1) what is diff between osmolarity and molarity? is osmolarity the difference of molarity in a cell and the outside? 2) are both enzymes and substrates pH specific? i know that enzymes are, but are substrates pH specific too? 3) increassing enzyme concentration increases the enzymatic reaction if substrate concentration is held constant right? 4) I know that yeast cells can undergo both respiration and fermentation, does that mean yeast cells have mitochondria too? 5) In a mitotic phase, i know that 90% of the time the cell is in prophase, but what about the other 10%? Are metaphase, anaphase, and telephase happening in equal proportions? 6) how is optical density diff than absorbance?