What is a matter transformation and energy transformation in photosynthesis?

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gsenviro's profile pic

gsenviro | College Teacher | (Level 1) Educator Emeritus

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Photosynthesis is the process by which plants convert carbon dioxide and water into glucose and oxygen in the presence of sunlight. The balanced chemical reaction for this process can be written as:

`6CO_2 (g) + 6H_2O (aq) + sunlight -> C_6H_12O_6 (s) + 6O_2 (g)`

There are different phases (or states) of matter, such as solid, liquid, gas and plasma. Photosynthesis represents the consumption of some reactants and production of some products, during which phase transformations take place. For example, carbon dioxide is in the gas phase and water is in the liquid or aqueous phase, while glucose is in its solid phase and oxygen is in its gas phase. Photosynthesis involves matter transforming into entirely new molecules in different physical states.

This process also involves energy transformations. Photosynthesis uses the light energy of the sun and converts it to chemical energy (stored in glucose molecules). The chemical energy of glucose is converted to ATP molecules during the process of cellular respiration and is then used by organisms. 

Thus, photosynthesis involves both matter and energy transformations. 

Hope this helps. 

llltkl's profile pic

llltkl | College Teacher | (Level 3) Valedictorian

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In photosynthesis, organic carbon containing substances (carbohydrates or sugars) are generated from carbon dioxide and water. Oxygen is also produced as a by-product. This constitutes the total matter transformation is photosynthesis.

Light energy transforms into chemical potential energy, through a very efficient biotransformation process – this is energy transformation. About 0.05% of the total `10^22` kJ energy which reaches the earth every year from the sun is assimilated by photosynthesis. This is the general energetic pool for all living processes of the earth.

On a more detailed note, photosynthesis can be considered as a reaction during which water is split, driven by the energy of photons, producing O_2 and transferring hydrogen to the redox system NADPH/NADP^+, the nicotinamide adenine dinucleotide phosphate. Simultaneously a proton gradient across the thylakoid membrane is generated (Thylakoids are building blocks of chloroplasts). In a separate process, this leads to the synthesis of ATP, the energy coin. Subsequently, an ATP-consuming synthesis of carbohydrates occurs. This process is usually called the dark reaction of photosynthesis occurring in the stroma of chloroplasts. The process of photosynthesis can be represented roughly by the following scheme:

`6CO_2 + 6H_2O stackrel (hnu)(rarr) C_6H_12O_6 + 6O_2`

This process is characterized by a standard free Gibbs’ energy of reaction, `DeltaG^o` =2868 kJ/mole, made possible only with greater input energy from light and by very efficient catalysis of chlorophylls.