Which of the following is the site of the photosystems in the light-dependent reactions of photosynthesis?

• A. Thylakoid membrane
• B. Outer chloroplast membrane
• C. Stroma
• D. Mitochondrial matrix

Answer: (A)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis occurs in two main stages—light-dependent reactions and the Calvin cycle. The light-dependent reactions capture light energy to produce ATP and NADPH, which are used in the Calvin cycle.
2. Identify the location of the light-dependent reactions: These reactions occur in the chloroplasts, specifically within the thylakoid membranes. The thylakoid membranes contain the photosystems (Photosystem I and Photosystem II) that are essential for capturing light energy.
3. Learn about the photosystems: Photosystem I and Photosystem II are protein-pigment complexes embedded in the thylakoid membrane. They play a key role in absorbing light and facilitating the transfer of electrons during the light-dependent reactions.
4. Compare the options provided: The outer chloroplast membrane is not involved in the light-dependent reactions. The stroma is the fluid-filled space in the chloroplast where the Calvin cycle occurs, not the light-dependent reactions. The mitochondrial matrix is part of the mitochondria and unrelated to photosynthesis.
5. Conclude that the correct answer is the thylakoid membrane, as it is the site where the photosystems are located and where the light-dependent reactions of photosynthesis take place.