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United StatesBiology

Unit 2: Cell Structure and Function

11 dot points across 11 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does internal compartmentalization improve the efficiency of eukaryotic cells?

Topic 2.10 Cell Compartmentalization: explain how internal membranes and membrane-bound organelles contribute to the compartmentalization of eukaryotic cell functions.
A focused answer to AP Biology Topic 2.10, covering how internal membranes and organelles compartmentalize eukaryotic functions, the advantages of separating incompatible reactions, and how this raises efficiency.
9 min answer →

Why does the surface-area-to-volume ratio limit cell size and shape the efficiency of exchange?

Topic 2.3 Cell Size: explain the effect of surface-area-to-volume ratios on the exchange of materials between cells or organisms and the environment.
A focused answer to AP Biology Topic 2.3, covering why surface-area-to-volume ratio limits cell size, how it affects the rate of exchange, and adaptations that increase surface area, with full worked calculations.
10 min answer →

How does the structure of a cell and its organelles relate to the functions the cell performs?

Topic 2.2 Cell Structure and Function: explain how subcellular structures and organelles provide essential functions and how structure relates to function in cells.
A focused answer to AP Biology Topic 2.2, covering how subcellular structures provide essential functions, the structure-to-function relationship, and how specialized cells reflect their roles, with worked exam practice.
9 min answer →

What are the subcellular components of cells and how do their structures suit their functions?

Topic 2.1 Cell Structure: Subcellular Components: describe the structures and functions of the subcellular components and organelles of prokaryotic and eukaryotic cells.
A focused answer to AP Biology Topic 2.1, covering the organelles of eukaryotic cells (nucleus, ribosomes, ER, Golgi, mitochondria, chloroplasts, lysosomes, vacuoles) and the endomembrane system, with structure-to-function reasoning.
10 min answer →

How do channel and carrier proteins move polar molecules and ions across the membrane without energy?

Topic 2.7 Facilitated Diffusion: explain how the structure of channel and carrier proteins allows the facilitated diffusion of polar molecules and ions across a membrane.
A focused answer to AP Biology Topic 2.7, covering facilitated diffusion through channel and carrier proteins, aquaporins, why it is passive, and how it differs from simple diffusion and active transport.
9 min answer →

How does active transport build and use electrochemical gradients, and how does bulk transport move large material?

Topic 2.9 Mechanisms of Transport: explain how active transport and bulk transport move ions and large molecules across membranes and establish electrochemical gradients.
A focused answer to AP Biology Topic 2.9, covering active transport, the sodium-potassium pump, electrochemical gradients, secondary active transport, and bulk transport by endocytosis and exocytosis.
9 min answer →

How does the structure of the membrane determine which substances can cross it?

Topic 2.5 Membrane Permeability: explain how the structure of biological membranes influences selective permeability.
A focused answer to AP Biology Topic 2.5, covering selective permeability, why the phospholipid bilayer blocks polar and charged substances, the factors affecting permeability, and the role of transport proteins.
9 min answer →

How do passive and active transport move substances across the membrane, and how do they differ in energy use?

Topic 2.6 Membrane Transport: describe the mechanisms that organisms use to transport large and small molecules across the membrane and the energy requirements of passive and active transport.
A focused answer to AP Biology Topic 2.6, covering passive transport (diffusion and osmosis) versus active transport, the role of concentration gradients and ATP, and bulk transport by endocytosis and exocytosis.
9 min answer →

How did membrane-bound organelles such as mitochondria and chloroplasts arise?

Topic 2.11 Origins of Cell Compartmentalization: describe the similarities and differences in compartmentalization between prokaryotic and eukaryotic cells, and the evidence for the endosymbiotic origin of mitochondria and chloroplasts.
A focused answer to AP Biology Topic 2.11, covering the endosymbiotic theory, the evidence that mitochondria and chloroplasts descend from free-living prokaryotes, and the origin of the endomembrane system.
9 min answer →

How does the fluid-mosaic structure of the plasma membrane suit its role at the cell boundary?

Topic 2.4 Plasma Membranes: describe the roles of each of the components of the cell membrane in maintaining the internal environment of the cell.
A focused answer to AP Biology Topic 2.4, covering the fluid-mosaic model, the phospholipid bilayer, membrane proteins, cholesterol and carbohydrates, and how each component maintains the cell's internal environment.
9 min answer →

How does tonicity determine the movement of water, and how do organisms osmoregulate?

Topic 2.8 Tonicity and Osmoregulation: explain how concentration gradients of water and solutes affect the movement of water into and out of cells, and how organisms regulate their water balance.
A focused answer to AP Biology Topic 2.8, covering hypotonic, hypertonic and isotonic solutions, osmosis, water potential, and how cells and organisms osmoregulate, with full worked water-potential calculations.
10 min answer →