All organisms need energy to survive, sustain, and grow. That much we already know. We get this energy by consuming food. Thus, food is the primary source of energy for us. When we (humans) are hungry, we make food, using vegetables, meat, dairy products and so on. When animals are hungry, they eat plants (if they’re herbivores) or other animals (if they’re carnivores). So what’s food for plants? They must need some form of energy to survive, sustain and grow, right?
How Plants make Food and Energy?
Well, the answer is photosynthesis. The word can be split into two terms “photos”, meaning “light”, and “synthesis”, meaning “putting together”. So light is used to create something (energy for plants). Think of it as the procedure plants follow to make their food. In a nutshell, photosynthesis is a process in which the energy from the sun is used to produce glucose from carbon dioxide and water. This glucose is then used up as energy by the plant, and in doing so, oxygen is released as a byproduct.
What is the Process of Photosynthesis?
Collection of Ingredients –
- Plants absorb energy from the sun, with the help of a pigment called “chlorophyll”, which is present in their leaves. This is also the pigment that gives leaves its green color.
- Plants absorb water and other minerals from the soil with the help of their roots.
- Plants also absorb CO2 from the air, with the help of “stomata”, which are pores in the leaves.
- All these ingredients are taken to the leaves, the “cooking central”, i.e. the leaves.
The Chemical Reaction –
Once all the necessary ingredients are collected, a chemical reaction takes place in the leaves of the plant.
- The energy from the sun is used to split water molecules into Hydrogen and oxygen molecules
- The hydrogen and carbon di oxide combine to form glucose, which acts as food for plants.
- Oxygen is released as a byproduct, for other organisms to use.
Equation of Photosynthesis
Thus, photosynthesis can be represented as –
Carbon dioxide + water light energy glucose + oxygen
If you wanted a more chemical representation of photosynthesis, this is the equation for it–
6CO2 + 6H20 light energy C6H12O6 + 6O2
That’s the short and sweet version of how plants cook. However, the entire process of photosynthesis doesn’t require light. Only certain stages require the presence of sunlight. Thus, photosynthesis takes place in two broad stages – The light dependent reaction and the light independent reaction. Let’s take a quick look at what these are:
1. The Light Dependent Reaction
You guessed it, this is the stage where the sun’s energy is trapped by the chlorophyll pigment. What happens next is that this energy is converted into a more usable form of energy storage molecule called ATP, and an electron donor/carrier molecule called NADPH. These molecules are needed for the next stage, i.e. the light independent stage.
2. The Light Independent Reaction
The ATP and NADPH molecules created in the previous stage are used up here to produce glucose energy for plants. Specifically, ATP provides energy for the reaction, while NADPH covers the loss of electrons in the glucose forming process.
Did you know? It’s not just plants that use photosynthesis to make their own food. Certain bacteria and algae also use photosynthesis to make food.