Question

In plants, the water molecules split into hydrogen and oxygen with the help of _________ energy
A)Light
B)Chemical
C)Mechanical
D)Electrical

Answer 1

Hint: Photosynthesis is defined as the synthesis of carbohydrates or food from sunlight, water and carbon dioxide by the green plants. It is a kind of endergonic and anabolic process in which the light energy is changed into chemical energy by plants.
During the process of photosynthesis photooxidation of water occurs.

Complete answer:
At the time of the light reaction, light is trapped by photosynthetic pigments present in the quantasomes of grana thylakoids. The light- harvesting complexes are composed of hundreds of pigments bounded by proteins.
Each photosystem possesses a different reaction centre that is made up of a special chlorophyll-a molecule. It also possesses hundreds of other pigment molecules that make up the light-harvesting system called antennae which absorb light of shorter wavelengths to make the photosynthesis more efficient.
Now let us find solution from given options:
A)Light : Splitting of water molecules is called as photo oxidation and it takes place by trapping the light energy provided by sun
B)Chemical : During the splitting light energy is used which is converted into chemical energy and it is released in the form of ATP.
C)Mechanical : It is defined as the sum total of kinetic and potential energy and not needed here.
D)Electrical : Photo oxidation occurs naturally and not with help of electricity.

Hence, the correct answer is option (A)

Note: The process of photosynthesis shows presence of two phases- light phase and the dark phase. The light phase comprises of steps like absorption of light, splitting of water, the release of oxygen and the formation of high energy chemical intermediates i.e. ATP and NADPH. Dark phase makes utilisation of the products of light reaction for carbon fixation.