{ "chapter": "Cell Structure & Function", "count": 100, "answerIndex": "zero-based", "notice": "Original practice items including related concept variants; not official examination questions.", "questions": [ { "id": "sodium-pump", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "A toxin blocks all sodium–potassium pumps in an animal cell. Which change should develop gradually?", "options": [ "Loss of sodium and potassium gradients", "Immediate destruction of nuclear DNA", "Permanent closure of every ion channel", "Conversion of lysosomes into ribosomes" ], "answer": 0, "explanation": "The pump continually maintains unequal sodium and potassium distributions. Existing gradients persist briefly but dissipate as ions continue moving through channels." }, { "id": "lysosome-ph", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Why does rupture of a few lysosomes not normally digest the entire cytoplasm immediately?", "options": [ "Their enzymes contain no peptide bonds", "Many lysosomal enzymes work best at acidic pH", "Cytoplasm has no water", "The enzymes can digest only lipids" ], "answer": 1, "explanation": "Lysosomal hydrolases are optimized for an acidic compartment. The near-neutral cytosol reduces their activity, although extensive rupture can still injure the cell." }, { "id": "cristae", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "An increase in mitochondrial cristae most directly provides more surface for:", "options": [ "DNA replication in the nucleus", "Glycolysis in the cytosol", "Electron transport and ATP synthase", "Protein digestion in lysosomes" ], "answer": 2, "explanation": "The inner mitochondrial membrane contains electron-transport proteins and ATP synthase. Cristae increase its usable surface area." }, { "id": "osmosis-cell", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A red blood cell is placed in a solution with a lower water potential than its cytoplasm. What follows first?", "options": [ "Water enters and the cell lyses", "ATP production stops instantly", "Solute leaves by osmosis", "Water leaves and the cell shrinks" ], "answer": 3, "explanation": "Water moves from higher to lower water potential across the membrane, so it leaves the cell and the cell becomes crenated." }, { "id": "cells-nucleus-control-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "The nucleus retains intact DNA and functional transcription machinery. Which outcome follows most directly?", "options": [ "The cell can produce RNA instructions for protein synthesis", "A polypeptide can be assembled in the encoded amino-acid sequence", "Its rough endoplasmic reticulum becomes especially prominent", "They are modified, sorted and packaged into vesicles" ], "answer": 0, "explanation": "The cell can produce RNA instructions for protein synthesis. Genes serve as templates for transcription before ribosomes translate the messages." }, { "id": "cells-nucleus-control-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: the cell can produce RNA instructions for protein synthesis?", "options": [ "A ribosome binds an mRNA molecule", "The nucleus retains intact DNA and functional transcription machinery", "A cell begins secreting large quantities of protein", "New secretory proteins arrive at the Golgi apparatus" ], "answer": 1, "explanation": "The cell can produce RNA instructions for protein synthesis. Genes serve as templates for transcription before ribosomes translate the messages." }, { "id": "cells-nucleus-control-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After the nucleus retains intact DNA and functional transcription machinery, which explanation best links the change to its outcome?", "options": [ "The ribosome coordinates codon recognition and peptide-bond formation", "Attached ribosomes synthesize proteins that enter the endomembrane pathway", "Genes serve as templates for transcription before ribosomes translate the messages", "Ordered Golgi cisternae process cargo and direct it toward specific destinations" ], "answer": 2, "explanation": "The cell can produce RNA instructions for protein synthesis. Genes serve as templates for transcription before ribosomes translate the messages." }, { "id": "cells-ribosome-role-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After a ribosome binds an mRNA molecule, which observation is most likely?", "options": [ "Its rough endoplasmic reticulum becomes especially prominent", "It commonly contains numerous mitochondria", "They are modified, sorted and packaged into vesicles", "A polypeptide can be assembled in the encoded amino-acid sequence" ], "answer": 3, "explanation": "A polypeptide can be assembled in the encoded amino-acid sequence. The ribosome coordinates codon recognition and peptide-bond formation." }, { "id": "cells-ribosome-role-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "A learner records that a polypeptide can be assembled in the encoded amino-acid sequence. Which preceding event best accounts for it?", "options": [ "A ribosome binds an mRNA molecule", "New secretory proteins arrive at the Golgi apparatus", "A cell begins secreting large quantities of protein", "A cell has a persistently high demand for aerobic ATP" ], "answer": 0, "explanation": "A polypeptide can be assembled in the encoded amino-acid sequence. The ribosome coordinates codon recognition and peptide-bond formation." }, { "id": "cells-ribosome-role-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After a ribosome binds an mRNA molecule, which explanation best links the change to its outcome?", "options": [ "Attached ribosomes synthesize proteins that enter the endomembrane pathway", "The ribosome coordinates codon recognition and peptide-bond formation", "Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Ordered Golgi cisternae process cargo and direct it toward specific destinations" ], "answer": 1, "explanation": "A polypeptide can be assembled in the encoded amino-acid sequence. The ribosome coordinates codon recognition and peptide-bond formation." }, { "id": "cells-ribosome-role-integrated", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a ribosome binds an mRNA molecule?", "options": [ "They are modified, sorted and packaged into vesicles — Ordered Golgi cisternae process cargo and direct it toward specific destinations", "Its rough endoplasmic reticulum becomes especially prominent — Attached ribosomes synthesize proteins that enter the endomembrane pathway", "A polypeptide can be assembled in the encoded amino-acid sequence — The ribosome coordinates codon recognition and peptide-bond formation", "It commonly contains numerous mitochondria — Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery" ], "answer": 2, "explanation": "A polypeptide can be assembled in the encoded amino-acid sequence. The ribosome coordinates codon recognition and peptide-bond formation." }, { "id": "cells-rough-er-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "A student models this change: A cell begins secreting large quantities of protein. What should the model predict first?", "options": [ "They are modified, sorted and packaged into vesicles", "It commonly contains numerous mitochondria", "Electrons become energized for the light-dependent reactions", "Its rough endoplasmic reticulum becomes especially prominent" ], "answer": 3, "explanation": "Its rough endoplasmic reticulum becomes especially prominent. Attached ribosomes synthesize proteins that enter the endomembrane pathway." }, { "id": "cells-rough-er-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "What is the most likely cause when its rough endoplasmic reticulum becomes especially prominent?", "options": [ "A cell begins secreting large quantities of protein", "A cell has a persistently high demand for aerobic ATP", "Chlorophyll absorbs suitable wavelengths of light", "New secretory proteins arrive at the Golgi apparatus" ], "answer": 0, "explanation": "Its rough endoplasmic reticulum becomes especially prominent. Attached ribosomes synthesize proteins that enter the endomembrane pathway." }, { "id": "cells-rough-er-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After a cell begins secreting large quantities of protein, which explanation best links the change to its outcome?", "options": [ "Ordered Golgi