Question
Answers

Hill reaction occurs in
(a)High altitude plants
(b)Total darkness
(c)Absence of water
(d)Presence of ferricyanide

Answer Verified Verified
Hint: During photosynthesis, there are two types of reactions seen namely light and dark depending upon the requirement of light energy. Hill reaction is an important part of the light reaction.

Complete answer:
In the presence of suitable electron acceptors like potassium ferrioxalate and potassium ferricyanide, oxygen is produced due to the photochemical splitting of water. This is known as the Hill reaction. This takes place in the presence of light.
The spilling of water during photosynthesis is called photolysis.
Hill reaction
$4Fe^{3+} + 2H_{2}O\longleftrightarrow 4Fe^{2+} +4H^{+} + 2O_{2}\uparrow$

Additional Information:
 Light reactions occur in a grana fraction of chloroplast and in this reaction are included those activities which are dependent upon light. Assmilitary powers like ATP and NADP are mainly produced in this light reaction
Hill’s reaction proves that in photosynthesis oxygen is released from water. Electrons for the reduction of carbon dioxide are obtained from water (a reduced substance {hydrogen donor} is produced which later reduces to carbon dioxide). According to Arnon, in this process, light energy is converted into chemical energy. This energy is stored in ATP and this process of ATP formation in the chloroplast is known as phosphorylation.
So, the correct answer is ‘the presence of ferricyanide’

Note: -In phosphorylation, from electron acceptor ${ NADP }^{ + }$, a substance found in all living beings, NADP + ${ H }^{ + }$ is formed as a hydrogen donor.
-The formation of hydrogen donor NADPH is known as photoreduction or production of reducing power NADPH.
-Hill’s reaction was given by Robert Hill and is named after him.
-Dichlorophenolindophenol is the dye used for hill reaction.