Data Qs Q1. A potometer is a piece of apparatus that can be used to measure water uptake by a leafy shoot. Figure 1 shows a potometer. Figure 1 Some students used a potometer like the one shown in Figure 1. • They measured the water taken up by a shoot in normal conditions in a classroom. • As the water was taken up by the shoot, the level of water in the capillary tube went down. • The students recorded the level of the water in the capillary tube at 2-minute intervals for 10 minutes. Table 1 shows the students’ results. Table 1 Time in minutes 0 2 4 6 8 10 Level of water (on scale) in 2.5 3.6 4.4 5.4 6.5 7.5
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Data Qs
Q1.A potometer is a piece of apparatus that can be used to measure water uptake by a leafy shoot.
Figure 1 shows a potometer.
Figure 1
Some students used a potometer like the one shown in Figure 1.
• They measured the water taken up by a shoot in normal conditions in a classroom.
• As the water was taken up by the shoot, the level of water in the capillary tube went down.
• The students recorded the level of the water in the capillary tube at 2-minute intervals for 10 minutes.
Table 1 shows the students’ results.
Table 1
Time in minutes 0 2 4 6 8 10
Level of water (on scale) incapillary tube in mm 2.5 3.6 4.4 5.4 6.5 7.5
The area of the cross section of the capillary tube was 0.8 mm2.
(a) (i) Complete the following calculation to find the volume of water taken up by the shoot in mm3 per minute.
Distance water moved along the scale in 10 minutes = ______ mm
Volume of water taken up by the shoot in 10 minutes = ______ mm3
Therefore, volume of water taken up by the shoot in 1 minute = ______ mm3
(3)
(ii) The students repeated the investigation but this time placed the potometer next to a fan blowing air over the leafy shoot.
Suggest how the results would be different. Give a reason for your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(b) The students repeated the investigation at different temperatures.
The results are shown in Table 2.
Table 2
Temperaturein °C
Rate of water uptakein mm3 per minute
10 0
15 0.4
20 1.0
25 2.1
30 3.2
35 4.0
40 4.4
Plot the data from Table 2 on the graph paper in Figure 2.
Choose suitable scales, label both axes and draw a line of best fit.
Figure 2
(5)
(c) What would happen to the leaves if the potometer was left for a longer time at 40 °C?
Explain your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
(Total 13 marks)
Q2.Photosynthesis needs light.
(a) Complete the balanced symbol equation for photosynthesis.
light6CO2 + _______________________ _______________________ + 6O2
(2)
(b) A green chemical indicator shows changes in the concentration of carbon dioxide (CO2) in a solution.
The indicator solution is green when the concentration of CO2 is normal.
The indicator solution turns yellow when the concentration of CO2 is high.
The indicator solution turns blue when the concentration of CO2 is very low or when there is no CO2.
The indicator solution does not harm aquatic organisms.
Students investigated the balance of respiration and photosynthesis using an aquatic snail and some pondweed.
The students set up four tubes, A, B, C and D, as shown in the table below.
The colour change in each tube, after 24 hours in the light, is recorded.
Tube A Tube B Tube C Tube D
Indicator solutiononly
Indicator solution+ pondweed
Indicator solution+ snail
Indicator solution+ pondweed
+ snail
Stays green Turns blue Turns yellow Stays green
(i) What is the purpose of Tube A?
______________________________________________________________
______________________________________________________________(1)
(ii) Explain why the indicator solution in Tube C turns yellow.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(iii) Predict the result for Tube D if it had been placed in the dark for 24 hours and not in the light.
Explain your prediction.
Prediction _____________________________________________________
______________________________________________________________
Explanation ____________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(3)
(Total 8 marks)
Q3.Students investigated the distribution of a green alga on a tree trunk.
The students:
• tied a piece of string horizontally round a tree
• put a quadrat on the string so that the quadrat faced south
• estimated the percentage of the area in the quadrat covered with the green alga
• repeated the observation with the quadrat facing south west, west, north west, north, north east, east and south east.
(a) The diagram shows the quadrat the students used.
Describe how you would estimate the percentage of the area covered with the green alga in one quadrat.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(b) The bar chart shows the students’ results.
Direction the quadrat faced
(i) How does the direction that the quadrat faced affect the percentage area covered with the green alga?
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) What was the mode of the percentage area covered with the green alga?
Mode = _________________________ %
Give the reason for your answer.
______________________________________________________________
______________________________________________________________(2)
(iii) Give three environmental factors that might affect the distribution of the green alga on the tree.