cisternae process cargo and direct it toward specific destinations", "Attached ribosomes synthesize proteins that enter the endomembrane pathway", "Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Excited chlorophyll electrons enter transport chains in thylakoid membranes" ], "answer": 1, "explanation": "Its rough endoplasmic reticulum becomes especially prominent. Attached ribosomes synthesize proteins that enter the endomembrane pathway." }, { "id": "cells-rough-er-integrated", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a cell begins secreting large quantities of protein?", "options": [ "They are modified, sorted and packaged into vesicles — Ordered Golgi cisternae process cargo and direct it toward specific destinations", "It commonly contains numerous mitochondria — Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Its rough endoplasmic reticulum becomes especially prominent — Attached ribosomes synthesize proteins that enter the endomembrane pathway", "Electrons become energized for the light-dependent reactions — Excited chlorophyll electrons enter transport chains in thylakoid membranes" ], "answer": 2, "explanation": "Its rough endoplasmic reticulum becomes especially prominent. Attached ribosomes synthesize proteins that enter the endomembrane pathway." }, { "id": "cells-golgi-packaging-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which immediate result is most consistent with this condition: New secretory proteins arrive at the Golgi apparatus?", "options": [ "It commonly contains numerous mitochondria", "Electrons become energized for the light-dependent reactions", "Its undegraded substrate accumulates inside lysosomes", "They are modified, sorted and packaged into vesicles" ], "answer": 3, "explanation": "They are modified, sorted and packaged into vesicles. Ordered Golgi cisternae process cargo and direct it toward specific destinations." }, { "id": "cells-golgi-packaging-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which condition would most specifically produce this result: they are modified, sorted and packaged into vesicles?", "options": [ "New secretory proteins arrive at the Golgi apparatus", "A cell has a persistently high demand for aerobic ATP", "Chlorophyll absorbs suitable wavelengths of light", "A lysosomal hydrolase is absent because of a genetic defect" ], "answer": 0, "explanation": "They are modified, sorted and packaged into vesicles. Ordered Golgi cisternae process cargo and direct it toward specific destinations." }, { "id": "cells-golgi-packaging-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After new secretory proteins arrive at the Golgi apparatus, which explanation best links the change to its outcome?", "options": [ "Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Ordered Golgi cisternae process cargo and direct it toward specific destinations", "Excited chlorophyll electrons enter transport chains in thylakoid membranes", "Macromolecular recycling stalls when the required acidic enzyme is missing" ], "answer": 1, "explanation": "They are modified, sorted and packaged into vesicles. Ordered Golgi cisternae process cargo and direct it toward specific destinations." }, { "id": "cells-golgi-packaging-integrated", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: new secretory proteins arrive at the Golgi apparatus?", "options": [ "It commonly contains numerous mitochondria — Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Electrons become energized for the light-dependent reactions — Excited chlorophyll electrons enter transport chains in thylakoid membranes", "They are modified, sorted and packaged into vesicles — Ordered Golgi cisternae process cargo and direct it toward specific destinations", "Its undegraded substrate accumulates inside lysosomes — Macromolecular recycling stalls when the required acidic enzyme is missing" ], "answer": 2, "explanation": "They are modified, sorted and packaged into vesicles. Ordered Golgi cisternae process cargo and direct it toward specific destinations." }, { "id": "cells-mitochondria-demand-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "A cell has a persistently high demand for aerobic ATP. Which outcome follows most directly?", "options": [ "Its capacity for membrane transport and absorption increases", "Electrons become energized for the light-dependent reactions", "Its undegraded substrate accumulates inside lysosomes", "It commonly contains numerous mitochondria" ], "answer": 3, "explanation": "It commonly contains numerous mitochondria. Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery." }, { "id": "cells-mitochondria-demand-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: it commonly contains numerous mitochondria?", "options": [ "A cell has a persistently high demand for aerobic ATP", "Chlorophyll absorbs suitable wavelengths of light", "A lysosomal hydrolase is absent because of a genetic defect", "An epithelial cell develops many microvilli" ], "answer": 0, "explanation": "It commonly contains numerous mitochondria. Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery." }, { "id": "cells-mitochondria-demand-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After a cell has a persistently high demand for aerobic ATP, which explanation best links the change to its outcome?", "options": [ "Excited chlorophyll electrons enter transport chains in thylakoid membranes", "Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Macromolecular recycling stalls when the required acidic enzyme is missing", "Membrane folds create a larger surface area for carriers and channels" ], "answer": 1, "explanation": "It commonly contains numerous mitochondria. Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery." }, { "id": "cells-mitochondria-demand-integrated", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a cell has a persistently high demand for aerobic ATP?", "options": [ "Electrons become energized for the light-dependent reactions — Excited chlorophyll electrons enter transport chains in thylakoid membranes", "Its undegraded substrate accumulates inside lysosomes — Macromolecular recycling stalls when the required acidic enzyme is missing", "It commonly contains numerous mitochondria — Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery", "Its capacity for membrane transport and absorption increases — Membrane folds create a larger surface area for carriers and channels" ], "answer": 2, "explanation": "It commonly contains numerous mitochondria. Mitochondria house the citric-acid cycle and oxidative-phosphorylation machinery." }, { "id": "cells-chloroplast-light-outcome", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After chlorophyll absorbs suitable wavelengths of light, which observation is most likely?", "options": [ "Its undegraded substrate accumulates inside lysosomes", "Net diffusion initially occurs at a faster rate", "Its capacity for membrane transport and absorption increases", "Electrons become energized for the light-dependent reactions" ], "answer": 3, "explanation": "Electrons become energized for the light-dependent reactions. Excited chlorophyll electrons enter transport chains in thylakoid membranes." }, { "id": "cells-chloroplast-light-cause", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "A learner records that electrons become energized for the light-dependent reactions. Which preceding event best accounts for it?", "options": [ "Chlorophyll absorbs suitable wavelengths of light", "An epithelial cell develops many microvilli", "A lysosomal hydrolase is absent because of a genetic defect", "The concentration difference across a permeable membrane becomes steeper" ], "answer": 0, "explanation": "Electrons become energized for the light-dependent reactions. Excited chlorophyll electrons enter transport chains in thylakoid membranes." }, { "id": "cells-chloroplast-light-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "After chlorophyll absorbs suitable wavelengths of light, which explanation best links the change to its outcome?", "options": [ "Macromolecular recycling stalls when the required acidic enzyme is missing", "Excited chlorophyll electrons enter transport chains in thylakoid membranes", "A larger imbalance produces more random movement in the