GCSE Combined Science Biology
Practice Questions
Paper 1
Grade 7-9
Page 1 of 46
Q1.
The photograph below shows part of one liver cell.
The photograph was taken with an electron microscope.
(a)
Name structure X.
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(1)
(b)
Describe the function of mitochondria.
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(3)
(c)
Protein synthesis occurs at ribosomes.
Describe the structure of a protein molecule.
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(2)
Page 2 of 46
(d)
The storage substance in liver cells is a carbohydrate.
Name the carbohydrate storage substance found in liver cells.
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(1)
Electron microscopes have higher resolving power than light microscopes.
(e)
What is the resolving power of a microscope?
Tick (✓) one box.
How far the focusing knob has to be adjusted to form
a clear image
The number of times larger than real life the image
appears
The shortest distance between two points that can be
seen as separate points
(1)
(f)
An electron microscope has a magnification of × 650 000
The length of a cell structure in an image from the electron microscope was 27 mm
Calculate the real length of this cell structure in mm
Give your answer to 2 significant figures.
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Real length of cell structure (2 significant figures) = _______________ mm
(4)
(Total 12 marks)
Q2.
Figure 1 shows a root hair viewed using a microscope.
Figure 1
Page 3 of 46
(a)
The root hair was viewed at a magnification of ×50
The image length of the root hair X–Y is 43 mm
Calculate the real length of the root hair in micrometres (µm).
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Real length = ___________________________ µm
(4)
(b)
A microscope has a ×5 eyepiece lens.
Describe how to use this microscope to observe a prepared slide of root hair cells at a magnification of ×50
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(4)
Root hair cells absorb water and mineral ions from the soil.
A scientist investigated the rate of nitrate ion uptake by two seedlings.
Figure 2 shows how the investigation was set up.
Figure 2
Page 4 of 46
The scientist determined the mass of nitrate ions absorbed by each seedling every 30 minutes for 4 hours.
The table shows the results.
Time in
hours
(c)
Total mass of nitrate ions absorbed by seedling in arbitrary
units
With oxygen added
With no oxygen added
0
0
0
0.5
100
60
1.0
145
95
1.5
170
105
2.0
195
115
2.5
215
120
3.0
235
125
3.5
250
130
4.0
265
130
Describe the changes in the rate of absorption of nitrate ions for the seedling with no oxygen added.
Use information from the table.
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(3)
(d)
Explain what the results in the table above show about how nitrate ions are absorbed.
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Page 5 of 46
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(4)
(e)
Nitrate ions are essential for plants to grow.
Describe how nitrate ions are used in a plant to help the plant grow.
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(3)
(Total 18 marks)
Q4.
A student investigated the effect of different concentrations of sugar solution on pieces of carrot.
This is the method used.
1.
2.
3.
4.
5.
6.
7.
Weigh five pieces of carrot.
Place each piece into a different tube.
Into each tube add 20 cm3 of water or one of the sugar solutions as shown in Figure 1
Leave the apparatus for 2 hours.
Remove the carrot and dry each piece on paper towel.
Reweigh each piece.
Calculate the percentage (%) change in mass of each piece.
Figure 1 shows how the investigation was set up.
Figure 1
The table below shows the results.
Concentration of sugar
solution in mol/dm3
Percentage (%) change in
mass
0.0
+24
0.2
+12
Page 6 of 46
(a)
0.4
+1
0.6
−8
0.8
−15
Suggest why the student calculated the percentage (%) change in mass of each piece of carrot.
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(1)
(b)
Complete Figure 2 using the results in the table above
•
•
•
Choose a suitable scale and label for the y-axis.
Plot the results.
Draw a line of best fit.
Figure 2
(4)
Page 7 of 46
(c)
Estimate the concentration of sugar solution inside the carrot cells.
Use your completed graph on Figure 2
Concentration = _______________________ mol/dm3
(1)
(d)
Explain why the mass of the carrot in the 0.6 mol/dm3 sugar solution changed.
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(4)
(e)
The student repeated the investigation using boiled pieces of carrot.
The pieces of carrot did not change in mass.
Suggest why.
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(1)
(Total 11 marks)
Q5.
Substances are transported across cell membranes by different processes.