1. ____________________________________________________________
2. ____________________________________________________________
3. ____________________________________________________________(3)
(iv) Suggest how one of the factors you gave in part (b) (iii) might have caused the distribution of the green alga shown on the bar chart.
Factor _____________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
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______________________________________________________________(3)
(c) Nitrophyte lichens grow on the bark of trees. These lichens are indicators of air pollution by ammonia. Ammonia concentrations in the atmosphere are often high in agricultural areas.The graph shows the relationship between air quality and the distribution of nitrophyte lichens.
High atmospheric Low atmospheric ammonia ammonia
Air quality scores© U.S. Department of Agriculture
(i) Describe the relationship between atmospheric ammonia and the abundance of nitrophyte lichens.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) How useful would a particular value for the abundance of nitrophyte lichens be as an indicator of ammonia pollution of the atmosphere?Explain your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(Total 16 marks)
Q4.Infections by antibiotic resistant bacteria cause many deaths.
The bar chart below shows information about the number of deaths per year in England from Methicillin-resistant Staphylococcus aureus (MRSA) and from Clostridium difficile (C.difficile) over 4 years.
Year
(a) (i) Describe the trend for deaths caused by C.difficile.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) Suggest a reason for the trend you have described in part (a)(i).
Explain your answer.
______________________________________________________________
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______________________________________________________________(2)
(iii) Calculate the percentage change in deaths caused by MRSA from 2009 to 2010.
______________________________________________________________
______________________________________________________________
______________________________________________________________
Percentage change in deaths caused by MRSA = _______________ %(2)
(iv) Numbers have not yet been published for 2011.
When the numbers are published, scientists do not expect to see such a large percentage change from 2010 to 2011 as the one you have calculated for 2009 to 2010.
Suggest one reason why.
______________________________________________________________
______________________________________________________________(1)
(b) Before 2007 there was a rapid increase in the number of deaths caused by MRSA.
Describe how the overuse of the antibiotic methicillin led to this increase.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
(Total 10 marks)
Q5.Some students investigated the effect of pH on the digestion of boiled egg white by an enzyme called pepsin. Egg white contains protein.
The students:
• put a glass tube containing boiled egg white into a test tube
• added a solution containing pepsin at pH 7
• set up six more tubes with solutions of pepsin at different pH values
• left the test tubes for 24 hours at room temperature.
The image below shows one of the test tubes, at the start and at the end of the 24 hours.
At start 24 hours later
(a) (i) Name the product of protein digestion.
______________________________________________________________(1)
(ii) What type of enzyme digests protein?
Tick ( ) one box.
amylase
lipase
protease
(1)
(b) The egg white in each tube was 50 mm long at the start of the investigation. The table below shows the students’ results.
pH Length in mm of boiled egg white after 24 hours
1 38
2 20
3 34
4 45
5 50
6 50
7 50
(i) At which pH did the pepsin work best?
pH _________________(1)
(ii) The answer you gave in part (b)(i) may not be the exact pH at which pepsin works best.
What could the students do to find a more accurate value for this pH?
______________________________________________________________
____________________________________________________________________________________________________________________________
______________________________________________________________(2)
(iii) There was no change in the length of the egg white from pH 5 to pH 7.
Explain why.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(c) Pepsin is made by the stomach.
Name the acid made by the stomach which allows pepsin to work well.
___________________________________________________________________(1)
(Total 8 marks)
Q6.Scientists investigated a food chain in a wheat field immediately after the wheat had been harvested.
Red kites are birds of prey.
(a) The food chain for the wheat field is:
Wheat grains Field mice Red kites
What is the source of energy for the food chain?
___________________________________________________________________(1)
(b) The table shows the data the scientists collected.
OrganismEstimated
numberin the field
Biomass of oneorganism in kg
Total biomass for
field in kg
Fallen wheat grains 40 000 0.0006 24.0
Red kites 2 1.0 ..........
Field mice 200 0.04 ..........
(i) Complete the table by calculating the total biomass of red kites and of field mice.
Write your answers in the table.(2)
(ii) Use data from your completed table to draw a pyramid of biomass for the food chain shown in the table.
You should label each layer of your pyramid.
Total biomass for field in kg(3)
(c) The total biomass of the red kites is less than the total biomass of the field mice.
Give two reasons why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(d) The scientists could not find the exact number of organisms in the wheat field.
