--- title: "AP Biology Unit 2 Practice Test" description: "A timed AP Biology Unit 2 (Cells) practice test in the AP format, drawn from 3,661 multiple-choice questions and 82 FRQs written for the unit. The standard version takes about 60 minutes." canonical: "https://fiveable.me/ap-bio/unit-test/2" type: "unit-test" subject: "AP Biology" unit: "Unit 2" --- # AP Biology Unit 2 Practice Test ## Overview A timed AP Biology Unit 2 (Cells) practice test in the AP format, drawn from 3,661 multiple-choice questions and 82 FRQs written for the unit. The standard version takes about 60 minutes. ## Test Format - 20 Multiple Choice Questions (30 minutes) - 1 FRQ – FRQ 1 – Interpreting and Evaluating Experimental Results (Long) (15 minutes) - 1 FRQ – FRQ 3 – Scientific Investigation (Short) (15 minutes) ## Unit FRQs by Type - [FRQ 1 – Interpreting and Evaluating Experimental Results (Long)](/ap-bio/frqs/experimental-results?unit=2): 11 questions - [FRQ 2 – Interpreting and Evaluating Experimental Results with Graphing (Long)](/ap-bio/frqs/graphing?unit=2): 7 questions - [FRQ 3 – Scientific Investigation (Short)](/ap-bio/frqs/scientific-investigation?unit=2): 17 questions - [FRQ 4 – Conceptual Analysis (Short)](/ap-bio/frqs/conceptual-analysis?unit=2): 18 questions - [FRQ 5 – Analyze Model or Visual Representation (Short)](/ap-bio/frqs/model-analysis?unit=2): 12 questions - [FRQ 6 – Analyze Data (Short)](/ap-bio/frqs/data-analysis?unit=2): 17 questions ## Practice Questions ### Question 1 A liver cell takes up low-density lipoprotein (LDL) particles by binding them to specific surface receptors and internalizing the membrane as a coated vesicle. What model best represents the mechanism moving LDL across the plasma membrane? - (A) Receptor binding triggers coated pits, forming vesicles that import intact LDL - (B) ATP-driven pumps move intact LDL through a transport protein in the bilayer - (C) A ligand-gated channel opens, allowing intact LDL to diffuse into cytosol - (D) LDL dissolves in the lipid bilayer and crosses directly by simple diffusion **Answer: (A)** Linking receptor specificity with vesicle formation shows receptor-mediated endocytosis. The cell internalizes LDL as an intact particle inside a coated vesicle rather than moving it through a channel. ### Question 2 A protozoan engulfs an entire bacterium by extending its membrane around the bacterium and forming an internal vesicle. Which sequence best models the transport pathway for this large particle across the plasma membrane? - (A) Membrane surrounds bacterium, vesicle pinches inward, lysosome fuses to digest - (B) Bacterium binds receptors, clathrin vesicle forms, then lysosomes digest the cargo - (C) Bacterium enters through a channel, then ribosomes digest it into usable monomers - (D) Bacterium diffuses across the phospholipids, then is broken down in cytosol **Answer: (A)** Mapping a particle being engulfed to vesicle formation identifies phagocytosis. The follow-up fusion with lysosomes explains how the internalized bacterium is processed after membrane transport. ### Question 3 A secretory cell releases a large glycoprotein hormone to the bloodstream after the hormone is packaged in Golgi-derived vesicles. What model best represents how the hormone crosses the plasma membrane to exit the cell? - (A) Vesicles dock and fuse with membrane, releasing glycoprotein to extracellular fluid - (B) The glycoprotein crosses by a carrier that flips it across the bilayer intact - (C) A channel opens during stimulation, letting the glycoprotein flow out by diffusion - (D) The glycoprotein dissolves in lipids and exits directly through the membrane core **Answer: (A)** Connecting vesicle trafficking with membrane fusion identifies exocytosis. The glycoprotein remains intact inside the vesicle until fusion releases it outside the cell. ### Question 4 A cell biologist creates a flowchart showing how a protein hormone enters a target cell. The flowchart includes steps for receptor binding, membrane invagination, vesicle formation, and vesicle fusion with lysosomes. Which transport mechanism does this flowchart represent? - (A) Receptor-mediated endocytosis, which uses specific membrane proteins to selectively internalize large molecules into vesicles - (B) Phagocytosis, which uses specific membrane proteins to selectively internalize large molecules through pseudopod extension - (C) Pinocytosis, which uses nonspecific membrane folding to randomly internalize large molecules into vesicles for processing - (D) Exocytosis, which uses specific membrane proteins to selectively release large molecules