Digestive System & Photosynthesis PDF

# DIGESTIVE SYSTEM ## 1. Role of Digestive Organs - **Mouth:** Mechanical digestion (chewing) and chemical digestion (saliva containing amylase breaks down starch). - **Stomach:** Produces gastric juices (acid and enzymes like pepsin) to break down proteins and churn food into chyme. - **Small Int...

# DIGESTIVE SYSTEM ## 1. Role of Digestive Organs - **Mouth:** Mechanical digestion (chewing) and chemical digestion (saliva containing amylase breaks down starch). - **Stomach:** Produces gastric juices (acid and enzymes like 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 from the 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 aid in their digestion in the small intestine. - **Gallbladder:** Stores bile produced by the liver and releases it into the small intestine to help digest fats. - **Rectum and Anus:** Store and expel waste from the body through defecation. ## 2. Enzymes Involved in Digestion - **Amylase:** Breaks down starch into sugars (active in mouth 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 - **Carbohydrates:** Broken down by amylase (mouth) and other enzymes (small intestine) into monosaccharides (e.g., glucose). - **Cellulose/Fiber:** Not digested by human enzymes; it aids 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) into fatty acids and glycerol. ## 4. Body Position and Pill Intake Body 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) - **Proteases:** Enzymes that break down proteins. - **Lab Observations:** Proteases were likely found in the stomach samples, where protein digestion occurs. Data could be collected by testing protein breakdown using specific indicators like biuret solution. # PHOTOSYNTHESIS ## 1. Leaf Structure & Function - **Cuticle:** Waxy layer that reduces water loss. - **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 reduce water loss. - **In Wet Environments:** More stomata for better gas exchange. ## 3. Light Absorption - **Light:** 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 $6CO_2 + 6H_2O + sunlight -> C_6H_{12}O_6 + 6O_2$ ## 5. Light-Dependent and Light-Independent Reactions - **Light-Dependent Reactions:** Occur in the thylakoid membranes of the chloroplasts. Water is split to release oxygen, and light energy is converted into ATP and NADPH. - **Light-Independent Reactions (Calvin Cycle):** Occur in the stroma. ATP and NADPH produced in the light-dependent reactions are used to convert CO2 into glucose. ## 6. Chloroplast Structure - **Outer Membrane:** Encloses the chloroplast. - **Inner Membrane:** Surrounds the stroma. - **Thylakoids:** Membranous sacs where light-dependent reactions occur. - **Stroma:** Fluid where the Calvin cycle occurs.