Definitely, you have learned about photosynthesis in your school. It is the process by which green plants produce oxygen and glucose using sunlight and water. Plants have been performing photosynthesis for millions of years, making life possible on Earth. Had photosynthesis not been there, the diverse flora and fauna could not have existed. All living organisms except certain micro bacteria require oxygen to survive. Oxygen is one of the three end products of photosynthesis. Continue reading to know more about it.
1. What is Photosynthesis? Explain the Definition, Process & Diagram in Brief
This is the process by which living plant cells produce oxygen and food substances through chlorophyll. These food substances are glucose and starch, made from water and carbon dioxide using light energy. The end products of photosynthesis occur in two stages:
A. Light Reaction
It happens in the thylakoids in the presence of sunlight. This reaction is called a photochemical reaction, as it occurs in the presence of photons. The chlorophyll that’s present in the thylakoids absorbs photons. The energy derived from photons raises the energy level of electrons. This energy causes the photolysis of water. The H2O electrons get divided into H+ and OH− ions.
- 4H₂O → 4H⁺ + 4(OH)⁻
- 4(OH)⁻ → 2H₂O + O₂ + 4e⁻
- On adding the above formulae, you get: 2H₂O → 4H⁺ + O₂ + 4e⁻
Nicotinamide adenine dinucleotide phosphate (NADP) gets reduced in the next part of the reaction, forming NADP hydrogen due to excess free electrons.
- 2NADP + 4e⁻ + 4H⁺ → NADPH
Next, photophosphorylation takes place. In the presence of sunlight, free electrons convert adenosine diphosphate into energy-rich adenosine triphosphate by adding inorganic phosphate. (See What Would Happen if There was No Sunlight?)
B. Dark Reaction
This reaction occurs in the stroma and is called dark because it does not need photons. The dark reaction occurs simultaneously with the light reaction; the gap between these reactions is less than a thousandth second. In this reaction, ATP and NADPH reduce or assimilate carbon dioxide into glucose (C6H12O6).
Ribulose bisphosphate changes inorganic carbon, i.e., one 5-carbon molecule (5C) into three-carbon molecules (3C) and 3 phosphoglycerates. Carbon gets synthesized into a glucose molecule using the energy stored in NADPH and ATP. This glucose is either stored in the form of starch or used up. The overall chemical reaction can be expressed as:
- 6CO2 + 6H2O → C6H12O6 + 6O2
2. What is the Importance of Photosynthesis?
The primary importance of photosynthesis is listed below:
- It produces oxygen required for all living organisms to survive. (See What are Examples of Living Things?)
- It maintains a balanced level of O2 and CO2 in the environment.
3. What are the End Products of Photosynthesis? What are Three End Products of Photosynthesis?
Sugar, water, and oxygen are the three end products of photosynthesis. These three products have important usage:
- Glucose is either consumed by the plant or stored in the form of starch. A part of it may be converted into sucrose which is used to synthesize proteins, fats, etc.
- Water is re-utilized in photosynthesis.
- The plant uses oxygen in its respiration, and a large part of it is released into the atmosphere. This oxygen is the most integral part of the sustenance of life on Earth because most creatures depend on oxygen for survival. (See How many valence electrons does oxygen have?)
4. The End Product of Photosynthesis is Sucrose. True or False?
True, in the end, sucrose is one of the end products of photosynthesis. It is also sourced from storage.
5. What are the End Products of Cellular Respiration?
Cellular respiration is the process of breaking down carbohydrates into adenosine triphosphate (ATP) to release energy. This energy in the form of ATP is essential for all cells to carry on with life activities. At each stage of this reaction, in eukaryotic cells, mitochondria work as a catalyst to speed up the reactions. Glucose is then converted into carbon dioxide, adenosine triphosphate, and water. These are the end products of cellular respiration. (See What are Few Examples of Producers Consumers and Decomposers?)
6. What is the End Product of Glycolysis?
Glycolysis occurs in the cytoplasm. In animal cells, glycolysis is a process in which 10 chemical reactions break down glucose into pyruvic acid, the end product. The energy released during the conversion of glucose from fats, proteins, or carbohydrates is stored in the form of adenosine triphosphate (ATP).
The pyruvate molecules thus produced enter the mitochondria, where they are further converted into acetyl coenzyme A. The acetyl coenzyme A later enters the tricarboxylic acid cycle or TCA Cycle. This conversion is called transition reaction or pyruvate oxidation in the process of cellular respiration. (Also read 25 Best Thornless Roses)