downhill than uphill direction", "Membrane folds create a larger surface area for carriers and channels" ], "answer": 1, "explanation": "Electrons become energized for the light-dependent reactions. Excited chlorophyll electrons enter transport chains in thylakoid membranes." }, { "id": "cells-chloroplast-light-integrated", "chapter": "Cell Structure & Function", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: chlorophyll absorbs suitable wavelengths of light?", "options": [ "Its capacity for membrane transport and absorption increases — Membrane folds create a larger surface area for carriers and channels", "Its undegraded substrate accumulates inside lysosomes — Macromolecular recycling stalls when the required acidic enzyme is missing", "Electrons become energized for the light-dependent reactions — Excited chlorophyll electrons enter transport chains in thylakoid membranes", "Net diffusion initially occurs at a faster rate — A larger imbalance produces more random movement in the downhill than uphill direction" ], "answer": 2, "explanation": "Electrons become energized for the light-dependent reactions. Excited chlorophyll electrons enter transport chains in thylakoid membranes." }, { "id": "cells-lysosome-defect-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A student models this change: A lysosomal hydrolase is absent because of a genetic defect. What should the model predict first?", "options": [ "Its capacity for membrane transport and absorption increases", "Net diffusion initially occurs at a faster rate", "The solute crosses without direct ATP expenditure", "Its undegraded substrate accumulates inside lysosomes" ], "answer": 3, "explanation": "Its undegraded substrate accumulates inside lysosomes. Macromolecular recycling stalls when the required acidic enzyme is missing." }, { "id": "cells-lysosome-defect-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "What is the most likely cause when its undegraded substrate accumulates inside lysosomes?", "options": [ "A lysosomal hydrolase is absent because of a genetic defect", "The concentration difference across a permeable membrane becomes steeper", "A polar solute moves down its concentration gradient through a carrier", "An epithelial cell develops many microvilli" ], "answer": 0, "explanation": "Its undegraded substrate accumulates inside lysosomes. Macromolecular recycling stalls when the required acidic enzyme is missing." }, { "id": "cells-lysosome-defect-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a lysosomal hydrolase is absent because of a genetic defect, which explanation best links the change to its outcome?", "options": [ "Membrane folds create a larger surface area for carriers and channels", "Macromolecular recycling stalls when the required acidic enzyme is missing", "A larger imbalance produces more random movement in the downhill than uphill direction", "A membrane protein provides a selective hydrophilic pathway for passive transport" ], "answer": 1, "explanation": "Its undegraded substrate accumulates inside lysosomes. Macromolecular recycling stalls when the required acidic enzyme is missing." }, { "id": "cells-microvilli-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: An epithelial cell develops many microvilli?", "options": [ "Net diffusion initially occurs at a faster rate", "The solute crosses without direct ATP expenditure", "Its capacity for membrane transport and absorption increases", "The solute can move against its electrochemical gradient" ], "answer": 2, "explanation": "Its capacity for membrane transport and absorption increases. Membrane folds create a larger surface area for carriers and channels." }, { "id": "cells-microvilli-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: its capacity for membrane transport and absorption increases?", "options": [ "A membrane pump hydrolyses ATP while binding a solute", "The concentration difference across a permeable membrane becomes steeper", "A polar solute moves down its concentration gradient through a carrier", "An epithelial cell develops many microvilli" ], "answer": 3, "explanation": "Its capacity for membrane transport and absorption increases. Membrane folds create a larger surface area for carriers and channels." }, { "id": "cells-microvilli-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After an epithelial cell develops many microvilli, which explanation best links the change to its outcome?", "options": [ "Membrane folds create a larger surface area for carriers and channels", "A larger imbalance produces more random movement in the downhill than uphill direction", "A membrane protein provides a selective hydrophilic pathway for passive transport", "Phosphorylation drives conformational changes that alternately expose the binding site" ], "answer": 0, "explanation": "Its capacity for membrane transport and absorption increases. Membrane folds create a larger surface area for carriers and channels." }, { "id": "cells-microvilli-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: an epithelial cell develops many microvilli?", "options": [ "Net diffusion initially occurs at a faster rate — A larger imbalance produces more random movement in the downhill than uphill direction", "Its capacity for membrane transport and absorption increases — Membrane folds create a larger surface area for carriers and channels", "The solute crosses without direct ATP expenditure — A membrane protein provides a selective hydrophilic pathway for passive transport", "The solute can move against its electrochemical gradient — Phosphorylation drives conformational changes that alternately expose the binding site" ], "answer": 1, "explanation": "Its capacity for membrane transport and absorption increases. Membrane folds create a larger surface area for carriers and channels." }, { "id": "cells-diffusion-gradient-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "The concentration difference across a permeable membrane becomes steeper. Which outcome follows most directly?", "options": [ "The solute can move against its electrochemical gradient", "The solute crosses without direct ATP expenditure", "Net diffusion initially occurs at a faster rate", "Water enters and the cell may lyse" ], "answer": 2, "explanation": "Net diffusion initially occurs at a faster rate. A larger imbalance produces more random movement in the downhill than uphill direction." }, { "id": "cells-diffusion-gradient-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which change most directly explains this observation: net diffusion initially occurs at a faster rate?", "options": [ "A polar solute moves down its concentration gradient through a carrier", "An animal cell is placed in a strongly hypotonic solution", "A membrane pump hydrolyses ATP while binding a solute", "The concentration difference across a permeable membrane becomes steeper" ], "answer": 3, "explanation": "Net diffusion initially occurs at a faster rate. A larger imbalance produces more random movement in the downhill than uphill direction." }, { "id": "cells-diffusion-gradient-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After the concentration difference across a permeable membrane becomes steeper, which explanation best links the change to its outcome?", "options": [ "A larger imbalance produces more random movement in the downhill than uphill direction", "Phosphorylation drives conformational changes that alternately expose the binding site", "A membrane protein provides a selective hydrophilic pathway for passive transport", "Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling" ], "answer": 0, "explanation": "Net diffusion initially occurs at a faster rate. A larger imbalance produces more random movement in the downhill than uphill direction." }, { "id": "cells-diffusion-gradient-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: the concentration difference across a permeable membrane becomes steeper?", "options": [ "The solute crosses without direct ATP expenditure — A membrane protein provides a selective hydrophilic pathway for passive transport", "Net diffusion initially occurs at a faster rate — A larger imbalance produces more random movement in the downhill than uphill direction", "Water enters and the cell may lyse — Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "The solute can move against its electrochemical gradient — Phosphorylation drives conformational changes that alternately expose the binding site" ], "answer": 1, "explanation": "Net diffusion initially occurs at a faster rate. A larger imbalance produces more random movement in the downhill than uphill direction." }, { "id": "cells-facilitated-diffusion-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a polar solute moves down its concentration gradient through a carrier, which observation is most likely?", "options": [ "The solute can move against its electrochemical gradient", "Water enters and the cell may lyse", "The solute crosses without direct ATP expenditure", "It becomes turgid rather than bursting" ], "answer": 2, "explanation": "The solute crosses without direct ATP expenditure. A membrane protein provides a selective hydrophilic pathway for passive transport." }, { "id": "cells-facilitated-diffusion-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A learner records that the solute crosses without direct ATP expenditure. Which preceding event best accounts for it?", "options": [ "A membrane pump hydrolyses ATP while binding a solute", "An animal cell is placed in a strongly hypotonic solution", "A healthy plant cell is placed in a hypotonic solution", "A polar solute moves down its concentration gradient through a carrier" ], "answer": 3, "explanation": "The solute crosses without direct ATP expenditure. A membrane protein provides a selective hydrophilic pathway for passive transport." }, { "id": "cells-facilitated-diffusion-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a polar solute moves down its concentration gradient through a carrier, which explanation best links the change to its outcome?", "options": [ "A membrane protein provides a selective hydrophilic pathway for passive transport", "Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "Water entry raises turgor pressure until the rigid wall opposes further expansion", "Phosphorylation drives conformational changes that alternately expose the binding site" ], "answer": 0, "explanation": "The solute crosses without direct ATP expenditure. A membrane protein provides a selective hydrophilic pathway for passive transport." }, { "id": "cells-facilitated-diffusion-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a polar solute moves down its concentration gradient through a carrier?", "options": [ "The solute can move against its electrochemical gradient — Phosphorylation drives conformational changes that alternately expose the binding site", "The solute crosses without direct ATP expenditure — A membrane protein provides a selective hydrophilic pathway for passive transport", "Water enters and the cell may lyse — Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "It becomes turgid rather than bursting — Water entry raises turgor pressure until the rigid wall opposes further expansion" ], "answer": 1, "explanation": "The solute crosses without direct ATP expenditure. A membrane protein provides a selective hydrophilic pathway for passive transport." }, { "id": "cells-active-transport-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A student models this change: A membrane pump hydrolyses ATP while binding a solute. What should the model predict first?", "options": [ "Water enters and the cell may lyse", "It becomes turgid rather than bursting", "The solute can move against its electrochemical gradient", "The particle enters the cell inside a vesicle" ], "answer": 2, "explanation": "The solute can move against its electrochemical gradient. Phosphorylation drives conformational changes that alternately expose the binding site." }, { "id": "cells-active-transport-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "What is the most likely cause when the solute can move against its electrochemical gradient?", "options": [ "An animal cell is placed in a strongly hypotonic solution", "A healthy plant cell is placed in a hypotonic solution", "The plasma membrane surrounds a large extracellular particle", "A membrane pump hydrolyses ATP while binding a solute" ], "answer": 3, "explanation": "The solute can move against its electrochemical gradient. Phosphorylation drives conformational changes that alternately expose the binding site." }, { "id": "cells-active-transport-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a membrane pump hydrolyses ATP while binding a solute, which explanation best links the change to its outcome?", "options": [ "Phosphorylation drives conformational changes that alternately expose the binding site", "Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "Water entry raises turgor pressure until the rigid wall opposes further expansion", "Membrane invagination and scission perform bulk transport by endocytosis" ], "answer": 0, "explanation": "The solute can move against its electrochemical gradient. Phosphorylation drives conformational changes that alternately expose the binding site." }, { "id": "cells-active-transport-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a membrane pump hydrolyses ATP while binding a solute?", "options": [ "Water enters and the cell may lyse — Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "The solute can move against its electrochemical gradient — Phosphorylation drives conformational changes that alternately expose the binding site", "It becomes turgid rather than bursting — Water entry raises turgor pressure until the rigid wall opposes further expansion", "The particle enters the cell inside a vesicle — Membrane invagination and scission perform bulk transport by endocytosis" ], "answer": 1, "explanation": "The solute can move against its electrochemical gradient. Phosphorylation drives conformational changes that alternately expose the binding site." }, { "id": "cells-animal-hypotonic-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: An animal cell is placed in a strongly hypotonic solution?", "options": [ "It becomes turgid rather than bursting", "The particle enters the cell inside a vesicle", "Water enters and the cell may lyse", "Its soluble contents are released outside the cell" ], "answer": 2, "explanation": "Water enters and the cell may lyse. Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling." }, { "id": "cells-animal-hypotonic-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: water enters and the cell may lyse?", "options": [ "A secretory vesicle fuses with the plasma membrane", "A healthy plant cell is placed in a hypotonic solution", "The plasma membrane surrounds a large extracellular particle", "An animal cell is placed in a strongly hypotonic solution" ], "answer": 3, "explanation": "Water enters and the cell may lyse. Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling." }, { "id": "cells-animal-hypotonic-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After an animal cell is placed in a strongly hypotonic solution, which explanation best links the change to its outcome?", "options": [ "Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "Water entry raises turgor pressure until the rigid wall opposes further expansion", "Membrane invagination and scission perform bulk transport by endocytosis", "Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids" ], "answer": 0, "explanation": "Water enters and the cell may lyse. Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling." }, { "id": "cells-animal-hypotonic-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: an animal cell is placed in a strongly hypotonic solution?", "options": [ "It becomes turgid rather than bursting — Water entry raises turgor pressure until the rigid wall opposes further expansion", "Water enters and the cell may lyse — Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling", "The particle enters the cell inside a vesicle — Membrane invagination and scission perform bulk transport by endocytosis", "Its soluble contents are released outside the cell — Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids" ], "answer": 1, "explanation": "Water enters and the cell may lyse. Osmosis drives water toward the more concentrated cytoplasm without a rigid wall to resist swelling." }, { "id": "cells-plant-hypotonic-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A healthy plant cell is placed in a hypotonic solution. Which outcome follows most directly?", "options": [ "Its soluble contents are released outside the cell", "The particle enters the cell inside a vesicle", "It becomes turgid rather than bursting", "A bipolar spindle forms" ], "answer": 2, "explanation": "It becomes turgid rather than bursting. Water entry raises turgor pressure until the rigid wall opposes further expansion." }, { "id": "cells-plant-hypotonic-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which change most directly explains this observation: it becomes turgid rather than bursting?", "options": [ "The plasma membrane surrounds a large extracellular particle", "Centrosomes organize microtubules as an animal cell enters mitosis", "A secretory vesicle fuses with the plasma membrane", "A healthy plant cell is placed in a hypotonic solution" ], "answer": 3, "explanation": "It becomes turgid rather than bursting. Water entry raises turgor pressure until the rigid wall opposes further expansion." }, { "id": "cells-plant-hypotonic-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a healthy plant cell is placed in a hypotonic solution, which explanation best links the change to its outcome?", "options": [ "Water entry raises turgor pressure until the rigid wall opposes further expansion", "Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids", "Membrane invagination and scission perform bulk transport by endocytosis", "Microtubules extend from opposite poles and attach to chromosome kinetochores" ], "answer": 0, "explanation": "It becomes turgid rather than bursting. Water entry raises turgor pressure until the rigid wall opposes further expansion." }, { "id": "cells-endocytosis-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After the plasma membrane surrounds a large extracellular particle, which observation is most likely?", "options": [ "Its soluble contents are released outside the cell", "The particle enters the cell inside a vesicle", "A bipolar spindle forms", "It can still translate proteins in its cytoplasm" ], "answer": 1, "explanation": "The particle enters the cell inside a vesicle. Membrane invagination and scission perform bulk transport by endocytosis." }, { "id": "cells-endocytosis-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A learner records that the particle enters the cell inside a vesicle. Which preceding event best accounts for it?", "options": [ "A secretory vesicle fuses with the plasma membrane", "Centrosomes organize microtubules as an animal cell enters mitosis", "The plasma membrane surrounds a large extracellular particle", "A bacterial cell lacks membrane-bound organelles" ], "answer": 2, "explanation": "The particle enters the cell inside a vesicle. Membrane invagination and scission perform bulk transport by endocytosis." }, { "id": "cells-endocytosis-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After the plasma membrane surrounds a large extracellular particle, which explanation best links the change to its outcome?", "options": [ "Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids", "Microtubules extend from opposite poles and attach to chromosome kinetochores", "Free 70S ribosomes perform translation without an endoplasmic reticulum", "Membrane invagination and scission perform bulk transport by endocytosis" ], "answer": 3, "explanation": "The particle enters the cell inside a vesicle. Membrane invagination and scission perform bulk transport by endocytosis." }, { "id": "cells-endocytosis-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: the plasma membrane surrounds a large extracellular particle?", "options": [ "The particle enters the cell inside a vesicle — Membrane invagination and scission perform bulk transport by endocytosis", "Its soluble contents are released outside the cell — Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids", "A bipolar spindle forms — Microtubules extend from opposite poles and attach to chromosome kinetochores", "It can still translate proteins in its cytoplasm — Free 70S ribosomes perform translation without an endoplasmic reticulum" ], "answer": 0, "explanation": "The particle enters the cell inside a vesicle. Membrane invagination and scission perform bulk transport by endocytosis." }, { "id": "cells-exocytosis-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A student models this change: A secretory vesicle fuses with the plasma membrane. What should the model predict first?", "options": [ "A bipolar spindle forms", "Its soluble contents are released outside the cell", "It can still translate proteins in its cytoplasm", "Its surface-area-to-volume ratio decreases" ], "answer": 1, "explanation": "Its soluble contents are released outside the cell. Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids." }, { "id": "cells-exocytosis-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "What is the most likely cause when its soluble contents are released outside the cell?", "options": [ "Centrosomes organize microtubules as an animal cell enters mitosis", "A bacterial cell lacks membrane-bound organelles", "A secretory vesicle fuses with the plasma membrane", "A cell increases in diameter without changing shape" ], "answer": 2, "explanation": "Its soluble contents are released outside the cell. Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids." }, { "id": "cells-exocytosis-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a secretory vesicle fuses with the plasma membrane, which explanation best links the change to its outcome?", "options": [ "Volume rises with the cube of length while surface area rises with the square", "Microtubules extend from opposite poles and attach to chromosome kinetochores", "Free 70S ribosomes perform translation without an endoplasmic reticulum", "Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids" ], "answer": 3, "explanation": "Its soluble contents are released outside the cell. Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids." }, { "id": "cells-exocytosis-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a secretory vesicle fuses with the plasma membrane?", "options": [ "Its soluble contents are released outside the cell — Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids", "A bipolar spindle forms — Microtubules extend from opposite poles and attach to chromosome kinetochores", "It can still translate proteins in its cytoplasm — Free 70S ribosomes perform translation without an endoplasmic reticulum", "Its surface-area-to-volume ratio decreases — Volume rises with the cube of length while surface area rises with the square" ], "answer": 0, "explanation": "Its soluble contents are released outside the cell. Fusion joins the vesicle lumen to the extracellular space while adding membrane lipids." }, { "id": "cells-centriole-spindle-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Centrosomes organize microtubules as an animal cell enters mitosis?", "options": [ "It can still translate proteins in its cytoplasm", "A bipolar spindle forms", "Oxidative phosphorylation and most aerobic ATP production rapidly fall", "Its surface-area-to-volume ratio decreases" ], "answer": 1, "explanation": "A bipolar spindle forms. Microtubules extend from opposite poles and attach to chromosome kinetochores." }, { "id": "cells-centriole-spindle-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: a bipolar spindle forms?", "options": [ "A cell increases in diameter without changing shape", "A bacterial cell lacks membrane-bound organelles", "Centrosomes organize microtubules as an animal cell enters mitosis", "Cyanide blocks the final electron carrier in mitochondria" ], "answer": 2, "explanation": "A bipolar spindle forms. Microtubules extend from opposite poles and attach to chromosome kinetochores." }, { "id": "cells-centriole-spindle-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After centrosomes organize microtubules as an animal cell enters mitosis, which explanation best links the change to its outcome?", "options": [ "Free 70S ribosomes perform translation without an endoplasmic reticulum", "Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase", "Volume rises with the cube of length while