Suggest two reasons why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(Total 10 marks)
Q7.(a) Complete the equation for photosynthesis. Draw a ring around each correct answer.
hydrogen alcohol
Carbon dioxide + nitrogen light energy glucose + oxygen
water methane
(2)
Some students investigated the effect of light intensity on the rate of photosynthesis in pondweed.
The diagram shows the apparatus the students used.
The closer the lamp is to the pondweed, the more light the pondweed receives.
The students placed the lamp at different distances, d, from the pondweed.
They counted the number of bubbles of gas released from the pondweed in 1 minute for each distance.
(b) A thermometer was placed in the glass beaker.
Why was it important to use a thermometer in this investigation?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
(c) The students counted the bubbles four times at each distance and calculated the correct mean value of their results.
The table shows the students’ results.
Distanced in cm
Number of bubbles per minute
1 2 3 4 Mean
10 52 52 54 54 53
20 49 51 48 52 50
30 32 30 27 31 30
40 30 10 9 11
(i) Calculate the mean number of bubbles released per minute when the lamp was 40 cm from the pondweed.
______________________________________________________________
______________________________________________________________
Mean number of bubbles at 40 cm = ______________________(2)
(ii) On the graph paper below, draw a graph to show the students’ results:
• add a label to the vertical axis• plot the mean values of the number of bubbles• draw a line of best fit.
Distance d in cm(4)
(iii) One student concluded that the rate of photosynthesis was inversely proportional to the distance of the lamp from the plant.
Does the data support this conclusion?
Explain your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(d) Light intensity, temperature and concentration of carbon dioxide are factors that affect the rate of photosynthesis.
Scientists investigated the effects of these three factors on the rate of photosynthesis in tomato plants growing in a greenhouse.
The graph below shows the scientists’ results.
Light intensity in lux
A farmer in the UK wants to grow tomatoes commercially in a greenhouse.
The farmer read about the scientists’ investigation.
During the growing season for tomatoes in the UK, natural daylight has an intensity higher than 30 000 lux.
The farmer therefore decided to use the following conditions in his greenhouse during the day:
• 20°C
• 0.1% CO2
• no extra lighting.
Suggest why the farmer decided to use these conditions for growing the tomatoes.
You should use information from the scientists’ graph in your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
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___________________________________________________________________(4)
(Total 17 marks)
Q8.The lugworm lives in a U-shaped burrow in the sand on the seashore.
The diagram below shows a lugworm in its burrow.
(a) Some scientists investigated the effect of different salt concentrations on lugworms.
The scientists:
• collected 50 lugworms from the seashore
• separated them into five groups of 10 lugworms
• weighed each group of 10 lugworms
• placed each group into a different concentration of salt solution and left them for 8 hours
• took each lugworm out of the solution and placed it on blotting paper for 30 seconds
• re-weighed each group of 10 lugworms.
(i) Why did the scientists use groups of 10 lugworms and not just 1 lugworm at each concentration?
______________________________________________________________
______________________________________________________________(1)
(ii) Suggest why the scientists placed each lugworm on blotting paper for 30 seconds before they reweighed the groups of lugworms.
______________________________________________________________
______________________________________________________________(1)
(iii) How might the method of blotting have caused errors in the results?
______________________________________________________________
______________________________________________________________(1)
(iv) Suggest one improvement the scientists could make to their investigation.
______________________________________________________________(1)
(b) The table below shows the scientists’ results.
Concentration of salt in arbitrary units
Mass of 10 lugworms at start in
grams
Mass of 10 lugworms
after 8 hours in grams
Change in mass in grams
Percentage (%) change in mass
1.0 41.2 61.8 +20.6 +50
2.0 37.5 45.0 +7.5
3.0 55.0 56.1 +1.1 +2
4.0 46.2 22.2 -24.0 -52
5.0 45.3 22.6 -22.7 -50
(i) The scientists calculated the percentage change in mass at each salt concentration.
Why is the percentage change in mass more useful than just the change in mass in grams?
Use information from the table in your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) Calculate the percentage change in mass for the 10 lugworms in the salt solution with a concentration of 2.0 arbitrary units.
______________________________________________________________
______________________________________________________________
Percentage change in mass = ______________________ %(2)
(c) (i) On the graph paper below, draw a graph to show the scientists’ results:
• plot the percentage change in mass
• label the horizontal axis
• draw a line of best fit.
(4)
(ii) The scientists thought one of their results was anomalous.
Draw a ring around the anomalous result on your graph.(1)
(iii) Suggest what might have happened to cause this anomalous result.
