What Is The Role Of Light In Photosynthesis

What is the role of light in photosynthesis?

What Is The Role Of Light In Photosynthesis? Lets dive into the article.

Sun gives off energy in the form of electromagnetic radiations consisting of the infrared, visible and ultraviolet spectrum. During a clear day when the sun is not blocked by clouds, sunlight energy is quite obvious otherwise it becomes scattered and diffused. It takes about 8 minutes and 20 seconds for sunlight to reach the surface of the earth from the sun.

Without sunlight earth would only be a ball of ice with no existence of plants and animal species because the normal human body requires a particular temperature to maintain its homeostasis and normal body functioning, in the same way, plants need sunlight to carry out a process called as photosynthesis. 

What Is The Role Of Light In Photosynthesis?


 Plants convert water and carbon dioxide into energy required for carrying normal functions in the presence of sunlight through a process called photosynthesis.

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Key components in photosynthesis:

  1. Sunlight
  2. Chloroplast
  3. Chlorophyll
  4. Water
  5. Carbon dioxide

We have already discussed sunlight, now we will proceed towards the other main components necessary in the process of photosynthesis.

 Chloroplast: chloroplasts are the numerous small organelles present in the leaves containing a synthetic pigment (chlorophyll) responsible for capturing sunlight and converting it to energy which is used by plants.

 Chlorophyll: Chlorophyll is a green synthetic pigment found in chloroplast having four types a, b, c, and d which helps to capture sunlight.

Water: plants absorb water through their roots which combines with six molecules of carbon dioxide to form glucose (which provides energy to plants)

 Carbon dioxide: carbon dioxide has the same importance as water in the process of photosynthesis to form glucose.

Now the main question arises how sunlight is important for photosynthesis? 

The role of sunlight is as important for photosynthesis as the role of oxygen for the survival of human beings.

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P680 and p700:

 There are special dimmers calledp680 and p700 which are responsible for absorbing light of different wavelengths, p680 can absorb light of wavelength 680nm and p700 can absorb light of wavelength 700 nm, they both are found in photo systems.

 Role of p680 and p700:

 P680 and p700 act as natural oxidizer and reducer respectively; electrons are taken away from a molecule by oxidizers while reducers can add an electron to a molecule. P680 and p700 are charged up when they are hit by sunlight. With the help of a manganese molecule when an electron is taken by p680, a chain reaction is set which leads to the production of ATP.

 NADP is reduced by NADPH with the help of an iron molecule when electrons are released by p700. All these reactions are very complicated to understand but the main point here is that sunlight has the main role to charge up those dimmers (p680 and p700) exciting another chain reaction which leads to the synthesis of glucose molecule responsible for providing energy to plants.

 Role of chlorophyll in capturing sunlight:

 Have you ever noticed why plants look green, the answer lies in the fact that green light is reflected from plants while red and green light is absorbed by plants that’s why they appear green? Chlorophyll a and chlorophyll b are responsible for capturing the light.

Chlorophyll is present in the small organelles having piles of thylakoids placed above one another; chlorophyll a can absorb various light spectrums including violet blue red and orange lights while chlorophyll b can usually absorb light ranging in the blue spectrum.

Equation for photosynthesis

  6Water + 6carbon dioxide = glucose + 6oxygen  

This equation indicates that six molecules of water combined with 6 molecules of carbon dioxide giving rise to one molecule of glucose and six molecules of oxygen. Oxygen released by plants in the day time is consumed by human beings and animals to remain alive.


 Hence after our thorough discussion, we can conclude that sunlight has a very major role in photosynthesis (a process involving utilization of water and carbon dioxide and their conversion into energy and oxygen in the presence of sunlight) with the help of chlorophyll, a photosynthetic pigment present in chloroplast responsible for capturing different electromagnetic spectrums of light.

P680 and p700 act as dimmers to speed up the process of photosynthesis by giving and taking up the electrons liberating oxygen and energy. Humans and animals release carbon dioxide as a byproduct of cellular respiration, this carbon dioxide with water helps to form a molecule of glucose and oxygen, this oxygen are required by living things to remain alive, therefore a cycle continues. Therefore the role of light is very important in all this process.

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