Question

"A suspension of chloroplasts was isolated from an aquatic plant, and a reagent was added. The reagent is blue when oxidized and is colorless when reduced. The suspension of chloroplasts in the blue reagent was exposed to sunlight. The blue color disappeared. Use your knowledge of the light-dependent reactions of photosynthesis to explain why."

A) The chloroplasts absorbed all the blue light, making the reagent colorless.
B) The reagent turned colorless due to the reduction of electrons during photosynthesis.
C) Sunlight turned the reagent blue by providing energy for oxidation.
D) Chloroplasts reflect blue light during photosynthesis, masking the color of the reagent.

Answer 1

During the light-dependent reactions of photosynthesis, the reagent in the chloroplast suspension can be reduced and become colorless. This is why the blue color of the reagent disappeared when exposed to sunlight.

Step-by-step explanation:

The light-dependent reactions of photosynthesis occur in the thylakoid membranes of chloroplasts, where pigments such as chlorophyll capture solar energy. When sunlight is absorbed by chlorophyll in the chloroplasts, it initiates a series of reactions that generate ATP and NADPH. These reactions also involve the oxidation of pigments, which can cause a reagent in the suspension of chloroplasts to be reduced and become colorless. Therefore, option B) The reagent turned colorless due to the reduction of electrons during photosynthesis, is the correct explanation for why the blue color of the reagent disappeared when the chloroplast suspension was exposed to sunlight.