Experiment Facts

This is because a high temperature has a tendency to inactivate chloroplasts. Using a cold temperature will preserve the components of the plant sample cells as they were.

B. The use of salts, such as NaCl, does not significantly affect the photosynthetic potential of the leaves of a plant thus, it is ideal for the experiment. It was used in the grinding the papaya leaves to keep the chloroplasts active. It was also used in suspension because it aggregates chloroplasts. No

C. Pellet I was discarded because it contains the nuclei, starch and other cell debris that are not needed in the experiment.

D. This is because the chloroplasts are expected to form pellets when the relative centrifugal force is less than or equal to 1400 x g. The time is relatively longer than that of the first centrifugation so that the distance covered by the chloroplast particles will be higher (since, d=vt) and hence, more particles will settle at the bottom of the tube.

F. Since the evolution of oxygen is too small to be accurately measured in the absence of carbon dioxide, a specific concentration of chloroplasts was used. It was diluted because at a low concentration of chlorophyll, the Hill reaction will be Co2-dependent.

2. The control setup contains denatured chloroplasts while, the experimental setups had active chloroplasts. Hence, different wavelengths will be absorbed by the different setups.

3. Because of homogenization and centrifugation, the thylakoid membrane is already disrupted and the electron transport chain does not function normally anymore. The presence of the oxidized 2,6-dichlorophenolindophenol (or DPIP), when triggered by light, will be reduced by the excited electrons from the chlorophyll. The nitrogen connecting two benzyl groups would change from 1 double bond and 1 single bond to 3 single bonds. This results to a change in conformation of the structure (see figure 6.1) )and thus, the light reflecting property of the DPIP also changes.

5.