1.)What do enzymes do to the rate of a reaction? Slow them down.
Speed them up.
They do not affect the rate of a reaction.
They sometimes speed up the reaction and sometimes slow it down.

2.)The activation energy is the amount of energy needed to start a reaction. What do enzymes do to the activation energy of a reaction?
Lower it
Raise it
Don't affect it at all
Sometimes lower and sometimes raise

3.)What is a substrate?

A small enzyme.
A large enzyme.
What an enzyme works on.
The products of a reaction.

4.)What is the active site of an enzyme?

Where all inhibitors (no matter the kind) bind.
Where the substrate binds to the enzyme.
Where an enzyme is turned off.
Where an enzyme actively slows down all reactions.

1.) Speed them up

2.) Lower it

3.) What an enzyme works on

4.) Where the substrate binds to the enzyme

Explanation:

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!