HELP - Cumulative vs. prereq vs. undergrad GPA???

Hi!!

I have been looking through the list of programs I would like to apply to (a very very long one, I might add...) and I noticed that there are usually different types of GPAs that they ask you to provide:

1. Prereq GPA/Science GPA (I'm assuming this means A&P, micro, chem, biochem, etc)
2. Undergraduate GPA (if you have a degree already)
3. Last 90 units
4. Cumulative GPA


I understand #1 and #2. What I don't fully understand are #3 and #4.

A lot of programs require you to have a certain GPA in order to apply to their programs, but based on which GPA?

When they ask for "cumulative GPA," do they want my undergrad GPA + my science prereq GPA?
[This one's important because my undergrad GPA alone did not get up to 3.0, but if i included my science prereq classes, it would boost up my GPA]

If they're only asking for my last 90 units of my undergrad GPA, do just calculate my 90 units even if I had Pass/No Pass classes? Or am I calculating my GPA based on the last 90 units of classes that I took for a letter grade only?
[And this is confusing because my undergrad was on the quarter system, so the conversions are already kind of tricky in itself]

I know that I probably should ask the schools directly, but I have so many programs that I'd like to potentially apply to that I figured I'd ask here first. I'm sure someone will have this info and once I have a general understanding, I can maybe ask the schools specifically just to clarify.


Thank you in advance for your help!!! Any any any input would be awesome!! And good luck to all those applying this fall!!!

-hmpark