Photosynthesis and Respiration PDF

Photosynthesis & Respiration Products of photosynthesis- glucose & oxygen Photosynthesis occurs in chloroplast Respiration occurs in mitochondria Autotrophs - Self-feeder - Uses CO2 as main source of carbon - photosynthesis Heterotroph - Can't manufacture their own food...

Photosynthesis & Respiration Products of photosynthesis- glucose & oxygen Photosynthesis occurs in chloroplast Respiration occurs in mitochondria Autotrophs - Self-feeder - Uses CO2 as main source of carbon - photosynthesis Heterotroph - Can't manufacture their own food - They consume other organisms as carbon source Chloroplast -stoma - Thylakoids What is photosynthesis? - It is the process of converting light energy to chemical energy in the form of reduced carbon compounds. 6CO2 + 6H2O C6H12O6+6O2 Reactants light Products Light dependent - Light reaction Chlorophyll absorbs solar energy - Energy (ATP) Light Independent - Calvin Cycle  Car bon fixation by RuBP- carbon dioxide binds with RuBP, 6 carbon compounds, 2 three carbon molecules, 3 PGA used for the formation of glucose Glucose synthesis (6-carbon) Regeneration of RuBP ATP & NADPH used as source of energy - Sugars - Dark 1. Phosphorylated compounds are often involved in metabolism because phosphorylated versions of sugar are more reactive 2. Reduced carbon compounds are shuffled around to generate the compound required for a specific purpose. Factors affecting rate of photosynthesis 1. Light quality (wavelength) Plant pigments − Chlorophyll a, capture most energy − Chlorophyll b − Carotenoids Artificial light 2. Light intensity Photosynthetic Photon flux (PPF)- more intense light Affects plant growth by influencing rate of photosynthetic activity 3. CO2 concentrations Increasing CO2 concentrations increases rate of photosynthesis Commercial applications- greenhouse grown crops such as carnations Practices that improve CO2 availability: wind machines, organic matter to soil 4. Temperature Very high temps- stomates close to conserve water, reduced photosynthetic rate 5. Water Availability Drought leads to closing of stomates Water needed in light reaction in photosynthesis  If there is too much water then, the anaerobic condition around the roots causes a reduction in photosynthesis. 6. Plant development The growth of the plant affects the rate of photosynthesis, both in single leaves and in the total leaf canopy. Source- mature leaf Sink- juvenile leaf, needs carbohydrates for growth Other sinks- roots, fruits, seeds, stems 7. Plant Photosynthetic mechanisms C3- 90% of plant species, Moderate light intensity & Temp - CO2 that enters the leaf is used to generate PGPA (3- carbon phosphoglycerate) - Rice, wheat, potatoes C4- warmer & dryer conditions - Corn, sugarcane, sorghum - Co2 is attached to a 3-carbon organic acid, making a 4-carbon organic acid (OAA) oxaloacetic acid CAM (Crassulacean acid Metabolism)- warmer & drier conditions, deserts - Desert plants, orchids, pineapple, & jade plant. C3 plants Hot, sunny day - Stomates close - CO2 levels drop - O2 levels increase - Add O2 to RuBP Results Forms hydrogen peroxide which is toxic Minimize energy Salvage oxygenated RuBP CAM (Crassulacean acid metabolism) Stomates can open that happens during the night. Respiration C6H12O6 + 6O2 +36ADP + 36PO3 3- 6CO2 + 6H2O + 36ATP 3 steps 1. Glycolysis - Where glucose is broken down - Occurs in cytoplasm 2. Krebs Cycle - Citric acid cycle - Occurs in mitochondria - Completes oxidation of PA to CO2 3. Electron transport - Cyclic reactions - Occurs in cristae Light compensation point- Light intensity at which photosynthesis & respiration rates are equal Ps=Rs Anaerobic respiration (Fermentation) - Anaerobic: oxygen is deficient - Input: Pyruvate (PA) - Output: Ethanol (Plants) or lactic acids (animals)