Question

The “Saturation Point” experiment demonstrates that adding more substrate molecules increases the reaction rate up to a certain point, but then adding even more substrate doesn’t make the reaction go any faster. What biological principle explains this plateau effect?
Question 9 options:

All enzyme active sites become occupied, so additional substrate molecules must wait for availability

Enzyme molecules get tired from working too much and need time to rest and recover

Extra substrate molecules combine uselessly with enzyme molecules and interfere with their function

Too much substrate becomes toxic and poisonous to the enzyme molecules, slowing them down

Answer 1

All enzyme active sites become occupied, so additional substrate molecules must wait for availability.

Explanation: once every enzyme molecule is bound to substrate (saturation), the reaction rate reaches Vmax and is limited by how fast enzymes can convert bound substrate to product (kcat). Adding more substrate can't increase the rate until enzymes become free again.