Bio major here.
I only had one semester of organic and biochemistry each. I had the same concerns you did, and one of my interviewers (at program I was accepted) said I had an "interesting background" not sure if that was a euphemism for poor preparation, or if having a broader understanding of plant biology and ecology with an interest in getting into biochem/biophysics was seen as an asset. Who knows?!
Anyway don't count yourself out! and I would advise against taking the biochem GRE unless you seriously devote yourself to preparing for it. Play to your strengths, much better to nail the biology GRE than get an average biochem score, or even worse, bomb it
For the record, my favorite science class ever was field botany, nothing to make you feel close to Darwin than keying out wildflowers on a hilltop meadow