1. Starter: Select the ions from this list:
Active transport and facilitated diffusion.
Starter: Select the ions from this list:
Extension: Identify this specialised cell. Where can you find it? How is it adapted to carry out its function?
Mg, Mg+2,K+,K, NO-3,HNO3, PO-34
How do you know they are ions?

2. Active transport and facilitated diffusion.
WALT:
State examples of where facilitated diffusion happens in living organisms.
Describe the process of active transport.
Explain the use of energy in active transport
Evaluate the model of membrane channels in active transport.

3. Cell membranes, polarity and diffusion
Boardworks AS Biology
Transport Across Membranes
Cell membranes, polarity and diffusion
The non-polar, hydrophobic tails of phospholipid molecules in a cell membrane act as a barrier to most substances.
Generally, the smaller and less polar a molecule, the easier and faster it will diffuse across a cell membrane.
Small, non-polar molecules such as oxygen and carbon dioxide rapidly diffuse across a membrane.
Small, polar molecules, such as water and urea, also diffuse across, but much more slowly.
Charged particles (ions) cannot diffuse across a membrane, even if they are very small.

4. Facilitated diffusion
Boardworks AS Biology
Transport Across Membranes
Facilitated diffusion
Teacher notes
Ions travel down an electrochemical gradient, rather than a concentration gradient.

5. Introduction. When to use active transport?

6. Moving substances by active transport
Active transport allows cells to move substances from an area of low concentration to an area of high concentration.
This movement is against the concentration gradient. As a result, cells can absorb ions from very dilute solutions.
It also enables cells to move substances, such as sugars and ions, from one place to another through the cell membrane.
Energy is needed to carry a molecule across the membrane and then return to its original position. This energy is released during cell respiration. So if a cell respires and releases a lot energy, it can carry out lots of active transport.
Cells involved in active transport usually have many mitochondria to release the energy they need.
Examples:
Root hair cells in plants
Cell lining in your gut

7. The importance of active transport
Widely used in cells!
There are situations where AT is particularly important:
Mineral ions in the soil ( e.g. nitrate ions) are usually found in very dilute solutions. These solutions are more dilute than the solution within the plant root hair cells. By using active transport, plant can use these ions, even though is against the concentration gradient.
Sugar (e.g glucose) is always actively absorbed out of your gut and kidney tubules into your blood. This is often done against a large concentration gradient. Glucose is needed for cell respiration so it is important to get as much as possible out of the gut. When this happens, AT is used to move the glucose from your gut into your blood against the concentration gradient.

8. Visualise it

10. Check your answers

11. Literacy

12. Check your answers

13. Practise

14. Check someone’s answers

15. extras

16. Wordsearch
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18. Transport across the membranes -Review?