Figure 1 represents a section of cell membrane in a plant root.
Figure 1
Page 8 of 46
(a)
Substance B moves into the root cell.
Suggest what substance B is.
Explain your answer.
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(3)
Students wanted to determine the concentration of sugar solution in dandelion cells.
This is the method used.
1. Cut a 40 mm length of dandelion stem into five identical strips.
2. Draw the appearance of a strip.
3. Place each strip into a different concentration of sugar solution.
4. After 1 hour, draw the appearance of each strip.
Figure 2 shows how the dandelion stem was cut.
Figure 2
The cells on the outer edge of the dandelion strip have a waxy waterproof layer.
The table shows the students’ drawings of the strips of dandelion stem.
Page 9 of 46
(b)
Explain the result for the 0.2 mol/dm3 sugar solution.
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(4)
(c)
Suggest the concentration of sugar solution in the dandelion cells.
Use the table above.
Concentration = ___________________________ mol/dm3
(1)
(d)
Explain your answer to part (c).
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Page 10 of 46
(2)
(e)
The results shown in the table above are qualitative.
Qualitative results depend on a person’s judgement so may not be accurate.
The students wanted to determine the concentration of sugar solution in dandelion cells.
Describe how the method could be improved to obtain an accurate, quantitative result.
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(2)
(Total 12 marks)
Q8.
Amylase is an enzyme that digests starch.
(a)
Which organs in the human digestive system produce amylase?
Tick (✓) one box.
Liver, small intestine and large intestine
Salivary glands, stomach and liver
Salivary glands, pancreas and small intestine
Stomach, pancreas and large intestine
(1)
A student investigated the effect of pH on the activity of amylase.
This is the method used.
1.
Prepare amylase solution at pH 5
2.
Mix the amylase solution with starch in a boiling tube.
3.
Remove a drop of the amylase-starch mixture every 30 seconds and test it for the presence of starch.
4.
Record the time when all the starch has been digested.
5.
Repeat steps 1 to 4 using amylase solution prepared at pH 6, then at pH 7 and then at pH 8
(b)
What was the independent variable in this investigation?
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(1)
Page 11 of 46
(c)
Describe how the student would know when all the starch had been digested.
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(1)
(d)
Figure 1 shows the student’s results.
Figure 1
What was the optimum pH for the amylase?
Use Figure 1.
Optimum pH = _______________
(1)
A scientist did a different investigation.
This is the method used.
1.
Prepare amylase solution at the optimum pH.
2.
Mix the amylase solution with starch in a boiling tube.
3.
Measure the concentration of sugar every 10 seconds for 2 minutes.
Figure 2 shows the scientist’s results.
Figure 2
Page 12 of 46
(e)
How much time did it take for the amylase to digest all the starch?
Use Figure 2.
Time to digest all the starch = _______________ seconds
(1)
(f)
Determine the rate of sugar production per minute at 40 seconds.
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Rate = _______________ arbitrary units per minute
(4)
(g)
Explain how the structure of enzyme molecules is related to the effect of pH on the activity of amylase.
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Page 13 of 46
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(6)
(Total 15 marks)
Q10.
Photosynthesis is an important chemical reaction in plants.
(a)
Why is light needed for photosynthesis?
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(1)
(b)
What is the equation for photosynthesis?
Tick (✓) one box.
C6H12O6 + CO2 → 6 O2 + 6 H2O
CO2 + H2O → CH2O + O2
6 CO2 + 6 H2O → C6H12O6 + 6 O2
6 O2 + 6 H2O → C6H12O6 + 6 CO2
(1)
(c)
A student investigated the effect of different colours of light on the rate of photosynthesis at room temperature.
The student used pondweed in water.
A piece of pondweed was placed in red light, then in blue light and then in green light.
Each colour of light was the same intensity.
Describe how the student should make accurate measurements to obtain valid results for the rate of photosynthesis.
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Page 14 of 46
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(4)
A scientist investigated the effect of different wavelengths of light on the rate of photosynthesis.
The wavelength of light determines the colour of the light.
Figure 1 shows the student’s results.
Figure 2 shows the scientist’s results.
