Question

type of enzyme that speeds up chemical reactions
active site
catalyst
lock & key
factors that affect enzyme activity

Explanation:

To determine the correct option, we analyze each choice:

• "Active Site" is the region on an enzyme where the substrate binds, not the type of enzyme that speeds up reactions.
• "Catalyst" is a substance (including enzymes, which are biological catalysts) that speeds up chemical reactions by lowering the activation energy. Enzymes are biological catalysts, so this fits the description of a type of enzyme (or the role of enzymes) that speeds up chemical reactions.
• "Lock & Key" is a model describing how enzymes and substrates interact, not the type of enzyme for speeding up reactions.
• "Factors that affect Enzyme Activity" refers to things like temperature, pH, etc., that influence how well an enzyme works, not the type of enzyme that speeds up reactions.

Answer:

B. Catalyst