Question

Suppose the interior of the thylakoids of isolated chloroplasts and then transferred in the dark to a pH 8 solution. What would be likely to happen?
A. The isolated chloroplast will make ATP
B. The Calvin cycle will be activated
C. The cyclic photophosphorylation will occur
D. Isolated chloroplast will generate oxygen gas

Answer 1

Hint: The chloroplasts contain the green pigment of the leaves required for the process of photosynthesis and the production of food and energy for the plant. The optimal level of pH at which chloroplast function is 7-8.

Complete answer:
We all have studied the process of photosynthesis where the light energy is taken and it is converted into chemical energy and along with it the plant also takes up carbon dioxide from the outside and uses it in photosynthesis releasing oxygen into the atmosphere. This all activity is carried out in the chloroplast as it contains chlorophyll.
Now let us assume that the chloroplasts before isolation were in light and then they were transferred into dark. By this time, they might have trapped certain sunlight. Now the optimum pH for the functioning of the chloroplast is 7-8 and it increases its capacity as pH is increased up to a certain level.
Now as the pH of the solution is optimum and the chloroplast already has sunlight then as a result the chloroplast will start transforming the sunlight into the chemical energy required by plants in the form of ATP.
The Calvin cycle can not be started because it requires the availability of citric acid which is not present in the chloroplast and for the process of photophosphorylation to occur the chloroplast requires light which is not available at the moment.

So, the correct option is Option A.

Note:
We all know that plants take up carbon dioxide and they as a result of respiration release the oxygen gas. But in this case, we have isolated chloroplasts and the trapping of carbon dioxide and release of oxygen occurs through stomata which is not present at the moment.