Figure 1
Figure 2
Page 15 of 46
(d)
Why are the results for the two investigations presented differently?
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(2)
(e)
Suggest the range in wavelength of green light.
Use Figure 1 and Figure 2.
Range in wavelength of green light = from _______ nm to _______ nm
(1)
(Total 9 marks)
Q11.
This question is about photosynthesis.
(a)
What is the correct balanced equation for photosynthesis?
Tick one box.
C6H12O6 + 6O2 ⟶ 6CO2 + 6H2O
O2 + H2O ⟶ C6H12O6 + CO2
Page 16 of 46
6CO2 + 6H2O ⟶ C6H12O6 + 6O2
6O2 + 6CO2 ⟶ 6H2O + C6H12O6
(1)
(b)
What type of reaction is photosynthesis?
Tick one box.
Aerobic
Endothermic
Exothermic
Oxidation
(1)
A student investigated the effect of light intensity on the rate of photosynthesis.
The diagram below shows the apparatus used.
Sodium hydrogencarbonate solution releases carbon dioxide gas for the pondweed.
This is the method used.
1.
2.
3.
Place the pondweed at 5 cm from the light source.
Measure the rate of photosynthesis by counting the number of bubbles produced in 1 minute.
Repeat with the pondweed at 10 cm and at 20 cm from the light source.
(c)
Counting the number of bubbles produced in 1 minute is not an accurate way to measure the rate of photosynthesis.
Suggest two ways the method could be improved to measure the rate of photosynthesis more accurately.
1. _________________________________________________________________
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Page 17 of 46
2. _________________________________________________________________
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(2)
(d)
The LED light source does not get hot.
Explain why it is important that the pondweed remains at a constant temperature.
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(2)
(e)
Light intensity can be calculated using the inverse square law:
Where I is light intensity and d is the distance of the pondweed from the light source.
The student placed the pondweed at 5, 10 and 20 cm from the light source.
Explain how light intensity changes as the distance of the pondweed from the light source is doubled.
You must include calculations in your answer.
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(3)
(f)
The student’s results are shown in the table below
Distance of the pondweed from
the light source in cm
Number of bubbles produced in 1
minute
5
129
10
31
20
8
Predict how many bubbles of gas would be produced in 1 minute if the pondweed was placed 40 cm from the light
source.
Give a reason for your prediction.
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Page 18 of 46
(2)
(g)
Describe how the student could change the method to investigate the effect of carbon dioxide concentration on the
rate of photosynthesis.
You should include:
•
•
how to change the independent variable
two control variables.
Use the diagram above to help you answer this question.
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(3)
(Total 14 marks)
Q15.
The photograph below shows a wound dressing put over a cut on a person’s hand.
‘Smart’ wound dressings contain tiny electronics and sensors.
Smart dressings constantly monitor the wound to show if the wound is infected.
The information from the smart dressing can be sent wirelessly to the mobile phones of the patient and their doctor.
Smart dressings can release antibiotics if needed.
Evaluate the use of smart dressings compared with the use of the wound dressing shown in the photograph above.
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Page 19 of 46
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(Total 6 marks)
Q16.
Being overweight can affect the health and life expectancy of a person.
(a)
Give one disease related to being overweight.
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(1)
(b)
Body mass index (BMI) helps to show if a person has a healthy body mass for their height.
BMI is calculated using the equation:
A woman has a BMI of 27 and a body mass of 68.1 kg
Calculate the woman’s height in metres.
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Height = _______________ m
(3)
(c)
The graph below shows a height-body mass chart for adults.
Page 20 of 46
Which weight category describes the woman in part (b)?
Tick (✓) one box.
Underweight
Healthy weight
Overweight
Obese
(1)
(d)
People are encouraged to control their body mass with diet and exercise.
Describe how the balance between the mass of food eaten and the amount of exercise a person does controls body
mass.
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Page 21 of 46
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(3)
(e)
During long periods of vigorous exercise the body respires anaerobically.
Explain the changes that happen in the body during and after vigorous exercise.
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(6)
(Total 14 marks)
Q17.
On aeroplanes, pathogens can easily spread from one person to another person.
(a)
Suggest one way pathogens can spread from one person to another person on an aeroplane.