______________________________________________________________
______________________________________________________________(1)
(d) (i) What do you think is the concentration of salts in the lugworm’s natural environment?
Use information from your graph to give the reason for your answer.
Concentration = ______________________ %
Reason _______________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) The mass of the lugworms decreased in the salt solution with a concentration of 5.0 arbitrary units.
Explain what caused this.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(3)
(Total 19 marks)
Q9.A project called Garden Bird Watch counts the UK populations of common birds. 16 000 people count the number of birds in their gardens every week of the year.
The results are analysed by researchers and written up in important scientific magazines.
(a) Suggest one advantage of this method of collecting data.
___________________________________________________________________
___________________________________________________________________
The table below shows the percentage (%) of gardens visited by different bird species in 1995 and in 2011.
Bird species% of gardens
visited in 1995
% of gardens visited in
2011
Goldfinch 12 58
Greenfinch 71 54
House sparrow 84 64
Starling 71 42
Woodpigeon 48 80
(1)
(b) (i) Complete the bar chart below, by plotting the data from the table above for 2011.
Some have been done for you.
Bird species(2)
(ii) In this survey, the results from 16 000 gardens were sent in.
How many gardens were visited by woodpigeons in 2011?
______________________________________________________________(2)
(iii) Which bird species has increased the most from 1995 to 2011?
______________________________________________________________(1)
(c) The change in the number of woodpigeons may be partly because they have spread to towns and cities.Suggest why this increase in woodpigeons in towns and cities might have occurred.
___________________________________________________________________
___________________________________________________________________(1)
(Total 7 marks)
Q10.Lichens can be used as air pollution indicators.
The graph below shows the number of lichen species found growing on walls and trees at increasing distances from a city centre.
Distance from city centre in km
(a) (i) How many species of lichen are found on walls 2 km from the city centre?
______________________________________________________________(1)
(ii) Describe the patterns in the data.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(3)
(b) The table below shows the concentration of sulfur dioxide (SO2) in the air at different distances from the same city centre.
Distance from city centre in km
SO2 concentration in g per m3
0 200
3 160
8 110
13 85
18 65
Suggest how the data in the table could explain the patterns in the graph above.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(c) Nitrogen oxides are also air pollutants.
The main source of nitrogen oxide pollution comes from road vehicles.
Different lichen species vary in their tolerance of the levels of nitrogen oxides in the air.
Some lichens can only grow in very clean air where there are low levels of nitrogen oxides. They are nitrogen-sensitive.
Some lichens grow very well in high levels of nitrogen oxides. They are nitrogen-loving.
The table below shows one lichen species which is nitrogen-sensitive and one lichen species which is nitrogen-loving.
Nitrogen-sensitive Nitrogen-loving
Usnea Xanthoria
Usnea © epantha/iStock/Thinkstock;Xanthoria By Zakwitnij!pl Ejdzej + Iric (CC BY-SA.2.0) via wikicommons
(i) Describe how you would investigate the distribution of the two lichens at different distances into a wood from a main road.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(3)
(ii) Predict the results from the experiment you described in your answer to part (c)(i). Explain why you made this prediction.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
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______________________________________________________________(3)
(Total 12 marks)
Mark schemes
Q1.(a) (i) 5.0
1
(5 × 0.8) or 4allow ecf from distance
1
0.4allow ecf from 10-min volume
1
(ii) increased (rate of uptake)1
more transpiration / evaporation1
(b) correct scalesallow reversed axes
1
correctly labelled axes with units1
correct pointsone plot error = max 1 mark
2
curved line of best fitallow correct straight line
1
(c) leaves wilt1
because plants lose too much water (by evaporation)1
through the stomataorbecause cells become plamolysedorstomata closecontrolled by guard cellsto prevent wilting
1[13]
Q2.(a) 6H2O
in the correct order1
C6H12O6
1
(b) (i) controldo not accept ‘control variable’allow:to show the effect of the organismsorto allow comparisonorto show the indicator doesn’t change on its own
1
