Page 06 11. An enzyme-controlled reaction is taking place in optimum conditions in the presence of a large surplus of substrate. Conditions can be altered by 1 increasing the temperature 2 adding a positive modulator 3 increasing enzyme concentration 4 increasing substrate concentration. Product yield would be increased by A 1 and 2 B 2 and 3 C 2 and 4 D 3 and 4. 12. At which phase of the cell cycle is the retinoblastoma protein phosphorylated allowing progression to the next phase of the cycle? A G1 B S C G2 D M