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(1)
The manufacturer of a nose spray claims that:
‘The nose spray defends against diseases such as the common cold.’
The nose spray puts a thin layer of gel in the airways between the nose and the lungs.
(b)
Describe how the nose spray and the body’s natural defences in the airways work in similar ways to defend against
pathogens.
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(3)
(c)
The nose spray was tested as a new medical drug.
The manufacturer of the nose spray claims:
Page 22 of 46
‘The nose spray can decrease the number of days that
a person has symptoms of the common cold.’
Suggest one reason why this claim is difficult to test.
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(1)
(d)
The nose spray contains a mixture of ingredients.
Suggest two reasons why the nose spray is a mixture of ingredients.
1 _________________________________________________________________
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2 _________________________________________________________________
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(2)
(e)
Late-stage HIV (AIDS) affects the immune system.
A person with AIDS is more likely to suffer from another infectious disease.
Give one other example of how having one disease can affect the development of a different disease.
Do not refer to HIV or AIDS.
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(1)
(Total 8 marks)
Q18.
Adult stem cells are found in human bone marrow.
Bone marrow stem cells can differentiate into many types of blood components.
The figure below shows the components the bone marrow stem cells can differentiate into.
Page 23 of 46
(a)
Name the component of the blood labelled A.
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(1)
(b)
Damage to the bone marrow will lead to a reduction in the number of blood components produced in a person.
Describe the effect a reduction of component A will have on the person.
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(1)
(c)
A person has 5.1 × 109 red blood cells per cm3 of blood.
The person has 4.25 dm3 of blood in their body.
A total of 2.0 × 1011 of the red blood cells are replaced each day.
Calculate the percentage of red blood cells that are replaced each day.
1 dm3 = 1000 cm3
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Page 24 of 46
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Percentage of red blood cells replaced each day = ____________________ %
(4)
(d)
Explain why red blood cells cannot divide by mitosis.
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(2)
(e)
The different components of the blood can be used to treat different medical conditions.
The table below gives information about:
•
blood from blood donation by volunteers
•
the production of red blood cells from stem cells in laboratories.
Blood from blood donation
It can take 10 minutes to collect blood from a vein
in the arm.
Production of red blood cells from stem cells
Red blood cells can be produced when needed in
small quantities.
A person can donate blood every 12 weeks.
It takes 28 days to produce red blood cells.
Blood can be stored for 35 days.
Blood can be separated into different blood
components and plasma.
A patient’s own stem cells can be used to make
red blood cells.
Evaluate the use of blood donation to provide blood components compared with using stem cells to provide blood
components.
Use information from the table above and your own knowledge.
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(6)
(Total 14 marks)
Page 25 of 46
Q19.
The figure below shows the human heart.
(a)
Which blood vessel transports blood with the highest oxygen concentration into the heart?
Tick (✓) one box.
A
B
C
D
(1)
(b)
Blood pressure is a measure of the force of the blood against the walls of the blood vessels.
Which blood vessel transports blood at the highest pressure?
Tick (✓) one box.
A
B
C
D
(1)
(c)
What is the correct order for blood flowing through the heart to the lungs?
Tick (✓) one box.
left atrium → left ventricle → pulmonary artery
left atrium → left ventricle → pulmonary vein
right atrium → right ventricle → pulmonary artery
right atrium → right ventricle → pulmonary vein
(1)
Every year thousands of people in the UK have heart attacks.
Page 26 of 46
A heart attack is caused when the heart muscle cells do not get enough oxygen, causing the cells to die.
(d)
Statins and stents are two treatments used to reduce the risk of someone having a heart attack.
Evaluate the use of statins compared with the use of a stent to reduce the risk of a heart attack.
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(6)
(e)
Many people who survive a heart attack get out of breath easily when they exercise gently.
Explain why heart attack survivors get out of breath easily.
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(4)
Scientists have developed patches of beating heart cells to repair damaged heart tissue.
The patches are placed onto areas of the heart where cells have died. New cells grow to replace the dead cells.
The patches are made using a person’s own cells that are converted into stem cells.
(f)
Explain why stem cells are used to make the patches.
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(2)
Page 27 of 46
(g)
The scientists could have used human embryonic stem cells to make the patches.