(ii) snail respires1
releases CO2
1
(iii) turns yellow1
plant can't photosynthesise so CO2 not used up1
but the snail (and plant) still respires so CO2 produced1
[8]
Q3.(a) estimate / count number of squares covered
do not allow number of squares containing algae1
divide by total number of squares and multiply by 100 / multiply by 41
(b) (i) any two from:
• more / most in North east facing• followed by the North facing• the South facing had no green alga / least
2
(ii) 40 (%)1
two directions had this value (rest of directions had only one)accept this is the most common percentage / value2nd mark only if 40(%)
1
(iii) any three from:• light / sunlight
ignore Sun / carbon dioxide• temperature
do not accept oxygen• availability of water / humidity• availability of nutrients• wind• pollution qualified eg SO2, acid rain, soot
• grazing by animals eg slugs• competition with other species• pH
3
(iv) eg (for light)allow overlap between factors
light intensity least on north / north east facing parts of tree (1)1
green algae adapted for photosynthesis in low light intensities (1)allow, since less light from Sun, cooler so less evaporation
1
negative effect of high light intensity on green algal chlorophyll / photosynthetic pigments (1)
allow green algae unable to withstand desiccation1
or (for temperature)
temperature highest on south (and west) facing parts of tree
(causing) more water to evaporate from this side of tree
green algae unable to withstand desiccation
or (for moisture / rainfall)
rainfall highest on north / north east facing parts of tree (1)
(giving) more moisture on this part of tree (1)
green algae less likely to desiccate (1)
or (for wind)
wind speed / duration greatest on south (and west) facing parts of tree (1)
(causing) more water to evaporate from this side of tree (1)allow wind carries pollutantsallow pollutants toxic to algae
green algae unable to withstand desiccation (1)
or (from pollution)
from south / south west (1)
wind carries pollutants (1)
pollutants toxic to / kill algae (1)
(c) (i) as the concentration of ammonia increases so does the % abundance of nitrophyte lichens
allow positive correlation / proportionalallow directly proportional
1
scattered results / wide spreadallow use of approximate numbers to demonstrate scattering
or
for any value of one parameter there is a wide range of the otherallow not a strong relationship / correlation
1
(ii) not very useful / unreliableaccept only gives a rough idea / only a general indication
1
for any value of one parameter there is a wide range of the otherallow correlation rather than direct relationship
or
scattered results1
[16]
Q4.(a) (i) decrease
1
rate of decrease slows1
(ii) any one from:• more use of disinfectant
allow any reasonable increase in hygiene or sterilisation precautions
• more use of hand washing• more careful / more often cleaning of patient facilities• raised awareness / education about hygiene
1
Explanation:stops / reduces the bacteria being transferred / spreading
1
(iii) 800 – 500 / 800 × 100 =1
37.5 (%)correct answer with or without working gains 2 marks
1
(iv) any one from:
• numbers quite low now so hard to reduce further• was a big campaign / much publicity (in 2009) so more people already
doing it• hygiene / cleaning now good so hard to improve• hospitals short of money so less staff to clean
1
(b) mutation occurred giving resistance (to methicillin)
do not accept overuse caused mutation1
resistant bacteria not able to be treated / not killed1
these bacteria multiplied / reproduced / spread quickly1
[10]
Q5.(a) (i) amino acid(s)
accept peptide(s)do not allow polypeptide(s)
1
(ii) protease1
(b) (i) 21
(ii) repeatdo not allow other enzyme / substrate
1
using smaller pH intervals between pH1 and pH3allow smaller intervals on both sides of / around pH2allow smaller intervals on both sides of / around answer to (b)(i)
1
(iii) enzyme / pepsin denatured / shape changeddo not allow enzyme killedallow enzyme ‘destroyed’
1
enzyme / pepsin no longer fits (substrate)allow enzyme / pepsin does not work
1
(c) hydrochloric (acid)allow phonetic spellingaccept HClallow HCLignore hcldo not allow incorrect formula –e.g. H2Cl / HCl2
1[8]
Q6.(a) Sun / sunlight / light
accept radiation from the Sun / solar energy1
(b) (i) 2 (.0)
1
8 (.0)1
(ii) 3 layers of decreasing size as they go up1
labelled wheat grains, field mice, red kites in correct order of food chain1
sizes correct (showing half on each side)allow ecf from (b)(i)error ± half square
1
(c) any two from:
• not all the field mice are eaten• not all parts of eaten mice are absorbed / some passed as faeces (of red kite)• due to respiration (of red kites) / production of CO2
allow reference to uric acid / urea / urine (of red kite)reference to waste / excretion alone gains 1 mark
2
(d) any two from:
• cannot find all wheat grains / too many to count• field mice hiding / in hedgerows
