1. Transport across membranes (lesson before half term)

2. Bell task: Transport across membranes
Concentration gradient
Energy (ATP)
Simple diffusion
Down (high to low)
Facilitated diffusion
yes
Active transport

3. Bell task: Transport across membranes
Concentration gradient
Energy (ATP)
Carrier protein
Simple diffusion
Down (high to low) N
Facilitated diffusion
yes
Active transport
Against (Low to high) Y

4. Explain the rate of release
Carrots!
Explain the rate of release
of ions between
35 and 45 °C
50 and 60 °C
Rate of release of chloride ions from carrot discs in water
Temperature (°C)

5. Carrot answers
(a) Between 35 and 45 °C there is a small linear increase in the rate of release of chloride ions. This is due to the increased KE of these ions and they are diffusing out of the cells.
Rate of release of chloride ions from carrot discs in water
Temperature (°C)

6. Carrot answers Thermal death point of the cell
(b) Between 50 and 60 °C there is a rapid increase in the rate of release of chloride ions. This is due to the high temperatures denaturing the proteins in the cell membrane.
Rate of release of chloride ions from carrot discs in water
Temperature (°C)

7. Why does the graph level off
Carrots!
Why does the graph level off
above 60 C?
Rate of release of chloride ions from carrot discs in water
Temperature (°C)

8. Carrots! Why does the graph level off above 60 C?
Max membrane damage has occurred.
Or equilibrium reached in terms
of ions inside
and outside
Rate of release of chloride ions from carrot discs in water
Temperature (°C)

9. Beetroot ISA graphs. Peer assess using a green pen (max 5)
Independent var on x axis (concentration of alcohol) and dependent var on y axis. (1 mark)
Both axes correctly labeled with headings and units (1 mark)…
Concentration of alcohol / %
Absorbance of beetroot solution / arbitrary units
Appropriate scales (for accurate plotting and reading of scales. ( 1 mark)
All points plotted correctly (to within ½ square) (1 mark)
Data as line graph (1 mark)
Points joined with a curve of best fit if it is felt intermediate values will fall on such a curve.
Alternatively all points joined with straight lines if the position of intermediate points cannot be predicted reliably.
No marks if curve extrapolates beyond line
Title: The effect of alcohol concentration on pigment loss from beetroot cells

10. Swap books Using GREEN pens peer assess beetroot ISA questions
For each answer underline or highlight the mark scheme where marks have not been awarded.

11. To do Beetroot ISA section A exam questions
Complete then mark using the mark scheme

12. Beetroot ISA Approx’ grade MAX 17 (SECTION A) A 14 B 13 C 12 D 11 E 10
Add your approx’ grade
IN GREEN PEN
Self evaluation:
Try and summarise two facts or tips you have learnt from this task (can include ideas from graph/table section from last week).

13. To do
Transport across membranes question 7

15. 7. a) Explain one piece of evidence from the graph that shows the uptake of chloride ions by roots is by active transport. (1 mark)
(b) Explain the shape of the curve for 18 °C. (2 marks)
(c) Explain the difference in the rate of uptake for 4 °C and 18 °C. (2 marks)

16. ANSWERS
Question 7
(a) Idea of uptake against a concentration gradient; 1
(b) Reference to carriers;
No further increase (in rate) when all proteins / carriers in use / carriers saturated / carriers limiting; 2
(reject carriers used up)
(c) Rate of respiration increases;
So more ATP produced / energy released (for active uptake);
More chance of collision with carriers (due to higher kinetic energy); 2 max
Total 5

17. Half term HW Transport across membranes summary map.
Add corrections from website in another colour.
Do some further self study to consolidate what you have learnt this half term (next test in a couple of weeks).
Collect your book from the filing cabinet from Wednesday onwards.
Act on any areas on weakness from last HW to improve