During the pentose phosphate pathway, glucose 6-phosphate is first converted into 6-phosphoglucono-lactone in the reaction catalyzed by glucose 6-phosphate dehydrogenase. The 6-phosphoglucono-lactone is then converted into 6-phospho-gluconate which in turn undergoes decarboxylation to form D-ribulose 5-phosphate and the C-1 of original glucose 6-phosphate is released in form of CO2.
Therefore, to observe the most rapid production of labeled carbon atom in form of CO2, the C-1 of glucose should be labeled.
The correct answer is the fourth option. The magnification of a specimen viewed with a compound light microscope that has an objective power of 10x and an ocular lens power of 5x is equal to 50x. Magnification is equivalent to the product of the objective power and the ocular lens. Ten times five is fifty.