Photosynthesis light harvesting: A group of ~300 chlorophyll molecules that cooperatively capture light and funnel energy to a reaction center is called what?

Introduction / Context:
Light energy is captured not by isolated chlorophylls but by organized assemblies in thylakoid membranes. Recognizing the terminology for these assemblies reinforces understanding of energy transfer in photosystems I and II.

Given Data / Assumptions:

• Approximately 200–400 chlorophyll molecules act cooperatively.
• Energy is funneled to a special pair in the reaction center.
• The term that encompasses the collective harvesting module is sought.

Concept / Approach:
The classic term “photosynthetic unit” denotes the ensemble of many antenna pigments plus the reaction center they feed. The antenna portion alone is often called the “harvesting unit” or “antenna complex,” but the definition in the stem (capture and transfer to reaction center) fits the photosynthetic unit usage found in many texts.

Step-by-Step Solution:

Verification / Alternative check:
Classic measurements estimate one O2 evolved per ~2500 chlorophyll excitations, implying large, cooperative pigment arrays—the photosynthetic unit concept.

Why Other Options Are Wrong:

Common Pitfalls:
Using “antenna complex” and “photosynthetic unit” interchangeably; antenna is a component, the unit includes the reaction center coupling.

Final Answer:
Photosynthetic unit.