Which one topic or concept has been the most difficult for you so far in this course (from either The chemistry of Life, Acid-base balance, or Cellular Form and function)? Choose one topic.  What specifically is "muddy" or not quite clear about that topic?  Please be as specific as possible in identifying the topic.  For example, "I can't figure out why enzymes don't work so well in different pH's."  After identifying the topic, try to elaborate on what you know thus far about it and/or ask specific questions(s) about it. 

200 words. No Plagarism No shordy work