Digestive System & Photosynthesis PDF
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This document provides notes on the processes of digestion, including the role of digestive organs and involved enzymes. Furthermore, the document covers the process of photosynthesis, focusing on light-dependent and light-independent reactions, and the relevant leaf structure and adaptations. It also touches on cellular respiration and the equation for cellular respiration.
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DIGESTIVE SYSTEM 1. Role of Digestive Organs M outh: Mechanical digestion (chewing) and chemicaldigestion (saliva containing amylase breaks down starch). Stomach: Produces gastric juices (acid and enzymeslike pepsin) to break down...
DIGESTIVE SYSTEM 1. Role of Digestive Organs M outh: Mechanical digestion (chewing) and chemicaldigestion (saliva containing amylase breaks down starch). Stomach: Produces gastric juices (acid and enzymeslike pepsin) to break down proteins and churn food into chyme. Small Intestine: Major site of digestion and absorption.Enzymes (amylase, protease, lipase) break down carbs, proteins, and lipids, respectively. Nutrients are absorbed into the bloodstream via villi. Large Intestine: Absorbs water and electrolytes fromthe remaining indigestible food matter. Forms and stores feces. Pancreas: Produces digestive enzymes (amylase, lipase,protease) and bicarbonate to neutralize stomach acid. Liver: Produces bile, which emulsifies fats to aidin their digestion in the small intestine. Gallbladder: Stores bile produced by the liver andreleases it into the small intestine to help digest fats. Rectum and Anus: Store and expel waste from the bodythrough defecation. 2. Enzymes Involved in Digestion A mylase: Breaks down starch into sugars (active inmouth and small intestine). Protease (e.g., Pepsin): Breaks down proteins into amino acids (active in the stomach). Lipase: Breaks down fats (lipids) into fatty acids and glycerol (active in the small intestine). Lactase: Breaks down lactose into glucose and galactose (active in the small intestine). Nuclease: Breaks down nucleic acids into nucleotides (active in the small intestine). 3. Digestion of Different Molecules C arbohydrates: Broken down by amylase (mouth) andother enzymes (small intestine) into monosaccharides (e.g., glucose). Cellulose/Fiber: Not digested by human enzymes; itaids in digestion by adding bulk to stool and aiding peristalsis. Proteins: Broken down by proteases (stomach - pepsin,small intestine - trypsin and chymotrypsin) into amino acids. Lipids: Broken down by lipase (small intestine) intofatty acids and glycerol. 4. Body Position and Pill Intake B ody position affects how pills are ingested and absorbed. For example, swallowing pills while sitting upright ensures they pass through the esophagus and stomach efficiently. Lying down immediately after could delay absorption. 5. Proteases in Digestion (Lab Review) P roteases: Enzymes that break down proteins. Lab Observations: Proteases were likely found in thestomach samples, where protein digestion occurs. Data could be collected by testing protein breakdown using specific indicators like biuret solution. PHOTOSYNTHESIS 1. Leaf Structure & Function uticle: Waxy layer that reduces water loss. C Epidermis: Protective outer layer. Stomata: Pores for gas exchange (CO₂ in, O₂ out). Mesophyll: Contains chloroplasts for photosynthesis. Xylem & Phloem: Transport water and nutrients (xylem)and sugars (phloem). 2. Stomata Adaptations In Dry Environments: Fewer or smaller stomata to reducewater loss. In Wet Environments: More stomata for better gas exchange. 3. Light Absorption L ight: Plants absorb light in the visible spectrum,primarily blue (430-450 nm) and red (640-680 nm) light. Green light is reflected, making plants appear green. 4. Photosynthesis Equation 6CO2 + 6H2 O + sunlight -> C6 H12 O6 + 6O2. 5. Light-Dependent and Light-Independent Reactions L ight-Dependent Reactions: Occur in the thylakoidmembranes of the chloroplasts. Water is split to release oxygen, and light energy is converted into ATP and NADPH. Light-Independent Reactions (Calvin Cycle): Occurin the stroma. ATP and NADPH produced in the light-dependent reactions are used to convert CO₂ into glucose. 