And so the rate law is v is equal to K. And notice that changing A, either increasing or decreasing will not affect the value of V. And some enzyme catalyze reactions inside our body are in fact 0th order. And what that means is by changing the concentration of A that will not affect that rate of the reaction. Now we can also have something known as a pseudo first order reaction. And a pseudo first order reaction is actually a second order reaction that behaves like it's a first order reaction. Now what's one example of such a reaction? Well, let's suppose is we have a second order reaction as shown, but the concentration of A is very tiny but the concentration of B is very, very high.