allow ref to hibernation / nests / burrows• red kites / mice come and go all the time
allow count an organism more than once2
[10]
Q7.(a) LHS = water
1
RHS = glucose1
(b) any three from:
• (measure) temperatureignore reference to fair test
• to check that the temperature isn’t changing• rate of reaction changes with temperature• temperature is a variable that needs to be controlled
allow lamp gives out heat3
(c) (i) 10correct answer = 2 marks
allow 1 mark for: allow 1 mark for correct calculation without removal of
anomalous result ie 152
(ii) graph:allow ecf from (c)(i)
label on y-axis as ‘number of bubbles per minute’1
three points correct = 1 markallow ± 1 mm
four points correct = 2 marks2
line of best fit = smooth curve1
(iii) as distance increases, rate decreases – proallow yes between 20 – 40
1
but should be a straight line / but line curves – con / not quite proallow not between 10 – 20if line of best fit is straight line, allow idea of poor fit
1
(d) any four from:
• make more profit / cost effective• raising temp. to 25 °C makes very little difference at 0.03% CO2
• (at 20 °C) with CO2 at 0.1%, raises rate• (at 20 °C with CO2 at 0.1%) → >3x rate / rises from 5 to 17• although 25 °C → higher rate, cost of heating not economical• extra light does not increase rate / already max. rate with daylight
accept ref to profits c.f. costs must be favourable4
[17]
Q8.(a) (i) variation in masses / more representative / more typical / more reliable /
average / mean / reference to anomalies
or
one worm to light to measure changedo not allow more accurate / more preciseignore fair test / valid / repeatable / reproducible
1
(ii) remove solution / liquid (on outside of worm)allow ‘water’
1
(iii) variable amounts removed from each wormignore reference to length of timing
1
(iv) equal sizes of worm / more worms (in each group) / wash off all the sand / repeats / use more accurate balance / use smaller concentration intervals
allow reference to improve blotting technique eg blot before / blot more thoroughly
1
(b) (i) different (starting) masses / sizes / weights (at different concentrations)1
allows comparisons / shows pattern / shows trend1
(ii) (+)20correct answer = 2 marks, with or without workingor
for 1 mark
2
(c) (i) graph:
points correctallow ± 1 mm–1 mark per errorallow ecf from part b(ii)
2
label on x-axis including units – ie Concentration of salt in arbitrary units1
line of best fit = smooth curve / ruled straight lineanomaly (4.0, –52) either plotted and ignored re. lineor not plotteddo not allow point to pointallow best fit for ecf from 2bii
1
(ii) on graph:
ring drawn around point at (4.0, –52)allow (5.0, –50) if cand. line indicates this
1
(iii) sensible suggestion – eg used wrong solution / used 5.0% instead of 4.0% / different length of time in solutions / ref to error in blotting / balance not zeroed / error in weighing
allow some lugworms diedallow error in calculation
1
(d) (i) 2.9 to 3.0 / correct for candidate’s graph ± 0.11
value of no change in mass / worms in equilibrium with soln / describedallow small(est) mass change
1
(ii) water loss1
by osmosis / diffusion1
from dilute region in the worm to more concentrated solution outsideallow correct description in terms of high to low water concentration / high to low water potentialsalt solution is hypertonicconcentration unqualified = salt concentration
1[19]
Q9.(a) any one from:
• get lots of dataaccept more reliable / reproducibledo not accept more accurate
• cheap / free• unlikely to be biased• can cover a wide area at the same time / takes less time• see seasonal variations
1
(b) (i) correct bar heights1 mark for each correct barignore width of bars
2
(ii) 12 800(16000 / 100)x80 on its own for 1 mark
2
(iii) goldfinch1
(c) any one from:
• more food availableaccept fewer predators
• people feed themaccept less habitat / food in countryside
• more rubbish / waste to eat1
[7]
Q10.(a) (i) 10
1
(ii) any three from:
• both increase with distance• more spp on walls than on trees
• no lichen spp on trees for first 1 km from city• more steady / less erratic increase on trees than walls (or
converse)• rate of increase increases with distance
3
(b) SO2 decreases with distance from centreaccept converseIgnore pollution
1
high SO2 reduces survival or kills lichenaccept converse
1
(c) (i) any three from:
• (line) transect• quadrat / reference to specific area• count number of lichens or coverage on trees• at regular intervals / set distances
3
(ii) (more) Xanthoria nearest roadallow ‘nitrogen-loving’ for Xanthoria
1
(more) Usnea further from the roadallow ‘nitrogen-sensitive’ for Usnea
1
because most nitrogen oxide from vehicles (near road)
or
because nitrogen oxide levels will be falling / less further away (from road)
accept converse1
[12]
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