Question

In cells, __________ are proteins that are needed to lower the amount of energy required to start chemical reactions.

a. acids
b. enzymes
c. products
d. substrates

Answer 1

The answers would be B.
Enzymes accelerate or catalyze ( slow or stop) chemical reactions. And enzymes are protein molecules.
While A, C, and D are not.

Answer 2

b. enzymes

Step-by-step explanation:

For any reaction to happen, an energy barrier must be crossed first. This is called as activation energy. Enzymes are biological catalysts that lower the activation energy for a reaction. As a result the reaction is started sooner and its rate is fast.

The substrate binds to the active site of enzyme to form a substrate-enzyme complex. The reaction takes place and product is formed also releasing the enzyme back so that it can be used again.