Thylakoids contain clusters of chlorophyll and proteins known as:

• A. stroma
• B. photosystems
• C. stomata
• D. grana

Answer: (B)

Verified step by step guidance

1. Understand the structure of a chloroplast: Chloroplasts are organelles in plant cells where photosynthesis occurs. They contain thylakoids, which are membrane-bound compartments stacked into structures called grana.
2. Learn the role of thylakoids: Thylakoids are the site of the light-dependent reactions of photosynthesis. These reactions involve capturing light energy to produce ATP and NADPH.
3. Identify the components within thylakoids: Thylakoid membranes contain clusters of chlorophyll molecules and proteins that work together to capture light energy. These clusters are known as photosystems.
4. Differentiate between the options: Stroma refers to the fluid-filled space surrounding the grana, stomata are pores on the leaf surface for gas exchange, and grana are stacks of thylakoids. Photosystems are the correct answer as they are the functional clusters within thylakoids.
5. Conclude that photosystems are the correct answer: Photosystems (Photosystem I and Photosystem II) are essential for the light-dependent reactions, as they absorb light and transfer energy through the electron transport chain.