Question

Which one of the following options is true in photosynthesis?
A)$CO_2$ is oxidised and $O_2$ is reduced
B) $H_2O$ is oxidised and $CO_2$is reduced
C) Both $H_2O$ and $CO_2$ are reduced

Answer 1

Hint:Photosynthesis can be divided into two stages- the light dependent reaction and the light independent reaction. Photosynthesis happens as water and carbon dioxide are absorbed by the plant. Then they are converted into sugar and oxygen.

Complete answer:
Reactions involving electron transfer are also known as oxidation-reduction reactions, or simply redox reactions. The atom that loses electrons is oxidised and the atom that receives electrons is diminished.

In green plants $H_2O$ is the hydrogen donor and is oxidised to $O_2$.An electron is removed from a molecule of water releasing the atoms of oxygen and hydrogen during the light reactions. The free oxygen atom joins with another free oxygen atom to create oxygen gas that is then released.

In the process also referred to as carbon fixation, the energy produced by the light reactions from the ATP and NADPH molecules drives a chemical pathway using carbon dioxide to produce a three-carbon sugar known as glyceraldehyde-3-phosphate (G3P). This sugar is then used by cells to create a broad range of other sugars and organic molecules.

Thus, during photosynthesis, the water is oxidized (loses electrons) and the CO2 is reduced (gains electrons). Photosynthesis uses light energy to push electrons from water to their more energetic state in sugar products, thus transforming solar energy into chemical energy.

The reaction involved in the process of photosynthesis is as follows:-
\[C{O_2} + {H_2}O\xrightarrow[{Green\,\,plants}]{{Sunlight}}{O_2} + Organic\,\,matter\]

Note:The effect of genetic drift is higher when there are less copies of an allele, and the effect is lower when there are more copies. Ronald Fisher, who used Mendelian genetics to explain natural selection, held the opinion that genetic variation plays a small role in evolution at most, and for many decades, this became the dominant view.