General Biology (EXAM 2) Practice Concepts

Chapter 5: Plasma Membranes Which of the following is not found in plasma membrane? - C. RNA Which of the following transportation requires ATP? - C. Endocytosis Which of the following can cross plasma membrane through simple diffusion? - A. O₂ Which junction allows transportation from cell to cell? - B. Gap Describe the structure of plasma membrane. Identify its major components. - Fluid phospholipid bilayer with embedded proteins, cholesterol, and glycocalyx. Major components: phospholipids, cholesterol, proteins, glycocalyx. What is the function of cholesterol in plasma membrane? - Regulates membrane fluidity: increases fluidity at low temperatures, stiffens membrane at high temperatures. What property of phospholipid makes the membrane a bilayer? - Amphipathic nature (hydrophobic tails face inward; hydrophilic heads face outward). List major functions of proteins in plasma membrane. - Channel/carrier proteins, cell recognition, receptors, enzymatic activity, junctions. Describe the methods of transportation across plasma membrane. Which one requires ATP? Which one needs integral protein? - Passive (simple/facilitated diffusion, osmosis; no ATP) and active (primary/secondary transport, endocytosis/exocytosis; ATP required). Integral proteins are needed for facilitated diffusion and active transport. Name the water channel protein. - Aquaporin. What will happen to a plant or animal cell if placed in isotonic, hypertonic, or hypotonic solution? - Isotonic: no net movement. Hypertonic: cell crenates. Hypotonic: cell swells/lyses. What are the major components of animal extracellular matrix? - Proteoglycans, collagen, fibronectin, elastin. Describe the structure and function of plasmodesmata, tight junction, desmosome, and gap junction. - Plasmodesmata: plant cell channels. Tight junction: seals cells (e.g., intestine). Desmosome: anchors (e.g., skin). Gap junction: allows molecule exchange (e.g., heart). What is the major component of plant cell wall? - Cellulose. Chapter 6: Metabolism Enzyme speeds up reaction by increasing activation energy. - False During muscle contraction, 100% of the energy released from ATP is used to do work. - False When entropy of the universe increases, the universe . - A. is more stable If a reaction’s ΔG is negative, the reaction is . - A. spontaneous Oxidation is . - D. both A & B (loss of e⁻/H) Explain the difference between potential energy and kinetic energy. - Potential energy: stored energy (e.g., chemical bonds). Kinetic energy: energy of motion (e.g., heat). State two energy laws and apply them to energy transformation. - 1st law: Energy cannot be created/destroyed. 2nd law: Energy conversions increase entropy. Define entropy. - Measure of disorder in a system; increases during spontaneous processes. Define metabolism, catabolism, and anabolism. - Metabolism: all chemical reactions. Catabolism: breaks down molecules. Anabolism: builds molecules. Define exergonic reaction and endergonic reaction. - Exergonic: releases energy (ΔG < 0). Endergonic: absorbs energy (ΔG > 0). How does ATP transfer energy to other cellular processes? - ATP hydrolysis releases energy; phosphorylation transfers energy to other molecules. Explain how enzymes speed chemical reactions. - Lower activation energy. What is induced fit? - Enzyme’s active site adjusts shape to better bind the substrate. What is an enzyme made of? - Mostly proteins; some RNA (ribozymes). Define holoenzyme. - Apoenzyme (inactive enzyme) + cofactor = active enzyme. Define active site. - Region of enzyme where substrate binds and reaction occurs. What are the factors affecting the speed of enzymatic reactions? - Substrate concentration, pH, temperature, inhibitors. Explain noncompetitive and competitive inhibition of enzymes. - Competitive: inhibitor competes for active site. Noncompetitive: binds to allosteric site, altering enzyme shape. Define oxidation, reduction, redox. - Oxidation: loss of