Give two advantages of using stem cells made from the person’s own cells, rather than using embryonic stem cells.
1
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2
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(2)
(Total 17 marks)
Q20.
This question is about photosynthesis and food production.
(a)
How can oxygen production be used to show the rate of photosynthesis?
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(1)
Scientists investigated factors affecting the rate of photosynthesis in tomato plants.
The tomato plants were growing in a commercial greenhouse in the UK during winter.
The graph below shows the results.
The percentage of carbon dioxide in the Earth’s atmosphere is 0.04%
(b)
Name the factor that is limiting the rate of photosynthesis at point X.
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(1)
Farmers growing tomatoes commercially try to control the rate of photosynthesis and make maximum profit.
Page 28 of 46
A farmer can control the temperature and carbon dioxide concentration in a greenhouse.
(c)
What is the minimum light intensity a farmer should use to get the maximum rate of photosynthesis shown in above
graph?
Light intensity = _______________ lux
(1)
(d)
The light intensity you gave in part (c) may not give the farmer maximum profit.
Explain why.
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(3)
(e)
Explain the results when the light intensity was 0 lux.
Use the diagram above.
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(4)
(Total 10 marks)
Q21.
The figure below shows four different types of cell.
(a)
Which cell is a plant cell?
Give one reason for your answer.
Cell _________
Page 29 of 46
Reason ____________________________________________________________
(2)
(b)
Which cell is an animal cell?
Give one reason for your answer.
Cell _________
Reason ____________________________________________________________
(2)
(c)
Which cell is a prokaryotic cell?
Give one reason for your answer.
Cell _________
Reason ____________________________________________________________
(2)
(d)
A scientist observed a cell using an electron microscope.
The size of the image was 25 mm.
The magnification was × 100 000
Calculate the real size of the cell.
Use the equation:
Give your answer in micrometres.
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Real size = __________________ micrometres
(3)
(Total 9 marks)
Q22.
An understanding of relative size is essential in science.
(a)
Draw one line from each structure to the approximate radius of that structure.
Structure
Approximate radius
1 × 10−14 m
a bacterial cell
5 × 10−10 m
a large molecule
1 × 10−10 m
an animal cell
1 × 10−6 m
an atom
2 × 10−5 m
Page 30 of 46
3 × 10−9 m
(4)
The diagram below shows two model cells.
(b)
Describe how the surface area to volume ratio changes as the length of the side of the model cell increases.
You should include calculations in your answer.
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(3)
(c)
Explain why a bacterium can rely on diffusion for gas exchange, but animals need a transport system.
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(3)
(d)
Some sugar molecules are absorbed from the small intestine into the blood by active transport.
Explain why the rate of absorption of these sugar molecules can depend on the concentration of oxygen in the cells
lining the small intestine.
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(3)
(Total 13 marks)
Page 31 of 46
Mark schemes
Q1.
(a)
nucleus
1
(b)
(where aerobic) respiration (occurs)
1
(which) releases energy
do not accept makes / produces / creates energy
1
(energy released) from glucose (using oxygen)
or
(energy released) for cell reactions / movement / muscle contraction
(energy released) for metabolic reactions
1
(c)
amino acids
1
(many) joined / linked / bonded together
allow giant (covalent) structure, macromolecule, long chain,
polymer, polypeptide
1
(d)
glycogen
allow phonetic spelling do not accept glucagon / glucose / glycerol
1
(e)
the shortest distance between two points that can be seen as separate points
1
(f)
650 000 =
1
real length =
1
0.000041538 (mm)
allow more or fewer significant figures
1
0.000042 (mm)
allow 4.2 × 10–5 (mm)
1
[12]
Q2.
(a)
1
(size of real object =)
1
(size of real object =) 0.86 (mm)
1
(size of real object =) 860 (µm)
an answer of 860 (µm) scores 4 marks
allow correct conversion of their calculated value
Page 32 of 46
if no other marks awarded allow 1 mark for
1
(b)
Level 2: Scientifically relevant facts, events or processes are identified and given in detail to form an accurate
account.
3−4
Level 1: Facts, events or processes are identified and simply stated but their relevance is not clear.
