2.5a IB Bio Enzymes

A substrate is a

• reactant in a biochemical reaction

• product of a biochemical reaction

The active site is the

• region on the surface of a substrate to which enzymes bind

• region on the surface of an enzyme to which substrates bind

An enzyme is a a globular protein that increases the rate of a biochemical reaction by

• lowering the activation energy threshold

• raising the activation energy threshold

1. What suffix is commonly applied to enzymes?

• -ose

• -ate

• -ise

• -ase

If the lock-and-key model were true, one enzyme would only catalyze one reaction. In actuality,

• enzymes cannot catalyse reactions.

• some enzymes can catalyse multiple reactions.

• all enzymes can catalyse multiple reactions.

Why is water critical for most enzyme reactions? All molecules dissolved in water are in random motion.

• Enzymes are always stationary and collisions are the result of random movements of the substrate only.

• Collisions are the result of the random movements of the enzyme only.

• Collisions are the result of the random movements of both substrate and enzyme.

Why do enzymes tend to move more slowly than substrates?

• Enzymes tend to be smaller than substrates and therefore move more slowly.

• Enzymes tend to be larger than substrates and therefore move more slowly.

What can occur to an enzyme that disables its ability to catalyze reactions?

• denaturation

• increase in substrate concentration

• addition of fatty acids

Which of these graphs represents the rate of enzyme reactions under increasing temperature?

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Which of these graphs represents the rate of enzyme reactions under increasing pH levels?

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