Answer the following question given this paragraph: 

Enzymes are extremely efficient in speeding up reactions. They can catalyze up to several million reactions per second. As a result, the difference in rates of biochemical reactions with and without enzymes may be enormous. A typical biochemical reaction might take hours or even days to occur under normal cellular conditions without an enzyme, but less than a second with an enzyme.


Q: Enzymes in cellular reactions work to do what to the reaction?

 Choices:

- increase yield

- decrease heat

- slow it down

- speed it up

A:
speed it up
