Cracking NEET? Ace Photosynthesis! Your ultimate short notes on photosynthesis for NEET prep are right here. Master key concepts, score higher, and conquer NEET. This guide provides concise, NEET-focused notes on photosynthesis in higher plants.
What is Photosynthesis & its Importance?
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. The overall equation is simple: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂. This means six molecules of carbon dioxide and six molecules of water react in sunlight to produce one molecule of glucose (a sugar) and six molecules of oxygen.
Photosynthesis is incredibly important. It’s the foundation of most food chains, providing energy for almost all life on Earth. Plants, as primary producers, convert solar energy into chemical energy stored in glucose. This energy supports the herbivores which in turn support carnivores and omnivores. It also releases oxygen, essential for aerobic respiration in most living organisms.
There are three main types of photosynthesis: C3, C4, and CAM. We’ll delve deeper into their differences later.
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Light-Dependent Reactions: The Energy Capture Phase
The light-dependent reactions occur in the thylakoid membranes within chloroplasts. Here, light energy is captured by chlorophyll and other pigments located within photosystems I and II. This photoexcitation process excites electrons, initiating an electron transport chain.
As electrons move down this chain, energy is released, used to pump protons (H⁺ ions) across the membrane, creating a proton gradient. This gradient drives ATP synthesis through chemiosmosis, a vital process that involves ATP synthase, a significant enzyme. Simultaneously, NADP⁺ is reduced to NADPH, another crucial electron carrier used in later stages.
Light-Independent Reactions: The Carbon Fixation Phase
The light-independent reactions, also known as the Calvin cycle, take place in the stroma of the chloroplast. This stage uses the ATP and NADPH produced during the light-dependent reactions to convert carbon dioxide into glucose.
The process begins with carbon fixation where a molecule of CO₂ is catalyzed with Ribulose-1,5-bisphosphate (RuBP) by the enzyme RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) the most abundant protein in the world. This proceeds the fixation of inorganic matter using that RuBisCO converts this gaseous organic product. Formation of G3P or glyceraldehyde-3-phosphate occurs through a redox cycle facilitated specifically involved in light dependent actions are synthesized through complex chain of events involving ATP NADPH etc. Several molecules of G3P combine to form glucose and later other carbohydrate molecules that ultimately synthesize glucose
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Factors Affecting Photosynthesis
Several environmental factors influence the rate of photosynthesis:
- Light intensity: Increased light intensity boosts efficiency initially; further rise eventually becomes saturated depending depending as all chlorophyll molecules become activated, eventually plateauing.
- Light quality: Light quality which includes intensity and wavelength too play also plays a significant affect. Chlorophyll a readily utilizes photosynthetically active red wavelength radiation predominantly whilst chlorophyll b performs comparatively lower under other conditions
- Light duration: Photoperiodism – the response in organisms to a relative change length related phenomenon in length – influences duration greatly. Short-day will exhibit limited photosynthetic outcomes; lengthy exposures give rise longer and heightened photosynthesis productivity accordingly.
- CO₂ concentration: Elevated Co2 generally correlates in improvement with increased photosynthesis until achieving a maximum equilibrium, much likewise effect analogous to what follows. Limiting factor applies when low in conc when reaching a plateau under higher co2 amounts eventually
- Temperature: An optimal range exists because enzyme functions are temperature sensitive. Temperatures rising or falling above optimal temperatures result result decreased rates
- Water availability: Water scarcity leads to water stress reducing photosynthesis. Stomata close preventing Co2 entry yet preserving water balance; simultaneously impairing CO2- fixation hence hindering productivity substantially.
- Mineral nutrients: Nutrients like magnesium (a crucial component of chlorophyll) and nitrogen impact protein synthesis with directly influenced photosynthetic rate; their overall deficient states limit it overall .
Photosynthesis vs. Respiration: Key Differences
Photosynthesis and respiration are complimentary processes crucial for survival and function in vascular plants. Although seemingly mirror processes at the macroscopic scale. fundamental discrepancies exists at the cellular level requiring critical study examination. Major comparisons:
Process: |Photosynthesis| respiration
—|—|—
Overall: Building carbohydrates From light|Breaking down carb use in cell func Respiration |Energy release|
Location |Chloroplast |Mitochondria
Raw Material | CO2, H20 , Light |carbohydrate/ATP| O2
Both processes have distinct but equally significant roles within the plant realm and in total ecological equilibrium overall. Understanding each interplay helps in thorough understanding fully plant physiological responses which require precise scrutiny.
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C3, C4, and CAM Plants: A Comparison
In C3 or Hatch-Slack pathway CO which involves one carbon carbon atoms during synthesis process directly through Rubisco whilst fixing through reactions whereas this enzyme takes central prominence within C3.
C4 plants (e.g., maize, sugarcane ) incorporate a special enzyme initial molecule involved. These plants spatially minimize photorespiration effects whereas in CAM plants plants such species like cactus crassulacean acid metabolism involves CO2 fixation that happens mainly during later night timing hours. These distinctions reflect environmental implications where species inhabit adapted systems accordingly accordingly
FAQ
What is the role of chlorophyll in photosynthesis? Chlorophyll is the primary pigment capturing light energy, initiating the light-dependent reaction phase. This absorption makes possible converting radiant into stored chemical form and vital components later photosynthesis itself .
How do C4 plants overcome photorespiration? C4 plants spatially avoid photorespiration by fixing CO2 initially to yield various compounds with four-carbon (four carbons specifically)., concentrating this nearby Rubisco’s within bundle. The Rubisco-containing cells avoid oxygen’s entry that compete for co2 hence avoiding oxygen molecules that prevent it significantly. , maximizing CO2 use efficacy ultimately , resulting enhancement of efficiency significantly.
What are the products of photosynthesis? Besides essential chemical substances for synthesis such glucose that forms major final main sugar, oxygen released significantly too. Subsequently glucose facilitates biosynthesis across variety molecules vital cellular functional performance at molecular levels
How does light intensity affect the rate of photosynthesis? Photosynthesis typically increases with greater amount until plateau reaches maximum potential . Below limits there exist a lower limit while above there occurs limit a peak production capability at certain level with reduced responses subsequently
What are the differences between light-dependent and light-independent reactions? Light-dependent reactions harnesses light energy to subsequently synthesize ATP, while light-independent events use ATP made already plus the additional NADH formed directly to incorporate inorganic carbon within organic products yielding eventually molecules capable support subsequent functions inside cells
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CONCLUSION
Mastered the basics of photosynthesis for NEET? Congratulations on understanding complex cellular reactions ! Share this with your fellow NEET aspirants! Leave a comment below if you have any questions.