1−2
No relevant content
0
Indicative content
•
•
•
•
•
•
•
•
•
•
•
place slide on stage
use lowest power / ×4 objective lens (initially)
adjust mirror or switch light on so light passes through slide
move stage as close to lens as possible
slide must not touch lens
turn focussing knob so slide moves away from lens
turn focussing knob until image comes into focus
use fine focus to get clear image
change objective lens to ×10
×5 eyepiece and ×10 objective lenses (gives total magnification of ×50)
refocus slide using focussing knob
For Level 2 reference to how to focus the slide / cells and achieve magnification of ×50 is required
(c)
any three from:
•
(rate) fastest in the first 0.5 hours
allow fastest rate is 120 units per hour (at start)
•
(rate gradually) decreases after first 0.5 hours
•
allow mean rate over 3.5 hours is 37.14 units per hour
or
(rate gradually) decreases throughout the investigation
•
•
rate is constant between 1.0 and 2.0 hours
or
rate is constant between 2.0 and 3.5 hours
•
(rate) becomes zero between 3.0 and 3.5 hours
allow (rate) is zero after 3.5 hours
allow 'it’ for rate
3
(d)
more nitrate ions are absorbed in the presence of oxygen
allow nitrate ions absorbed faster in the presence of oxygen
1
(which suggests) they are absorbed by active transport / uptake
1
which requires energy from respiration
do not accept energy produced / created / made
1
some nitrate ions absorbed by diffusion
or
some nitrate ions absorbed (by active transport / uptake) requiring energy from anaerobic respiration
or
some nitrate ions absorbed by active transport / uptake using oxygen already dissolved in the solution
1
(e)
nitrate ions are used with glucose
1
to form amino acids
1
Page 33 of 46
(which are) used to synthesise proteins (needed for growth)
1
[18]
Q4.
(a)
to control for the starting mass (of the pieces of carrot)
allow because the pieces of carrot were not all the same mass at
the start
do not accept were not all the same size
do not accept as a control variable
1
(b)
suitable scale and label for y-axis
allow 5 or 6 per 2 cm
do not accept 5 per 1 cm
1
all points plotted correctly
allow ± ½ a square
allow 1 mark for 4 correct points
2
line of best fit
conc. …
percentage
(%) change…
0.0
+24
0.2
+12
0.4
+1
0.6
−8
0.8
−15
1
(c)
value from student’s line of best fit
allow ± ½ a square
1
(d)
mass decreased
1
(due to) loss of water by osmosis
ignore diffusion
1
through a partially / selectively / semi permeable membrane
1
a clear reference to concentration of water or concentration of sugar
is required for the fourth mark
(as) concentration of sugar solution is greater than concentration of sugar (solution) inside cells / carrot
allow (as) concentration of sugar solution inside cells / carrot is
lower than the concentration of sugar solution (in the tube or around
the carrot)
or
(as) the concentration of water is less outside the cells / carrot than the concentration inside the cells / carrot
allow answers in terms of dilute and concentrated solutions
1
(e)
the (partially permeable / cell) membrane was damaged
allow idea that cell membrane is no longer intact
or is more permeable / leaky
allow the membrane is denatured
ignore cells are dead
Page 34 of 46
1
[11]
Q5.
(a)
mineral / nitrate ion
allow nitrates
allow potassium / magnesium / sodium ion
do not accept nitrogen
1
(because) it is more concentrated inside the cell
allow converse
1
(so) it is moving against / up the concentration gradient
ignore moving along concentration gradient
allow from low concentration to high concentration
or
(so must) be moving by active transport / uptake
1
(b)
cell contents are more concentrated than the 0.2 (mol/dm3) solution
allow more dilute solution outside the cell
allow higher concentration of water outside of the cells
1
(therefore) water moves into the cells by osmosis
allow water moves into the cells by diffusion
do not accept active transport
1
the cells on the inner edge swell with water
allow cells on the inner edge become turgid
allow cells on the inner edge absorb water and expand
1
(but) the cells on the outer edge absorb less / no water so the stem curls
allow cells on outer edge absorb water at a slower rate
allow cells on outer edge cannot expand and therefore the stem
curls
1
(c)
between 0.2 and 0.4 (mol/dm3)
allow answer in the range 0.21 to 0.39 (mol/dm3)
1
(d)
allow ecf from part (c)
at 0.2 (mol/dm3) plant cells are absorbing water and at 0.4 (mol/dm3) they are losing water
1
(so) same concentration is when there is no (net) gain or loss of water
or
(so) same concentration is when the stem is the same shape as the original
1
(e)
measure the mass before and after to work out mass gain / loss
allow calculate change in mass
1
plot percentage gain / loss on graph and see where the line intercepts 0% change
allow repeat using different concentrations until percentage change
in mass is zero
1
[12]
Page 35 of 46
Q8.
