Figure 3.

Dependence of relative electron transport rate (ETR) on O₂ during CO₂-limited photosynthesis in S. 7942 (A), Euglena gracilis (B), and Phaeodactylum tricornutum (C). To remove dissolved O₂, d-glucose (5 mM), catalase (250 units mL⁻¹), and glucose oxidase (5 units mL⁻¹) was added to the fresh media containing the cells (10 μg Chl a mL⁻¹). Photon flux densities of white actinic light (AL) were 300 μmol photons m⁻² s⁻¹ for S. 7942 and E. gracilis; 400 μmol photons m⁻² s⁻¹ for P. tricornutum. Triangles, inverse triangles, and squares represent three independent measurements, respectively.