Well, most active and passive basses when you don't use EQ are very similar. After all, the front end of your head is basically an active preamp! An active bass merely moves part of that EQ circuit into the bass where it more convenient to adjust while you are playing.
In the Common Application, it says that the Personal Essay should be at least 250 words, and attached on a separate sheet (presumably, if you're submitting it online, you attach a one-page file).
I'm think that essay must have more than four paragraphs: The first paragraph should introduce your audience (generally your teacher or classmates) to your chosen topic. The second paragraph should expand on and support the idea you approached in your first paragraph, with two additional supporting paragraphs.