(a)
salivary glands, pancreas and small intestine
1
(b)
pH
allow acidity
allow hydrogen ion / H+ concentration
ignore alkalinity
do not accept Ph or ph
1
(c)
iodine solution / reagent would not turn black / blue-black
or
iodine solution / reagent would stay orange / brown
allow iodine solution / reagent would not turn dark blue / dark
purple
ignore iodine solution / reagent would not turn blue
1
(d)
6.8
allow answer in range 6.75 to 6.85
1
(e)
84 (seconds)
allow answer in range 82 to 86 (seconds)
1
(f)
View with Figure 2
tangent drawn at 40 seconds
max 3 marks if incorrect tangent drawn
1
eg
(rate =)
1
correctly calculated rate from their tangent in arbitrary units per second
(rate =) 0.0375 (arbitrary units per second)
1
correctly calculated rate in arbitrary units per min using their value for rate in arbitrary units per second
(0.0375 × 60 =)
2.25 (arbitrary units per minute)
if no other marks scored allow 1 mark for
5.25 (arbitrary units per minute)
1
(g)
Level 3: Relevant points (reasons/causes) are identified, given in detail and logically linked to form a clear
account.
5−6
Level 2: Relevant points (reasons/causes) are identified, and there are attempts at logical linking. The
resulting account is not fully clear.
3−4
Level 1: Points are identified and stated simply, but their relevance is not clear and there is no attempt at
logical linking.
1−2
Page 36 of 46
No relevant content
0
Indicative content
•
•
•
•
•
•
•
enzymes are protein molecules
(so) have a 3D structure
lock and key theory
have an active site
(which) has a specific shape
shape of active site will only match shape of substrate
starch is substrate for amylase
•
•
•
•
•
•
at pH values above or below the optimum the shape of active site is changed (in some molecules)
(so) substrate can no longer fit the active site
(so) rate of digestion decreases
at extreme pH values enzyme is denatured
(so) shape of active site is changed
(so) amylase can no longer digest starch
Must refer to enzyme structure and effect of pH on enzyme molecule for Level 3
[15]
Q10.
(a)
to transfer energy
or
photosynthesis is an endothermic reaction
allow idea that light is the source of energy (for the reaction)
1
(b)
6CO2 + 6H2O → C6H12O6 + 6O2
1
(c)
allow the pondweed to equilibrate in the light
allow leave the pondweed in the light for 5 to10 minutes before
taking measurements
allow use the same concentration of sodium hydrogen carbonate
solution
ignore control carbon dioxide concentration unless method
described
ignore references to same intensity / distance of light or same
temperature
1
use a gas syringe / cylinder to measure the volume of oxygen / gas produced
do not accept carbon dioxide ignore references to counting bubbles
1
measure time oxygen / gas is collected for using a timer / stopwatch / stopclock
1
repeat the measurements (several) and calculate a mean
allow repeat the measurements (several) and discard anomalies
1
(d)
independent variable in student’s investigation is categoric
allow discrete
ignore discontinuous
1
independent variable in scientist’s investigation is continuous
1
ignore answers relating to the scale on the y-axis
(e)
492 to 577 (nm)
allow answers in range 475 to 650 (nm)
1
[9]
Page 37 of 46
Q11.
