Transcript Transport across membranes (lesson before half term)

Transport across membranes
(lesson before half term)
Bell task: Transport across membranes
Transport
Simple
diffusion
Facilitated
diffusion
Active
transport
Concentration Energy
gradient
(ATP)
Down (high to
low)
yes
Bell task: Transport across membranes
Transport
Concentration
gradient
Simple
Down (high to
diffusion
low)
Facilitated Down (high to
diffusion
low)
Active
Against (Low
transport to high)
Energy Carrier
(ATP) protein
N
N
N
yes
Y
Y
Carrots!
Rate of
release of
chloride
ions from
carrot discs
in water
Explain the rate of release
of ions between
(a) 35 and 45 °C
(b) 50 and 60 °C
35 40 45 50 55 60 65 70
Temperature (°C)
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
35 40 45 50 55 60 65 70
Temperature (°C)
Carrot answers
Thermal death
point of the cell
Rate of
release of
chloride
ions from
carrot discs
in water
35 40 45 50 55 60 65 70
Temperature (°C)
(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.
Carrots!
Rate of
release of
chloride
ions from
carrot discs
in water
Why does the graph level off
above 60 C?
35 40 45 50 55 60 65 70
Temperature (°C)
Carrots!
Rate of
release of
chloride
ions from
carrot discs
in water
Why does the graph level off
above 60 C?
Max membrane damage has occurred.
Or equilibrium reached in terms
of ions inside
and outside
35 40 45 50 55 60 65 70
Temperature (°C)
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)…
i. Concentration of alcohol / %
ii. 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)
i. Points joined with a curve of best fit if it is felt intermediate values will fall on such
a curve.
ii. Alternatively all points joined with straight lines if the position of intermediate
points cannot be predicted reliably.
iii. No marks if curve extrapolates beyond line
Title: The effect of alcohol concentration on pigment loss from beetroot cells
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.
To do
• Beetroot ISA section A exam questions
• Complete then mark using the mark scheme
Beetroot ISA
Approx’ grade
A
B
C
D
MAX 17 (SECTION A)
14
13
12
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).
To do
• Transport across membranes question 7
• 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)
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
•
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