Question

If the input water is labeled with a radioactive isotope of oxygen, 18O, then the oxygen gas released as the reaction proceeds is also labeled with 18O. Which of the following is the most likely explanation (A) During the light reactions of photosynthesis, water is split, the
hydrogen atoms combine with the CO2, and oxygen gas is released.
(B) During the light reactions of photosynthesis, water is split, removing
electrons and protons, and oxygen gas is released.
(C) During the Calvin cycle, water is split, regenerating NADPH from
NADP+, and oxygen gas is released.
(D) During the Calvin cycle, water is split, the hydrogen atoms are added
to intermediates of sugar synthesis, and oxygen gas is released.

Answer 1

Answer:

A

Explanation:

During the light stage of photosynthesis, water splits in a photolysis reaction. The hydrogen now combines with CO2 to form the sugar and the oxygen originally from the water is released back into the atmosphere.

Answer 2

Answer:

b. During the light reactions of photosynthesis, water is split, removing electrons and hydrogen ions, and oxygen gas is released.

Explanation:

During the light reactions of photosynthesis the oxygen present in the water is released.

As we know, photosynthesis happens when chlorophyll absorbs sunlight. At that time, the water and carbon dioxide captured by the plant are converted into a glucose molecule. During this process, the water is "broken", losing electrons and hydrogen ions. In this case, the oxygen ends up being thrown out of the reaction and dissolved in the environment. You can observe this process through the equation below:

6 CO2 + 12 H2O ----> C6H12O6 + 6 O2 + 6 H2O