Light reaction in green plant photosynthesis:a method of study.

Frozen green plants (Chlorella) carry out a photoreaction which can be assayed by measuring the light produced when the sample is heated. Heating at a rate of several degrees per second gives a measurable signal which shows that green plants can store energy at very low temperatures. The absorption cross section for the unit which carries out the photoreaction is several hundred times larger than that for one chlorophyll molecule, an indication that these are the "photosynthetic units" of photosynthesis.