Active Transport
Cells use ATP to move substances against a gradient.
About this topic
Active transport moves substances across a membrane against their concentration gradient, from low to high, and requires energy from ATP and carrier proteins. Examples: root hair cells absorbing mineral ions from soil, glucose uptake in the intestine and kidney, and the sodium–potassium pump in nerves.
Cells doing lots of active transport have many mitochondria. If respiration stops, active transport stops. Unlike diffusion, it can build up high concentrations inside cells.
Root hair cells show the idea well: soil has fewer nitrate ions than the root cell, yet the plant needs them, so carrier proteins use ATP to pump nitrates in against the gradient. In your small intestine, glucose is absorbed the same way when concentrations in the gut become lower than in the blood, so you do not lose valuable nutrients. Nerve cells use the sodium-potassium pump to maintain their electrical charge.
Because the process needs ATP, cells with lots of active transport, like kidney tubule cells, contain many mitochondria. A good test question: if oxygen or a respiratory poison is removed and uptake stops, that suggests active transport. Students often confuse it with facilitated diffusion, which also uses carrier proteins but moves substances down their gradient with no energy.
Key ideas
- Carrier proteins
- Used by root hair cells
- Needs mitochondria
Quick check
Use cases: where Active Transport helps
- Homework: review the key idea behind Active Transport before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Active Transport without notes.
- Visual learning: play with the interactive lab to see how Active Transport changes when you adjust its inputs.
- Teaching a friend: explain Active Transport in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Active Transport?
Cells use ATP to move substances against a gradient.
What will I learn in Active Transport?
Carrier proteins. Used by root hair cells. Needs mitochondria.
Is Active Transport part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Active Transport lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Active Transport?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.