A Report about Hill’s Experiments

Abstract

R. Hillelucidated quantitative evolution ofoxygen by isolated chloroplasts in 1937. His discovery made a substantial contribution to the advancement of the study of photosynthesis. Hill’s experiments comprised the three interesting methods ; the use of (1) ferricion as the electron acceptor, (2) hemoglobin as the measuring system ofoxygen evolution, and (3) isolated chloroplasts as the light reaction system.

Since high school students today only memorize the light reaction as the process to produce ATP and oxygen, and to genarate reducing power (XH₂), the light reaction itselfremain in a black box for them. They would hardly realize the light reaction without recognition of the existence of electron flow in chloroplasts. By studying Hill’s experiments ata high school, the students notonly understand exactly the light reaction, but also they have a chance to approach Hill’s originality. It seems to be very valuable for them to trace his experiments.

The purpose ofthis paper is to discuss the background ofthe use offerric ion, the quantitative analysis of evolved oxygen, and the method of chloroplastisolation following his original papers. Finally, I state how to treat the Hillreaction in bilolgical education ofthe high school.