Question

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH-8 solution. What would be likely to happen?A. The isolated chloroplasts will make ATP B. The Calvin cycle will be activated C. Cyclic photophosphorylation will occur D. Only A and B will occur E. A, B and C will occur

Answer 1

The isolated chloroplasts placed in a dark, pH-8 solution after being acidified will most likely synthesize ATP due to the existing proton gradient which drives ATP synthesis through ATP synthase, despite the absence of light.

Step-by-step explanation:

The question presented involves the light-dependent reactions of photosynthesis that occur in the thylakoid membranes of chloroplasts. When the interior of thylakoids is made acidic and then placed in a dark, pH-8 solution, the most likely event is that the isolated chloroplasts will synthesize ATP. This is because the proton gradient created by the acidic interior compared to the basic exterior can drive the synthesis of ATP through the protein complex ATP synthase, even in the absence of light. The Calvin cycle, also known as the light-independent reactions, wouldn't be activated in the dark because it relies on the products (ATP and NADPH) of the light-dependent reactions, which require light to occur. As for cyclic photophosphorylation, this process can indeed occur in light as a way to produce additional ATP when necessary; however, it also requires light to energize electrons, so it would not occur in this scenario. Therefore, the correct answer is D, only A and B will occur.

Answer 2

The correct answer will be option-A

Step-by-step explanation:

Thylakoid is the structure in the chloroplast where the light-dependent reaction takes place which forms the ATP and NADPH.

The production of ATP takes place due to the movement of Hydrogen ions across the membrane from the interior or lumen to the stroma of the chloroplast.

If the thylakoid were made acidic that is hydrogen ion concentration increases inside the lumen and then kept in a basic solution where the hydrogen concentration is low then it will lead to generation of a proton gradient.

The generation of the proton gradient will cause the movement of the protons from the lumen to the outside through ATP synthase which will produce ATP.

Thus, option-A is the correct answer.