Question

The overall rate of photosynthesis is higher per unit of light energy received in flashes than continuously. Justify the statement.

Answer 1

The short periods of light would be sufficient to reduce all the carbon dioxide which could reach the cells by diffusion during the dark periods. In short, sufficiently bright flashes are alternated with long dark periods, the flash yield attains a finite, temperature-independent maximum value of one oxygen. Extension of the flash period initially yields a marked, temperature-dependent increase of the flash yield, which indicates the formation of an additional intermediate between light and oxygen. Hence, the overall rate of photosynthesis is higher per unit of light energy received in flashes than continuously.