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AP Bio Exam: Unit 2
AP Exam
| Question | Answer |
|---|---|
| How can a cell increase surface area without increasing the volume? | By folding or flattening the membrane, like microvilli. |
| How does an increase in surface area to volume ratio affect the cell? | Increases efficiency of nutrient/waste exchange and heat transfer. |
| Which cell is the most efficient? Justify. | Cell D; it has the highest surface area to volume ratio. |
| What is the function of complex cellular structures like membrane folds on cells? | Increase surface area for transport or metabolic processes. |
| How can an increase in surface area to volume affect heat exchange? | Allows for faster heat loss or gain depending on the environment. |
| What is the relationship between organism size/mass and the rate of heat exchange? | Smaller organisms lose heat faster due to higher surface area to volume ratio. |
| Describe the relationship between metabolic rate per unit body mass and the size of multicellular organisms. | Smaller organisms have a higher mass-specific metabolic rate. |
| What are the components of the cell membrane? | Phospholipids, proteins, cholesterol, and carbohydrates. |
| How do each of the above components function in the cell membrane? | Phospholipids form the barrier; proteins transport; cholesterol stabilizes; carbs identify. |
| Describe the orientation of the components for the structure of the phospholipid. | Hydrophilic heads face outward; hydrophobic tails face inward. |
| Based on aqueous internal and external conditions, how would the phospholipid molecules be oriented? | Heads face water on both sides; tails cluster in the middle. |
| How does the phospholipid bilayer maintain the internal environment of a cell? | Acts as a selective barrier regulating entry and exit of substances. |
| What are the different types of membrane proteins? | Integral, peripheral, and transmembrane proteins. |
| Describe six functions of membrane proteins. | Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton. |
| What makes a protein hydrophilic or hydrophobic? | Interaction with water; polar regions are hydrophilic, nonpolar are hydrophobic. |
| How does the polarity of the membrane protein affect its orientation in the membrane? | Hydrophobic regions embed in the bilayer; hydrophilic regions face the aqueous environment. |
| Where would you find hydrophilic regions of the proteins? | Exposed to the internal or external aqueous environments. |
| Where would you find hydrophobic regions of the proteins? | Embedded within the phospholipid bilayer. |
| What are the components that make up the plasma membrane? | Phospholipid bilayer, proteins, cholesterol, glycoproteins, and glycolipids. |
| What is the function of steroids in the plasma membrane? | Cholesterol modulates membrane fluidity and stability. |
| What is the function of glycoproteins in the plasma membrane? | Cell-cell recognition and signaling. |
| What is the function of glycolipids in the plasma membrane? | Cell-cell recognition and maintaining membrane stability. |
| Define the fluid mosaic model. | The membrane is a fluid structure with a mosaic of various proteins embedded in it. |
| What is the function of the plasma membrane? | Regulates what enters and exits the cell; maintains homeostasis. |
| Describe the composition of the plasma membrane. | Phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates. |
| Why is the plasma membrane a selectively permeable barrier? | It allows only certain molecules to pass through based on size and polarity. |
| What types of materials can easily pass through the membrane? | Small, nonpolar molecules like oxygen and carbon dioxide. |
| Identify two examples of materials that easily pass through the membrane. | Oxygen and carbon dioxide. |
| Why does this type of material easily pass through the membrane? | They are small and nonpolar, allowing them to diffuse through the lipid bilayer. |
| How do large amounts of water pass through the membrane? | Through channel proteins called aquaporins. |
| What is an embedded transport protein? | A protein that spans the membrane to move specific substances across. |
| Describe the two types of transport proteins. | Channel proteins and carrier proteins. |
| What types of materials require an embedded channel or transport protein to pass through the membrane? | Ions and large polar molecules. |
| Identify two examples of materials requiring a transport protein. | Glucose and sodium ions. |
| Why does this type of material require a protein to pass through the membrane? | They are charged or too large to pass through the lipid bilayer. |
| True or False? Any molecule can use any transport protein. | False; transport proteins are specific to certain molecules. |
| How does the polarity of molecules affect its path across the plasma membrane? | Nonpolar molecules diffuse through; polar molecules require transport proteins. |
| What types of materials require a vesicle for export or a food vacuole for import? | Large macromolecules like proteins and polysaccharides. |
| Identify two examples of materials requiring bulk transport. | Proteins and bacteria. |
| Why does this type of material require bulk transport? | They are too large to fit through transport proteins. |
| Describe how the plasma membrane inhibits the movement of ions and polar molecules. | The hydrophobic core of the bilayer repels charged and polar substances. |
