I just finished a general biology course at my university (covering cellular/molecular biology, function, and structure). Also, received an A+ too! :)
Our textbook was Campbell Biology. I will say that this biology text unequivocally is one of the best textbooks I've ever read (well, 300+ pages of the 1200+ page text anyway). Anyone not in the position to take a college class but wants to learn more about biology, the 9th edition of the book can be had on eBay for about $35 (sometimes less, I got mine for $18). It's full of great illustrations and high quality photographs.
Compared to what JWs "teach" you about biology, like on the topic of the cell, dna, and thermodynamics, this book is a delight. It also integrates well how evolution relates to each and every topic in biology. As Theodosius Dobzhansky says, "Nothing in Biology Makes Sense Except in the Light of Evolution."
I wish I could buy a copy and give it all my JW family members. But I doubt they'd be inclined to even let me give it to them, let alone read it.