surface area rises with the square", "Microtubules extend from opposite poles and attach to chromosome kinetochores" ], "answer": 3, "explanation": "A bipolar spindle forms. Microtubules extend from opposite poles and attach to chromosome kinetochores." }, { "id": "cells-centriole-spindle-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: centrosomes organize microtubules as an animal cell enters mitosis?", "options": [ "A bipolar spindle forms — Microtubules extend from opposite poles and attach to chromosome kinetochores", "Its surface-area-to-volume ratio decreases — Volume rises with the cube of length while surface area rises with the square", "It can still translate proteins in its cytoplasm — Free 70S ribosomes perform translation without an endoplasmic reticulum", "Oxidative phosphorylation and most aerobic ATP production rapidly fall — Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase" ], "answer": 0, "explanation": "A bipolar spindle forms. Microtubules extend from opposite poles and attach to chromosome kinetochores." }, { "id": "cells-prokaryote-ribosome-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A bacterial cell lacks membrane-bound organelles. Which outcome follows most directly?", "options": [ "Its surface-area-to-volume ratio decreases", "It can still translate proteins in its cytoplasm", "Oxidative phosphorylation and most aerobic ATP production rapidly fall", "Ion gradients weaken and osmotic swelling may develop" ], "answer": 1, "explanation": "It can still translate proteins in its cytoplasm. Free 70S ribosomes perform translation without an endoplasmic reticulum." }, { "id": "cells-prokaryote-ribosome-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which change most directly explains this observation: it can still translate proteins in its cytoplasm?", "options": [ "A cell increases in diameter without changing shape", "Cyanide blocks the final electron carrier in mitochondria", "A bacterial cell lacks membrane-bound organelles", "A sodium-potassium pump inhibitor is applied for several hours" ], "answer": 2, "explanation": "It can still translate proteins in its cytoplasm. Free 70S ribosomes perform translation without an endoplasmic reticulum." }, { "id": "cells-prokaryote-ribosome-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a bacterial cell lacks membrane-bound organelles, which explanation best links the change to its outcome?", "options": [ "Volume rises with the cube of length while surface area rises with the square", "Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase", "Sodium accumulates intracellularly and water follows the rising solute concentration", "Free 70S ribosomes perform translation without an endoplasmic reticulum" ], "answer": 3, "explanation": "It can still translate proteins in its cytoplasm. Free 70S ribosomes perform translation without an endoplasmic reticulum." }, { "id": "cells-prokaryote-ribosome-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a bacterial cell lacks membrane-bound organelles?", "options": [ "It can still translate proteins in its cytoplasm — Free 70S ribosomes perform translation without an endoplasmic reticulum", "Oxidative phosphorylation and most aerobic ATP production rapidly fall — Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase", "Ion gradients weaken and osmotic swelling may develop — Sodium accumulates intracellularly and water follows the rising solute concentration", "Its surface-area-to-volume ratio decreases — Volume rises with the cube of length while surface area rises with the square" ], "answer": 0, "explanation": "It can still translate proteins in its cytoplasm. Free 70S ribosomes perform translation without an endoplasmic reticulum." }, { "id": "cells-surface-volume-outcome", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a cell increases in diameter without changing shape, which observation is most likely?", "options": [ "Oxidative phosphorylation and most aerobic ATP production rapidly fall", "Its surface-area-to-volume ratio decreases", "Ion gradients weaken and osmotic swelling may develop", "It remains more fluid than a membrane rich in saturated fatty acids" ], "answer": 1, "explanation": "Its surface-area-to-volume ratio decreases. Volume rises with the cube of length while surface area rises with the square." }, { "id": "cells-surface-volume-cause", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "A learner records that its surface-area-to-volume ratio decreases. Which preceding event best accounts for it?", "options": [ "Cyanide blocks the final electron carrier in mitochondria", "A sodium-potassium pump inhibitor is applied for several hours", "A cell increases in diameter without changing shape", "A membrane contains a high proportion of unsaturated fatty acids at low temperature" ], "answer": 2, "explanation": "Its surface-area-to-volume ratio decreases. Volume rises with the cube of length while surface area rises with the square." }, { "id": "cells-surface-volume-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "After a cell increases in diameter without changing shape, which explanation best links the change to its outcome?", "options": [ "Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase", "Sodium accumulates intracellularly and water follows the rising solute concentration", "Cis double-bond kinks prevent close packing and extensive van der Waals interactions", "Volume rises with the cube of length while surface area rises with the square" ], "answer": 3, "explanation": "Its surface-area-to-volume ratio decreases. Volume rises with the cube of length while surface area rises with the square." }, { "id": "cells-surface-volume-integrated", "chapter": "Cell Structure & Function", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a cell increases in diameter without changing shape?", "options": [ "Its surface-area-to-volume ratio decreases — Volume rises with the cube of length while surface area rises with the square", "Oxidative phosphorylation and most aerobic ATP production rapidly fall — Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase", "Ion gradients weaken and osmotic swelling may develop — Sodium accumulates intracellularly and water follows the rising solute concentration", "It remains more fluid than a membrane rich in saturated fatty acids — Cis double-bond kinks prevent close packing and extensive van der Waals interactions" ], "answer": 0, "explanation": "Its surface-area-to-volume ratio decreases. Volume rises with the cube of length while surface area rises with the square." }, { "id": "cells-cyanide-mitochondria-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "A student models this change: Cyanide blocks the final electron carrier in mitochondria. What should the model predict first?", "options": [ "Ion gradients weaken and osmotic swelling may develop", "Oxidative phosphorylation and most aerobic ATP production rapidly fall", "It remains more fluid than a membrane rich in saturated fatty acids", "Long-distance vesicle transport inside the cell slows" ], "answer": 1, "explanation": "Oxidative phosphorylation and most aerobic ATP production rapidly fall. Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase." }, { "id": "cells-cyanide-mitochondria-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "What is the most likely cause when oxidative phosphorylation and most aerobic ATP production rapidly fall?", "options": [ "A sodium-potassium pump inhibitor is applied for several hours", "A membrane contains a high proportion of unsaturated fatty acids at low temperature", "Cyanide blocks the final electron carrier in mitochondria", "Motor proteins are prevented from moving along cytoskeletal tracks" ], "answer": 2, "explanation": "Oxidative phosphorylation and most aerobic ATP production rapidly fall. Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase." }, { "id": "cells-cyanide-mitochondria-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After cyanide blocks the final electron carrier in mitochondria, which explanation best links the change to its outcome?", "options": [ "Kinesin and dynein normally carry cargo directionally along microtubules", "Sodium accumulates intracellularly and water follows the rising solute concentration", "Cis double-bond kinks prevent close packing and extensive van der Waals interactions", "Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase" ], "answer": 3, "explanation": "Oxidative phosphorylation and most aerobic ATP production rapidly fall. Electron flow stops, proton pumping ceases and the gradient cannot power ATP synthase." }, { "id": "cells-ouabain-volume-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: A sodium-potassium pump inhibitor is applied for several hours?", "options": [ "Ion gradients weaken and osmotic swelling may develop", "Long-distance vesicle transport inside the cell slows", "Production of new ribosomal subunits declines", "It remains more fluid than a membrane rich in saturated fatty acids" ], "answer": 0, "explanation": "Ion gradients weaken and osmotic swelling may develop. Sodium accumulates intracellularly and water follows the rising solute concentration." }, { "id": "cells-ouabain-volume-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: ion gradients weaken and osmotic swelling may develop?", "options": [ "A membrane contains a high proportion of unsaturated fatty acids at low temperature", "A sodium-potassium pump inhibitor is applied for several hours", "Motor proteins are prevented from moving along cytoskeletal tracks", "Ribosomal RNA synthesis in the nucleolus is inhibited" ], "answer": 1, "explanation": "Ion gradients weaken and osmotic swelling may develop. Sodium accumulates intracellularly and water follows the rising solute concentration." }, { "id": "cells-ouabain-volume-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After a sodium-potassium pump inhibitor is applied for several hours, which explanation best links the change to its outcome?", "options": [ "Cis double-bond kinks prevent close packing and extensive van der Waals interactions", "Kinesin and dynein normally carry cargo directionally along microtubules", "Sodium accumulates intracellularly and water follows the rising solute concentration", "The nucleolus normally combines rRNA with imported ribosomal proteins" ], "answer": 2, "explanation": "Ion gradients weaken and osmotic swelling may develop. Sodium accumulates intracellularly and water follows the rising solute concentration." }, { "id": "cells-ouabain-volume-integrated", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: a sodium-potassium pump inhibitor is applied for several hours?", "options": [ "It remains more fluid than a membrane rich in saturated fatty acids — Cis double-bond kinks prevent close packing and extensive van der Waals interactions", "Long-distance vesicle transport inside the cell slows — Kinesin and dynein normally carry cargo directionally along microtubules", "Production of new ribosomal subunits declines — The nucleolus normally combines rRNA with imported ribosomal proteins", "Ion gradients weaken and osmotic swelling may develop — Sodium accumulates intracellularly and water follows the rising solute concentration" ], "answer": 3, "explanation": "Ion gradients weaken and osmotic swelling may develop. Sodium accumulates intracellularly and water follows the rising solute concentration." }, { "id": "cells-membrane-low-temp-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "A membrane contains a high proportion of unsaturated fatty acids at low temperature. Which outcome follows most directly?", "options": [ "It remains more fluid than a membrane rich in saturated fatty acids", "Long-distance vesicle transport inside the cell slows", "Production of new ribosomal subunits declines", "Hydrogen peroxide can accumulate and damage the cell" ], "answer": 0, "explanation": "It remains more fluid than a membrane rich in saturated fatty acids. Cis double-bond kinks prevent close packing and extensive van der Waals interactions." }, { "id": "cells-membrane-low-temp-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which change most directly explains this observation: it remains more fluid than a membrane rich in saturated fatty acids?", "options": [ "Motor proteins are prevented from moving along cytoskeletal tracks", "A membrane contains a high proportion of unsaturated fatty acids at low temperature", "Ribosomal RNA synthesis in the nucleolus is inhibited", "Catalase is absent from peroxisomes" ], "answer": 1, "explanation": "It remains more fluid than a membrane rich in saturated fatty acids. Cis double-bond kinks prevent close packing and extensive van der Waals interactions." }, { "id": "cells-membrane-low-temp-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After a membrane contains a high proportion of unsaturated fatty acids at low temperature, which explanation best links the change to its outcome?", "options": [ "Kinesin and dynein normally carry cargo directionally along microtubules", "The nucleolus normally combines rRNA with imported ribosomal proteins", "Cis double-bond kinks prevent close packing and extensive van der Waals interactions", "Catalase normally converts the reactive peroxide into water and oxygen" ], "answer": 2, "explanation": "It remains more fluid than a membrane rich in saturated fatty acids. Cis double-bond kinks prevent close packing and extensive van der Waals interactions." }, { "id": "cells-membrane-low-temp-integrated", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: a membrane contains a high proportion of unsaturated fatty acids at low temperature?", "options": [ "Long-distance vesicle transport inside the cell slows — Kinesin and dynein normally carry cargo directionally along microtubules", "Production of new ribosomal subunits declines — The nucleolus normally combines rRNA with imported ribosomal proteins", "Hydrogen peroxide can accumulate and damage the cell — Catalase normally converts the reactive peroxide into water and oxygen", "It remains more fluid than a membrane rich in saturated fatty acids — Cis double-bond kinks prevent close packing and extensive van der Waals interactions" ], "answer": 3, "explanation": "It remains more fluid than a membrane rich in saturated fatty acids. Cis double-bond kinks prevent close packing and extensive van der Waals interactions." }, { "id": "cells-vesicle-cytoskeleton-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After motor proteins are prevented from moving along cytoskeletal tracks, which observation is most likely?", "options": [ "Long-distance vesicle transport inside the cell slows", "Production of new ribosomal subunits declines", "Hydrogen peroxide can accumulate and damage the cell", "The cell can produce RNA instructions for protein synthesis" ], "answer": 0, "explanation": "Long-distance vesicle transport inside the cell slows. Kinesin and dynein normally carry cargo directionally along microtubules." }, { "id": "cells-vesicle-cytoskeleton-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "A learner records that long-distance vesicle transport inside the cell slows. Which preceding event best accounts for it?", "options": [ "Ribosomal RNA synthesis in the nucleolus is inhibited", "Motor proteins are prevented from moving along cytoskeletal tracks", "Catalase is absent from peroxisomes", "The nucleus retains intact DNA and functional transcription machinery" ], "answer": 1, "explanation": "Long-distance vesicle transport inside the cell slows. Kinesin and dynein normally carry cargo directionally along microtubules." }, { "id": "cells-vesicle-cytoskeleton-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After motor proteins are prevented from moving along cytoskeletal tracks, which explanation best links the change to its outcome?", "options": [ "The nucleolus normally combines rRNA with imported ribosomal proteins", "Catalase normally converts the reactive peroxide into water and oxygen", "Kinesin and dynein normally carry cargo directionally along microtubules", "Genes serve as templates for transcription before ribosomes translate the messages" ], "answer": 2, "explanation": "Long-distance vesicle transport inside the cell slows. Kinesin and dynein normally carry cargo directionally along microtubules." }, { "id": "cells-vesicle-cytoskeleton-integrated", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: motor proteins are prevented from moving along cytoskeletal tracks?", "options": [ "The cell can produce RNA