| Describe how ions and polar molecules are able to enter or exit the cell. | Via specific transport proteins or vesicles. |
| TRUE or FALSE: Water is able to pass through the membrane in small amounts. | True. |
| How do some small, polar uncharged molecules pass through the membrane in small amounts? | By slipping between phospholipids during temporary gaps. |
| What types of cells have a cell wall? | Plants, fungi, bacteria, and some protists. |
| How does the cell wall maintain cell structure? | Provides rigid support and protection against osmotic pressure. |
| How does the cell wall protect the cell from hypotonic solutions? | Prevents the cell from bursting by resisting internal pressure. |
| How do materials pass through the cell wall? | Through pores called plasmodesmata in plants. |
| How does the cell wall of a plant, fungi, and prokaryote differ? | Plants have cellulose; fungi have chitin; prokaryotes have peptidoglycan. |
| What is a concentration gradient? | A difference in the concentration of a substance across a space. |
| How is a concentration gradient maintained? | By active transport or continuous production/consumption of substances. |
| How are concentration gradients formed across the membrane? | By unequal distribution of ions or molecules on either side. |
| What is passive transport? | Movement of molecules down their gradient without energy input. |
| Identify two examples of passive transport. | Diffusion and osmosis. |
| Describe the direction of movement during passive transport. | From high concentration to low concentration. |
| What is active transport? | Movement of molecules against their gradient requiring energy. |
| Identify two examples of active transport. | Sodium-potassium pump and proton pump. |
| Describe the direction of movement during active transport. | From low concentration to high concentration. |
| Describe the process of endocytosis. | The cell engulfs external materials by folding the membrane inward. |
| Describe three types of endocytosis. | Phagocytosis, pinocytosis, and receptor-mediated endocytosis. |
| TRUE or FALSE: The processes of endocytosis and exocytosis are forms of active transport. | True. |
| Identify an example of a material that would require endocytosis. | Large particles or bacteria. |
| How are the food materials brought in by endocytosis digested? | Fused with lysosomes containing digestive enzymes. |
| What is exocytosis? | Vesicles fuse with the membrane to release contents outside the cell. |
| Identify an example of a material that would require exocytosis. | Hormones or neurotransmitters. |
| What is facilitated diffusion? | Passive transport of molecules across the membrane via protein channels. |
| TRUE or FALSE: Facilitated diffusion requires a transport or channel protein. | True. |
| How do charged molecules or ions pass through the membrane? | Through specific channel or carrier proteins. |
| Describe how the membrane potential changes as ions move across the membrane. | Movement of charged ions creates a voltage difference across the membrane. |
| How are large polar molecules able to move across the plasma membrane? | Via facilitated diffusion using carrier proteins. |
| What type of transport is involved with the movement of large polar molecules across the plasma membrane? | Facilitated diffusion. |
| What are aquaporins? | Channel proteins specifically for the transport of water. |
| How are large quantities of water moved across the membrane? | Through aquaporins to facilitate osmosis. |
| What does it mean if a solution is hypotonic? | The solution has a lower solute concentration than the cell. |
| What does it mean if a solution is hypertonic? | The solution has a higher solute concentration than the cell. |
| What does it mean if a solution is isotonic? | The solution has an equal solute concentration to the cell. |
| Using the chart, determine which direction the water will flow and the result to the cell. | Water moves from hypotonic to hypertonic; cell swells or shrinks accordingly. |
| What is water potential? | The potential energy of water per unit volume; determines water movement. |
| How does it explain the direction of water movement? | Water moves from high water potential to low water potential. |
| Calculate the water potential of the following solutions. | Cell A: -0.2 MPa; Cell B: 0.4 MPa. |
| Which direction will water flow based on the information in question 7? Justify. | From Cell B to Cell A because Cell B has higher water potential. |
| What is homeostasis? | Maintenance of stable internal conditions despite external changes. |
| How does movement of molecules across membranes maintain homeostasis and growth? | Regulates internal concentrations and allows nutrient uptake. |
| What is osmoregulation? | Regulation of water balance and solute concentration in a cell. |
| Identify two ways that the cell complete osmoregulation. | Contractile vacuoles and ion pumps. |
| Identify two ways that organisms complete osmoregulation. | Kidney function and behavioral adaptations. |
| Which direction would water flow if one solution A is 0.5 M and solution B is 0.2 M? | From solution B to solution A. |
| Which direction would water flow if one solution A is 0.3 M and solution B is 0.6 M? | From solution A to solution B. |
