Photosynthesis | quick revision for NEET
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| Photo By Ai |
- Photosynthesis Overview:
- Vital biological process in which plants, algae, and some bacteria convert light energy into chemical energy.
- Occurs in chloroplasts, specialized organelles containing chlorophyll pigments.
-Key Steps of Photosynthesis:
- Light Reactions:
- Light energy is absorbed by chlorophyll in the thylakoid membranes of chloroplasts.
- Water molecules are split (photolysis) into oxygen, protons (H+), and electrons.
- Electrons are energized and transferred along the electron transport chain, generating ATP and NADPH.
-Calvin Cycle (Dark Reactions):
- ATP and NADPH from the light reactions are used to convert carbon dioxide (CO2) into organic molecules, such as glucose.
- Carbon fixation occurs as CO2 is combined with ribulose bisphosphate (RuBP) to form 3-phosphoglycerate (3-PGA).
- 3-PGA is reduced to glyceraldehyde-3-phosphate (G3P) using ATP and NADPH, which can be used to synthesize glucose and other carbohydrates.
- Regeneration of RuBP allows the cycle to continue.
-Factors Affecting Photosynthesis:
- Light Intensity:
- Increased light intensity generally leads to higher rates of photosynthesis until a saturation point is reached.
-Carbon Dioxide (CO2) Concentration:
- Elevated CO2 levels can enhance photosynthetic rates, as CO2 is a substrate for the Calvin cycle.
-Temperature:
- Optimal temperatures promote enzyme activity and photosynthesis, but extreme temperatures can denature enzymes and inhibit the process.
-Water Availability:
- Adequate water is essential for maintaining turgor pressure, facilitating nutrient uptake, and participating in the light reactions.
- Nutrient Availability:
- Essential nutrients such as nitrogen, phosphorus, and potassium are required for chlorophyll synthesis and enzyme function.
-Photosynthetic Pigments:
- Chlorophyll: Absorbs primarily blue and red wavelengths of light, reflecting green light and giving plants their green color.
- Carotenoids: Accessory pigments that absorb blue and green light, enhancing light absorption and protecting chlorophyll from damage.
- Photosynthesis and Oxygen Production:
- Oxygen (O2) is released as a byproduct of the light reactions during the splitting of water molecules.
- This oxygen is vital for aerobic respiration in plants and other organisms, providing the necessary substrate for cellular energy production.
-Importance of Photosynthesis:
- Food Production:
- Primary source of organic compounds for plants and the foundation of the food chain, supporting heterotrophic organisms.
- Oxygen Production:
- Generates oxygen as a byproduct, contributing to atmospheric oxygen levels crucial for aerobic organisms.
- Carbon Sequestration:
- Removes carbon dioxide from the atmosphere, mitigating climate change by storing carbon in plant biomass and soil.
Photosynthesis is a fundamental process that sustains life on Earth by harnessing solar energy to produce food, oxygen, and organic compounds essential for ecosystem functioning and biodiversity. Understanding its mechanisms and environmental factors is crucial for optimizing agricultural productivity, ecological conservation, and sustainable resource management.