition and metabolic pathways.
Here are 10 practice questions with full answers and explanations.
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Practice questions with answers
1
Multiple choice
What is the primary function of enzymes in biological systems?
To catalyze and increase the rate of reactions
To act as static structural components for cellular scaffolding
To store genetic information
To transport molecules across cell membranes
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Why Enzymes are biological catalysts that speed up the rate of metabolic reactions.
2
Multiple choice
What is metabolism?
The complex network of chemical reactions occurring in living organisms
The physical breakdown of food into smaller particles
The synthesis of proteins
The breakdown of glucose
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Why Metabolism is the entire network of enzyme-catalysed chemical reactions occurring within living organisms.
3
Multiple choice
What is an anabolic reaction?
The formation of macromolecules from monomers.
The breakdown of macromolecules into monomers.
The oxidation of substrates in respiration.
The process of diffusion across cell membranes.
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Why Anabolic reactions build larger macromolecules from smaller monomers, requiring energy input.
4
Multiple choice
Which of the following is an example of an anabolic reaction?
Protein synthesis.
Digestion of carbohydrates.
Cellular respiration.
Hydrolysis of lipids.
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Why Protein synthesis is anabolic because amino acid monomers are joined to build polypeptide macromolecules.
5
Multiple choice
What is a catabolic reaction?
The hydrolysis of macromolecules into monomers.
The synthesis of macromolecules.
The process of photosynthesis.
The formation of glycogen.
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Why Catabolic reactions break down macromolecules into monomers, typically by hydrolysis, releasing energy.
6
Multiple choice
Which of the following is an example of a catabolic reaction?
Hydrolysis of proteins
Formation of DNA
Synthesis of lipids
Production of glucose in photosynthesis
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Why Hydrolysis of proteins is catabolic, splitting polypeptides into amino acids by adding water.
7
Multiple choice
What type of protein are enzymes?
Globular proteins.
Fibrous proteins.
Membrane proteins.
Structural proteins.
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Why Enzymes are globular proteins whose folded tertiary structure creates a specific active site.
8
Multiple choice
What is the active site of an enzyme?
The region where the substrate binds.
The region that determines the enzyme's overall shape.
The region that stores energy.
The region that synthesizes amino acids.
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Why The active site is the region of an enzyme where the substrate binds and catalysis occurs.
9
Multiple choice
What is induced-fit binding?
Both the substrate and enzyme change shape upon binding.
Only the substrate changes shape.
Only the enzyme changes shape.
Neither the substrate nor the enzyme changes shape.
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Why In induced fit, the enzyme and substrate both change shape slightly to form a tighter, catalytic complex.
10
Multiple choice
What is the role of molecular motion in enzyme catalysis?
It allows substrate-active site collisions.
It denatures the enzyme.
It increases the activation energy.
It inhibits enzyme activity.
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Why Random molecular motion brings substrates and active sites together, enabling collisions that lead to binding.
Key terms in Enzy. & Meta.
Enzyme: A globular protein that acts as a biological catalyst, speeding up a specific reaction without being used up.
Active site: The region of an enzyme with a shape complementary to its substrate, where catalysis occurs.
Activation energy: The minimum energy needed for a reaction to proceed; enzymes work by lowering it.
Induced fit: The model in which the active site changes shape slightly as the substrate binds, improving the fit.
Denaturation: The loss of an enzyme’s functional shape, and therefore activity, usually caused by high temperature or extreme pH.
Competitive inhibitor: A molecule resembling the substrate that binds to the active site and blocks it; its effect is reduced by adding more substrate.
Non-competitive inhibitor: A molecule that binds away from the active site (allosteric site), altering the enzyme’s shape so the substrate no longer fits.
Anabolism: Metabolic reactions that build larger molecules from smaller ones, requiring energy (for example, condensation).
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