| Calculate the solute potential of the following sucrose solutions at 25 degrees Celsius. | Intracellular: -1.23 MPa; Extracellular: -0.49 MPa. |
| Assuming a pressure potential of 0.0 MPa, which direction will water flow based on the information provided in question 15? | From extracellular to intracellular. |
| Calculate the solute potential of the following NaCl solutions at 27 degrees Celsius. | Intracellular: -1.52 MPa; Extracellular: -3.04 MPa. |
| Assuming a pressure potential of 0.0 MPa, which direction will water flow based on the information provided in question 17? | From intracellular to extracellular. |
| How do organisms use osmoregulation to maintain water balance? | By pumping ions and controlling water permeability. |
| How do organisms use osmoregulation to control the internal solute composition? | By actively transporting solutes to adjust concentration. |
| What is an electrochemical gradient? | A gradient combining electrical potential and chemical concentration differences. |
| What are the two components of an electrochemical gradient? | Concentration gradient and membrane potential. |
| Describe how to establish and maintain an electrochemical gradient. | Using active transport pumps like the sodium-potassium pump. |
| Describe the process of active transport. | Proteins use ATP to move molecules against their gradient. |
| What are the necessary components for active transport? | Transport proteins and cellular energy (ATP). |
| Identify two transport proteins that maintain membrane potential. | Sodium-potassium pump and proton pump. |
| How does a Na+/K+ pump maintain the membrane potential? | Pumps 3 Na+ out and 2 K+ in, creating a charge imbalance. |
| What is the function of Na+/K+? | Maintains resting membrane potential and drives secondary transport. |
| How does an ATPase contribute to the maintenance of the membrane potential? | Hydrolyzes ATP to provide energy for pumping ions. |
| What is the function of ATPase? | Provides energy for active transport by breaking down ATP. |
| Describe how membranes allow for compartmentalization. | Separate distinct chemical environments within the cell. |
| How does the membrane of organelles allow for specific processes to take place? | Creates optimal conditions for specific enzymatic reactions. |
| Identify two examples of processes that could not take place without the use of a membrane. | Photosynthesis in chloroplasts and cellular respiration in mitochondria. |
| How do membrane bound organelles allow for compartmentalization of the cell and its functions? | Enable incompatible processes to occur simultaneously. |
| Describe how internal membrane facilitate cellular processes. | Increase surface area for enzymes and transport molecules. |
| What is the function of the inner membrane folding in the mitochondria? | Increases surface area for ATP production. |
| What is the function of the endoplasmic reticulum’s folded membrane? | Provides surface area for lipid synthesis and protein processing. |
| What is the function of thylakoid membranes in the chloroplast? | Increases surface area for light-dependent reactions. |
| What is the function of the multiple membranes and sacs found in the Golgi? | Modifies, sorts, and packages proteins for secretion. |
| Describe the effect of an increased surface area where reactions occur. | Increases the rate of metabolic reactions. |
| What is endosymbiosis? | A relationship where one organism lives inside another. |
| Describe endosymbiosis. | Theory that mitochondria and chloroplasts originated from free-living prokaryotes. |
| Identify two membrane bounded organelles that resulted from endosymbiosis. | Mitochondria and chloroplasts. |
| What is the endosymbiotic theory? | Explains the origin of eukaryotic organelles from prokaryotic ancestors. |
| How did the mitochondria and chloroplast evolve from once free-living prokaryotic cells? | Were engulfed by a host cell and formed a symbiotic relationship. |
| How did membrane bound organelles originate in eukaryotic cells? | Through infolding of the plasma membrane and endosymbiosis. |
| What are prokaryotes? | Single-celled organisms lacking a nucleus and membrane-bound organelles. |
| Identify three similarities between a prokaryotic and eukaryotic cell. | Ribosomes, cytoplasm, and plasma membrane. |
| Identify three differences between a prokaryotic and eukaryotic cell. | Nucleus, organelles, and size. |
| How is a prokaryotic cell compartmentalized? | By regions within the cytoplasm, not by membranes. |
| Describe prokaryotic internal regions with specialized structures and functions. | Nucleoid region for DNA; plasmids for resistance. |
| Describe how eukaryotic cells maintain internal membranes. | Through vesicular transport and synthesis in the ER. |
| What is the function of the inner membrane folding in the mitochondria? | Increases surface area for ATP production. |
| What is the function of the endoplasmic reticulum’s folded membrane? | Provides surface area for lipid synthesis and protein processing. |
| What is the function of thylakoid membranes in the chloroplast? | Increases surface area for light-dependent reactions. |
| What is the function of the multiple membranes and sacs found in the Golgi? | Modifies, sorts, and packages proteins for secretion. |
| Describe the function of eukaryotic internal membranes. | Separate different metabolic processes and increase efficiency. |
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