Question

In plants, hill reaction occurs

• A. All the time
• B. Only in day time
• C. Only when the plants are grown in cold climate of hills
• D. When the plant carries out up hill task of slat absorption and food translocation

Answer 1

Answer: (B)

Only in day time

Experiments with isolates chloroplasts, in presence of oxidants like ferricyanides and benzoquinone (Hill reagents) were conducted by Hill in 1937 and 1939. By placing the isolated chloroplasts in sunlight, he notices evolution of oxygen from water. Hill concluded that if there was suitable hydrogen acceptor in the medium it would have been reduced. In absence of light Hill reaction can not be possible. So, it can say it occurs only in day time.