e⁻/H. Reduction: gain of e⁻/H. Redox: coupled oxidation-reduction reactions. Chapter 7: Cellular Respiration Glycolysis happens in __. - A. cytosol Which is not a product of glycolysis? - B. CO₂ Citric acid cycle happens in . - B. mitochondrion Which is NOT a product of citric acid cycle? - A. Pyruvate Most of the ATP is produced by . - C. ETC Amino acids transfer the amino group to α-ketoglutarate, turning α-ketoglutarate into . - B. glutamate Where in the cell does glycolysis happen? - Cytosol. What are the molecules needed for glycolysis? - Glucose, ATP, NAD⁺. What are the end products of glycolysis? - 2 pyruvate, 2 ATP, 2 NADH. Where in the cell does the preparatory reaction happen? - Mitochondrial matrix. What are the molecules needed for the preparatory reaction? - Pyruvate, CoA, NAD⁺. What are the end products of the preparatory reaction? - Acetyl CoA, CO₂, NADH. Where in the cell does the Krebs cycle happen? - Mitochondrial matrix. What are the molecules needed for the Krebs cycle? - Acetyl CoA, NAD⁺, FAD, ADP. What are the end products of the Krebs cycle? - CO₂, ATP, NADH, FADH₂. Where in the cell does the electron transport chain exist? - Cristae (inner mitochondrial membrane). What are the molecules needed for the electron transport chain? - NADH, FADH₂, O₂. What are the end products of the electron transport chain? - ATP, H₂O. Among the above processes, which produces the most ATP? Which process needs O₂? Which releases CO₂? Which produces H₂O? - Most ATP: ETC. Needs O₂: ETC. Releases CO₂: Krebs/prep reactions. Produces H₂O: ETC. When is fermentation necessary? - When O₂ is absent. Discuss the relationship between glycolysis and fermentation. - Fermentation regenerates NAD⁺ to keep glycolysis running. Does fermentation generate ATP? - No; only glycolysis produces 2 ATP. Why is fermentation necessary for glycolysis when O₂ is absent? - To regenerate NAD⁺ for continued glycolysis. What are the products of alcoholic fermentation? Give an example. - Ethanol and CO₂ (e.g., bread, wine). What are the products of lactate fermentation? Give an example. - Lactate (e.g., yogurt, muscle cells). Describe how fats and proteins can be used for ATP production. - Fats → glycerol (enters glycolysis) and fatty acids (enter Krebs via acetyl CoA). Proteins → amino acids (deaminated to enter Krebs). Chapter 8: Photosynthesis Which of the following cannot photosynthesize? - C. mushroom Where are photosystems located? - B. thylakoid membrane Which is not a product of light reaction? - D. glucose Where does Calvin cycle occur? - C. stroma Calvin cycle is to fix and reduce _____ into G3P. - CO₂ Define photosynthesis. - Process converting CO₂ + H₂O → glucose using sunlight (CO₂ reduced, H₂O oxidized). What organisms are photosynthetic? - Plants, algae, cyanobacteria. Describe the structure of chloroplasts. Do all photosynthetic organisms have chloroplasts? - Chloroplasts: thylakoids (light reactions) and stroma (Calvin cycle). Cyanobacteria use thylakoids, not chloroplasts. What’s the function of chlorophyll in the photosystems? - Absorbs light energy and transfers it to reaction centers. Where do light reactions occur? - Thylakoid membrane. Describe the process of light reactions. - Photosystems II/I absorb light → energize electrons → ETC → ATP/NADPH produced; H₂O splits → O₂ released. What is the ultimate donor of electrons in light reactions? - H₂O. Final recipient: NADP⁺. When is O₂ released and CO₂ absorbed? - O₂ released in light reactions; CO₂ absorbed in Calvin cycle. Where do Calvin cycle reactions occur? - Stroma. Describe the process of Calvin cycle reactions. - CO₂ fixation (RuBP + CO₂ → 3PG), reduction (3PG → G3P), RuBP regeneration. State the importance of G3P. - Precursor for glucose, starch, cellulose, fatty acids, amino acids. Compare and contrast C₃, C₄, and CAM plants. - C₃: standard Calvin cycle (photorespiration in heat). C₄: spatial separation (mesophyll/bundle sheath). CAM: temporal separation (CO₂ fixed at night).