Is this paragraph grammatically correct?

My favorite cl this semester is Human Biology. I went into the semester dreading the online cl and feared I would struggle through it. The processes of the human body are enough to boggle the mind; from its genetic make-up to its effects on the biosphere, the complexity of human life is amazing. Despite my fears prior to the start of the semester, I really enjoy the subject matter, and my interest has caused me to do well in the cl. Human Biology has been a lot of work, but I find it all very rewarding.