6. Chloroplast Structure uter Membrane: Encloses the chloroplast. O Inner Membrane: Surrounds the stroma. Thylakoids: Membranous sacs where light-dependentreactions occur. Stroma: Fluid where the Calvin cycle occurs. 7. Lab Activities S tomata Lab: Investigated how environmental conditions(e.g., light) affect stomatal density. Chromatography Lab: Separated plant pigments to demonstratethat different pigments absorb light at different wavelengths. CELLULAR RESPIRATION 1. Cellular Respiration Equation C6H12O6 + 6O2 → 6CO2 + 6H2O + energy 2. Aerobic vs Anaerobic Respiration A erobic Respiration: Requires oxygen and occurs inthe mitochondria. It includes glycolysis(in the cytoplasm),Krebs cycle, andETC(electron transport chain). Produces 36-38 ATP. Anaerobic Respiration (Fermentation): Occurs withoutoxygen, produces 2 ATP, and results in byproducts likelactic acid(in muscles)orethanol and CO₂(in yeast). . Measuring Anaerobic Respiration: In the muscle fatigue lab, lactic acid buildup was 3 observed as a byproduct of anaerobic respiration when oxygen was insufficient. 4. Mitochondrial Structure Inner Membrane: Contains proteins for the ETC andATP synthesis. Outer Membrane: Separates mitochondrion from the cytoplasm. Matrix: Contains enzymes for the Krebs cycle. Intermembrane Space: Where protons accumulate in theETC. . Cyanide and Cellular Respiration: Cyanide inhibits cytochrome c oxidase, a key 5 enzyme in the ETC, blocking ATP production and causing cell death. FOOD CHAINS & WEBS . Energy Transfer: Energy is transferred from producers (plants) to primary consumers 1 (herbivores), secondary consumers (carnivores), and so on. Only about 10% of energy is transferred to each successive trophic level. 2. Organism Classification: Autotrophs: Organisms that make their own food (e.g., plants). eterotrophs: Organisms that consume other organisms (e.g., animals). H Herbivores: Primary consumers, eat plants. Carnivores: Secondary/tertiary consumers, eat otheranimals. Omnivores: Eat both plants and animals. Decomposers: Break down dead organisms and recyclenutrients (e.g., bacteria, fungi). . Role of Cellular Respiration and Digestion in Energy Flow: Cellular respiration breaks 3 down food (organic matter) into usable energy (ATP), which supports life processes. Digestion prepares food for absorption and energy release. BIOGEOCHEMICAL CYCLES 1. Carbon Cycle W hy Plants & Animals Need Carbon: Carbon is a fundamentalcomponent of organic molecules. Carbon in the Atmosphere: Carbon is added throughprocesses like respiration, combustion (burning of fossil fuels), and volcanic eruptions. It is removed through photosynthesis. Fossil Fuels: Formed from the remains of dead organismsunder pressure over millions of years. Burning fossil fuels releases CO₂ into the atmosphere. Ocean Acidification: Increased CO₂ levels in the atmosphereare absorbed by oceans, leading to more acidic conditions, which harm marine life. Photosynthesis & Respiration: These processes areinterconnected: photosynthesis removes CO₂ from the atmosphere, and respiration releases it. 2. Nitrogen Cycle W hy Plants & Animals Need Nitrogen: Nitrogen is akey component of amino acids and proteins. Largest Reservoir: The atmosphere (78% nitrogen gas). Nitrogen-Fixing Organisms: Bacteria (e.g., Rhizobium)convert nitrogen gas into forms plants can use (e.g., ammonium). 3. Water Cycle W hy Plants & Animals Need Water: Water is essentialfor all life processes. Largest Reservoir: Oceans. Water Movement: Evaporation (water vapor rises), transpiration(plants release water vapor), condensation (water vapor cools and forms clouds), and precipitation (rain, snow). 4. Phosphorus Cycle W hy Plants & Animals Need Phosphorus: Phosphorus is important for DNA, RNA, and ATP. Largest Reservoir: Rocks and soil. Eutrophication: Excess phosphorus from fertilizersleads to overgrowth of algae in water bodies, depleting oxygen and harming aquatic life.
