Active transport · Year 11
In Year 11 you get fluent with: active transport; active transport in root hairs and the gut.
Active transport moves substances from a more dilute solution to a more concentrated one, against the concentration gradient. It uses carrier proteins in the cell membrane and needs energy from respiration. Root hair cells take in mineral ions from the soil this way, and the gut absorbs sugar into blood that already has more sugar.
Key facts
- Active transport moves substances from a more dilute solution to a more concentrated solution, against the concentration gradient. It needs energy from respiration. Root hair cells take in mineral ions this way, and the gut absorbs sugar into the blood.
- Cells that do a lot of active transport, such as root hair cells, have many mitochondria to release the energy it needs.
Worked examples
Example 1
What is active transport?
Answer: the movement of substances from a more dilute solution to a more concentrated solution, using energy from respiration
Example 2
Which process is this: the movement of substances from a more dilute solution to a more concentrated solution, using energy from respiration?
Answer: active transport
Example 3
Which process moves substances in this example: mineral ions moving from very dilute soil water into a root hair cell?
Answer: active transport
Example 4
Which process moves substances in this example: sugar moving from the gut into blood that already has a higher sugar concentration?
Answer: active transport
Example 5
Root hair cells take in mineral ions from the soil. Explain why they use active transport, and why they have many mitochondria.
Answer: the ions are more concentrated inside the cell than in the soil, so they must be moved against the gradient using energy from respiration, which happens in mitochondria
Example 6
A poison stops respiration in root hair cells. Why do they stop taking in mineral ions, but still take in water?
Answer: Mineral ions come in by active transport, which needs energy from respiration; water comes in by osmosis, which needs no energy.