AP Biology · Unit 2: Cells
2.6 Facilitated Diffusion
In short
You must understand that facilitated diffusion is a passive process requiring no energy input, where substances move down their concentration gradient. The topic specifically requires knowledge of transport and channel proteins for moving charged ions (such as Na+ and K+) and large polar molecules.
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What else do you need to know about Facilitated Diffusion?
You should know that ion movement can polarize membranes and must specifically recognize aquaporins as the channels responsible for transporting large quantities of water.
Can you do these?
- I can describe how charged ions require transport or channel proteins to move across the membrane, and how this movement can lead to membrane polarization.
- I can explain that facilitated diffusion moves large polar molecules down their concentration gradient without the input of energy.
- I can identify aquaporins as the specific proteins that transport large quantities of water across membranes.
How is Facilitated Diffusion tested on the exam?
The suggested skill for this topic is Argumentation (6.E), meaning you may be assessed on your ability to predict the causes or effects of a change in, or disruption to, one or more components in a biological system. Exam questions frequently ask you to predict the consequences of a mutated, blocked, or missing transport protein (e.g., an aquaporin or ion channel) on cell polarization, membrane permeability, or overall cellular homeostasis.
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Facilitated Diffusion: common questions
What do you need to know about Facilitated Diffusion for AP Biology?
You must understand that facilitated diffusion is a passive process requiring no energy input, where substances move down their concentration gradient. The topic specifically requires knowledge of transport and channel proteins for moving charged ions (such as Na+ and K+) and large polar molecules.
How is Facilitated Diffusion tested on the AP Biology exam?
The suggested skill for this topic is Argumentation (6.E), meaning you may be assessed on your ability to predict the causes or effects of a change in, or disruption to, one or more components in a biological system.
How do I know I have mastered Facilitated Diffusion?
Check you can do each of these: describe how charged ions require transport or channel proteins to move across the membrane, and how this movement can lead to membrane polarization; explain that facilitated diffusion moves large polar molecules down their concentration gradient without the input of energy; identify aquaporins as the specific proteins that transport large quantities of water across membranes.
Where does Facilitated Diffusion fit in AP Biology?
Facilitated Diffusion is topic 2.6 in Unit 2: Cells of AP Biology.
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