instructions for protein synthesis — Genes serve as templates for transcription before ribosomes translate the messages", "Production of new ribosomal subunits declines — The nucleolus normally combines rRNA with imported ribosomal proteins", "Hydrogen peroxide can accumulate and damage the cell — Catalase normally converts the reactive peroxide into water and oxygen", "Long-distance vesicle transport inside the cell slows — Kinesin and dynein normally carry cargo directionally along microtubules" ], "answer": 3, "explanation": "Long-distance vesicle transport inside the cell slows. Kinesin and dynein normally carry cargo directionally along microtubules." }, { "id": "cells-nucleolus-inhibition-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "A student models this change: Ribosomal RNA synthesis in the nucleolus is inhibited. What should the model predict first?", "options": [ "Production of new ribosomal subunits declines", "The cell can produce RNA instructions for protein synthesis", "Hydrogen peroxide can accumulate and damage the cell", "A polypeptide can be assembled in the encoded amino-acid sequence" ], "answer": 0, "explanation": "Production of new ribosomal subunits declines. The nucleolus normally combines rRNA with imported ribosomal proteins." }, { "id": "cells-nucleolus-inhibition-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "What is the most likely cause when production of new ribosomal subunits declines?", "options": [ "Catalase is absent from peroxisomes", "Ribosomal RNA synthesis in the nucleolus is inhibited", "A ribosome binds an mRNA molecule", "The nucleus retains intact DNA and functional transcription machinery" ], "answer": 1, "explanation": "Production of new ribosomal subunits declines. The nucleolus normally combines rRNA with imported ribosomal proteins." }, { "id": "cells-nucleolus-inhibition-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After ribosomal RNA synthesis in the nucleolus is inhibited, which explanation best links the change to its outcome?", "options": [ "Genes serve as templates for transcription before ribosomes translate the messages", "Catalase normally converts the reactive peroxide into water and oxygen", "The nucleolus normally combines rRNA with imported ribosomal proteins", "The ribosome coordinates codon recognition and peptide-bond formation" ], "answer": 2, "explanation": "Production of new ribosomal subunits declines. The nucleolus normally combines rRNA with imported ribosomal proteins." }, { "id": "cells-nucleolus-inhibition-integrated", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: ribosomal RNA synthesis in the nucleolus is inhibited?", "options": [ "Hydrogen peroxide can accumulate and damage the cell — Catalase normally converts the reactive peroxide into water and oxygen", "A polypeptide can be assembled in the encoded amino-acid sequence — The ribosome coordinates codon recognition and peptide-bond formation", "The cell can produce RNA instructions for protein synthesis — Genes serve as templates for transcription before ribosomes translate the messages", "Production of new ribosomal subunits declines — The nucleolus normally combines rRNA with imported ribosomal proteins" ], "answer": 3, "explanation": "Production of new ribosomal subunits declines. The nucleolus normally combines rRNA with imported ribosomal proteins." }, { "id": "cells-peroxisome-catalase-outcome", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: Catalase is absent from peroxisomes?", "options": [ "Hydrogen peroxide can accumulate and damage the cell", "A polypeptide can be assembled in the encoded amino-acid sequence", "Its rough endoplasmic reticulum becomes especially prominent", "The cell can produce RNA instructions for protein synthesis" ], "answer": 0, "explanation": "Hydrogen peroxide can accumulate and damage the cell. Catalase normally converts the reactive peroxide into water and oxygen." }, { "id": "cells-peroxisome-catalase-cause", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: hydrogen peroxide can accumulate and damage the cell?", "options": [ "The nucleus retains intact DNA and functional transcription machinery", "Catalase is absent from peroxisomes", "A ribosome binds an mRNA molecule", "A cell begins secreting large quantities of protein" ], "answer": 1, "explanation": "Hydrogen peroxide can accumulate and damage the cell. Catalase normally converts the reactive peroxide into water and oxygen." }, { "id": "cells-peroxisome-catalase-mechanism", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "After catalase is absent from peroxisomes, which explanation best links the change to its outcome?", "options": [ "Genes serve as templates for transcription before ribosomes translate the messages", "The ribosome coordinates codon recognition and peptide-bond formation", "Catalase normally converts the reactive peroxide into water and oxygen", "Attached ribosomes synthesize proteins that enter the endomembrane pathway" ], "answer": 2, "explanation": "Hydrogen peroxide can accumulate and damage the cell. Catalase normally converts the reactive peroxide into water and oxygen." }, { "id": "cells-peroxisome-catalase-integrated", "chapter": "Cell Structure & Function", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: catalase is absent from peroxisomes?", "options": [ "The cell can produce RNA instructions for protein synthesis — Genes serve as templates for transcription before ribosomes translate the messages", "A polypeptide can be assembled in the encoded amino-acid sequence — The ribosome coordinates codon recognition and peptide-bond formation", "Its rough endoplasmic reticulum becomes especially prominent — Attached ribosomes synthesize proteins that enter the endomembrane pathway", "Hydrogen peroxide can accumulate and damage the cell — Catalase normally converts the reactive peroxide into water and oxygen" ], "answer": 3, "explanation": "Hydrogen peroxide can accumulate and damage the cell. Catalase normally converts the reactive peroxide into water and oxygen." }, { "chapter": "Cell Structure & Function", "id": "applied-magnification", "difficulty": "Standard", "stem": "A cell image is 36 mm long. The actual cell is 60 μm long. What is the magnification?", "options": [ "×600", "×60", "×2,160", "×6,000" ], "answer": 0, "explanation": "Convert 36 mm to 36,000 μm, then divide image size by actual size: 36,000 ÷ 60 = 600." }, { "chapter": "Cell Structure & Function", "id": "applied-surface-ratio", "difficulty": "Challenge", "stem": "A cubic cell doubles its side length. How does its surface-area-to-volume ratio change?", "options": [ "It doubles", "It halves", "It quadruples", "It is unchanged" ], "answer": 1, "explanation": "Surface area scales with length squared but volume with length cubed. Doubling length gives four times the area and eight times the volume, halving their ratio." }, { "chapter": "Cell Structure & Function", "id": "applied-secretory-tracer", "difficulty": "Standard", "stem": "A labelled amino acid becomes part of a protein that is secreted from an animal cell. Which route is most consistent with this observation?", "options": [ "Free ribosome → nucleus → lysosome", "Smooth ER → mitochondrion → Golgi apparatus", "Rough ER → Golgi apparatus → secretory vesicle", "Golgi apparatus → nucleolus → peroxisome" ], "answer": 2, "explanation": "Proteins entering the secretory pathway are synthesized into rough ER, modified and sorted through the Golgi, then carried in vesicles to the plasma membrane." }, { "chapter": "Cell Structure & Function", "id": "applied-transport-evidence", "difficulty": "Challenge", "stem": "A solute is more concentrated inside a cell than outside. Uptake continues against this gradient but falls when ATP production is inhibited. Which conclusion is best supported?", "options": [ "The solute enters only by simple diffusion", "The solute crosses only through the lipid bilayer", "The membrane has become freely permeable to all ions", "Uptake depends on energy, directly or through a maintained gradient" ], "answer": 3, "explanation": "Movement against a concentration gradient requires an energy source. ATP inhibition supports energy-dependent transport but does not distinguish direct ATP use from secondary active transport." } ] }