from vesicles into extracellular space **Answer: (A)** Identifying the sequence of receptor binding followed by vesicle formation reveals receptor-mediated endocytosis. This mechanism allows cells to selectively import specific large molecules like hormones by using receptor proteins that trigger membrane invagination upon ligand binding. ### Question 5 A pancreatic acinar cell synthesizes digestive enzymes for secretion. The cell's compartments are numbered as follows: (1) rough endoplasmic reticulum, (2) Golgi apparatus, (3) secretory vesicles, and (4) plasma membrane. Which sequence correctly represents the exocytosis pathway for these large protein molecules? - (A) Proteins move through compartments 1→2→3→4, with vesicle fusion at the membrane releasing enzymes to the exterior - (B) Proteins move through compartments 2→1→3→4, with vesicle fusion at the membrane releasing enzymes to the exterior - (C) Proteins move through compartments 1→3→2→4, with vesicle fusion at the membrane releasing enzymes to the exterior - (D) Proteins move through compartments 1→2→4→3, with vesicle fusion at the membrane releasing enzymes to the exterior **Answer: (A)** Tracing the secretory pathway requires understanding organelle relationships in protein export. Digestive enzymes are synthesized at the rough ER, modified in the Golgi, packaged into secretory vesicles, and released when vesicles fuse with the plasma membrane during exocytosis. ### Question 6 A systems diagram of a macrophage shows three distinct pathways for internalizing materials: pathway A engulfs a bacterium using membrane extensions, pathway B forms small vesicles continuously from membrane regions, and pathway C shows clathrin-coated pits forming after ligand binding. Which statement correctly describes the relationship between these pathways? - (A) All three pathways use membrane-derived vesicles for transport, but only pathway C demonstrates selectivity for specific molecules - (B) All three pathways use membrane-derived vesicles for transport, but only pathway A demonstrates selectivity for specific molecules - (C) Only pathways A and C use membrane-derived vesicles, while pathway B transports molecules directly through membrane channels - (D) All three pathways use membrane-derived vesicles for transport, but only pathway B demonstrates selectivity for specific molecules **Answer: (A)** Analyzing the systems diagram requires distinguishing selective from nonselective endocytosis. Phagocytosis (A) and pinocytosis (B) are relatively nonspecific, while receptor-mediated endocytosis (C) with clathrin-coated pits selectively imports molecules that bind specific receptors. ### Question 7 A mathematical model predicts vesicle formation rate during endocytosis using the equation R = k[receptor][ligand], where R is rate, k is a constant, and brackets indicate concentration. If receptor concentration doubles while ligand concentration is halved, how does this model predict the vesicle formation rate will change? - (A) The rate remains unchanged because the doubling and halving effects cancel each other in the multiplicative relationship - (B) The rate increases fourfold because receptor concentration has a squared effect on the multiplicative relationship - (C) The rate decreases by half because ligand concentration is the limiting factor in the multiplicative relationship - (D) The rate increases twofold because receptor concentration changes have greater effects than ligand concentration changes **Answer: (A)** Applying the mathematical model requires understanding how variables interact multiplicatively. When receptor concentration doubles (2×) and ligand concentration halves (0.5×), the product remains constant: 2 × 0.5 = 1, so R stays the same. ### Question 8 A flowchart depicts insulin secretion from a beta cell with the following steps: glucose enters cell → ATP production increases → potassium channels close → membrane depolarizes → calcium channels open → vesicles fuse with membrane. Which component of this model directly enables the transport of insulin across the plasma membrane? - (A) Vesicle fusion with the plasma membrane, which releases insulin through exocytosis without requiring the hormone to pass through the lipid bilayer - (B) Calcium channel opening at the plasma membrane, which creates pores large enough for insulin molecules to diffuse through directly - (C) Potassium channel closing at the plasma membrane, which traps insulin inside until membrane depolarization forces release through the channels - (D) ATP production increase in the cytoplasm, which provides energy for active transport of insulin directly through membrane carrier proteins **Answer: (A)** Identifying the transport mechanism requires tracing the flowchart to its final step. Exocytosis allows large molecules like insulin to exit the cell when secretory vesicle membranes merge with the plasma membrane, releasing contents extracellularly. ### Question 9 A cell biologist models the transport of insulin across the plasma membrane of a target cell. Insulin, a large protein hormone, binds to a receptor on the cell surface, triggering the formation of a vesicle that brings the insulin-receptor complex into the cell. Which diagram would best represent this transport mechanism? - (A) A flowchart showing receptor binding, membrane invagination forming a coated pit, vesicle formation, and release of insulin into the cytoplasm - (B) A flowchart showing receptor binding, conformational change opening a channel, and direct passage of insulin through the membrane protein - (C) A flowchart showing insulin diffusing through the lipid bilayer, binding to an internal receptor, and triggering a cellular response - (D) A flowchart showing receptor binding, ATP hydrolysis pumping insulin across the membrane, and release on the cytoplasmic side **Answer: (A)** Representing receptor-mediated endocytosis requires showing the sequential steps: receptor binding triggers membrane invagination, forming a coated pit that pinches off into a vesicle, delivering the large molecule into the cell. This captures the mechanism organisms use to transport large molecules like insulin across the membrane. ### Question 10 Researchers studying phagocytosis in white blood cells create a mathematical model to predict the rate of bacterial uptake. The model includes variables for pseudopod extension rate ($$r$$), bacterial binding affinity ($$k$$), and membrane available for engulfment ($$A$$). Which relationship would best represent how these variables affect the rate of phagocytosis ($$P$$)? - (A) $$P = k \cdot r \cdot A$$, showing phagocytosis rate increases proportionally when binding affinity, extension rate, and available membrane all increase - (B) $$P = k + r + A$$, showing phagocytosis rate increases additively when binding affinity, extension rate, and available membrane all increase - (C) $$P = \frac{k \cdot r}{A}$$, showing phagocytosis rate increases with binding affinity and extension rate but decreases as available membrane increases - (D) $$P = k \cdot r \cdot A^2$$, showing phagocytosis rate increases exponentially with available membrane while remaining proportional to binding affinity and extension rate **Answer: (A)** Modeling phagocytosis as a transport mechanism requires representing how multiple factors combine to determine uptake rate. Higher binding affinity increases bacterial capture, faster pseudopod extension speeds engulfment, and more available membrane allows simultaneous uptake events, making their product proportional to overall phagocytosis rate. ## Review the Unit - [2.1 Cell Structure and Function](/ap-bio/unit-2/cell-structure-subcellular-components/study-guide/oFM5gT3D8Pj5lZXmTNB9) - [2.2 Cell Size](/ap-bio/unit-2/cell-structure-function/study-guide/znjrRPCY6596o2nWt05n) - [2.3 Plasma Membrane](/ap-bio/unit-2/cell-size/study-guide/3oB8hJyGwvYACz8XlUmG) - [2.4 Membrane Permeability](/ap-bio/unit-2/plasma-membranes/study-guide/1aW0ZDGzS56ism3BJwTi) - [2.5 Membrane Transport](/ap-bio/unit-2/membrane-permeability/study-guide/1114cAD5d5VyivEBDKDJ) - [2.6 Facilitated Diffusion](/ap-bio/unit-2/membrane-transport/study-guide/7yV52dtD7Vj7ZadTEd2P) - [2.7 Tonicity and Osmoregulation](/ap-bio/unit-2/tonicity-osmoregulation/study-guide/i3qUckt9PGfT4pQlHq5B) - [2.8 Mechanisms of Transport](/ap-bio/unit-2/mechanisms-of-transport/study-guide/CCENUydXNVb7K4P7ikp7) - [2.9 Cell Compartmentalization](/ap-bio/unit-2/mechanisms-transport/study-guide/sMlGCA9J4sGVE7S24xBM) - [2.10 Origins of Cell Compartmentalization](/ap-bio/unit-2/cell-compartmentalization/study-guide/HRfoDYQgTXrvyzemUlwu) - [Origins of Cell Compartmentalization Review](/ap-bio/unit-2/origins-of-compartmentalization/study-guide/GC84zJJwIDYFWwSzFPNy) ## Other Unit Tests - [Unit 1: Chemistry of Life](/ap-bio/unit-test/1) - [Unit 3: Cellular Energetics](/ap-bio/unit-test/3) - [Unit 4: Cell Communication and Cell Cycle](/ap-bio/unit-test/4) - [Unit 5: Heredity](/ap-bio/unit-test/5) - [Unit 6: Gene Expression and Regulation](/ap-bio/unit-test/6) - [Unit 7: Natural Selection](/ap-bio/unit-test/7) - [Unit 8: Ecology](/ap-bio/unit-test/8) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`)