(a)
6CO2 + 6H2O ⟶ C6H12O6 + 6O2
1
(b)
endothermic
1
(c)
measure the volume of gas released
allow use a measuring cylinder / capillary tube / (gas) syringe
1
increase length of time
allow sensible length of time
allow video the investigation so you could re-count the bubbles later
allow repeat the measurement at each distance several times and
calculate a mean
ignore references to using other distances
1
(d)
temperature affects rate of photosynthesis
or
temperature affects rate of bubble production
allow correct description of effect of temperature on rate
1
(because) reaction / photosynthesis is controlled by enzymes
allow high temperatures denature enzymes
enzymes being denatured must be linked to high temperature
1
(e)
evidence of squaring for two distances that double:
25 and 100
or
100 and 400
1
calculate 1/d2 for two distances that double:
0.04 and 0.01
or
1/25 and 1/100
or
0.01 and 0.0025
or
1/100 and 1/400
allow 2 marks for these calculations without working
ignore calculations for a third distance as long as two where the
distance doubles are correct
1
(therefore as distance doubles) light intensity is quartered
1
(f)
2 (bubbles would be produced)
1
(as) very little light / energy for photosynthesis to occur
do not accept no light
1
allow 2 marks for a quarter of the bubbles are produced as light
distance doubles so 2 bubbles would be expected
(g)
(independent variable)
use different concentrations of sodium hydrogencarbonate solution
allow three concentration values
ignore different concentrations of carbon dioxide
1
(control variables)
max 2 marks for control variables
any two from:
•
distance from light source
Page 38 of 46
allow light intensity
ignore light unqualified
ignore same lamp
•
•
temperature of solution
same plant
allow type / size of plant
•
time for plant to equilibrate
allow time for plant to adjust to different solution
ignore time unqualified
2
[14]
Q15.
(a)
Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given.
5−6
Level 2: Some logically linked reasons are given. There may also be a simple judgement.
3−4
Level 1: Relevant points are made. They are not logically linked.
1−2
No relevant content.
0
Indicative content
advantages
•
doctors know about problems with the wound sooner
•
information to patient / doctor faster
•
can get information about wound without uncovering it
•
can apply antibiotics without uncovering wound
•
wound will heal sooner because not removing as often to check for infection
•
less chance of infection because not removing as often to check for infection
disadvantages
•
more expensive
•
needs a power source / battery / wireless signal
•
not readily available or cannot be bought in a chemist shop
•
not as easy to remove and clean
•
antibiotic from smart dressing may not be appropriate for that infection
•
could increase rate of evolution of antibiotic resistance
•
patient may panic unnecessarily
•
patient may have technical problems using phone, or no access to phone or signal
•
patient may have technical problems with sensor / electronics
•
doctor may receive more information than has time to deal with
both
•
keep pathogens out
•
reduce blood loss
•
allow helps platelets to clot blood
Answers with only advantages or only disadvantages limited to Level 1
[6]
Q16.
(a)
any one from:
•
(Type 2) diabetes
ignore obesity
•
•
•
•
do not accept Type 1 diabetes allow cardiovascular disease ignore
heart attack / failure
(coronary / ischaemic) heart disease / CHD
high blood pressure
cancer
depression
allow (osteo)arthritis
1
(b)
Page 39 of 46
27 =
1
height2 = 68.1 ÷ 27
or
height2 = 2.522(r) / 2.52 / 2.5
allow height =
or
allow height =
1
height = 1.59 (m) allow height =
allow a correctly rounded value
if 2.5 is given in step 2 allow an answer of 1.58 (m)
1
(c)
overweight
answer must be consistent with height calculated in (b)
1
(d)
any three from:
max 2 marks if refer to energy being made / used / produced /
created
allow reference to calories / joules for energy
•
increased energy intake if more food eaten
allow increased energy intake if more fat / carbohydrate eaten
allow converse
allow energy taken in when you eat
•
if exercise more, more energy is transferred / released
allow if exercise more, respiration / metabolism increases or is
faster
allow converse
allow energy is transferred during exercise
do not accept energy is burnt during exercise
•
if more energy is taken in than is transferred body mass increases
or
if less energy is taken in than is transferred body mass decreases
allow if less energy is transferred than is taken in body mass
increases
or
if more energy is transferred than is taken in body mass decreases
•
if energy intake = energy transferred body mass stays the same
if no marks are awarded allow 1 mark for food eaten can increase
body mass and exercise can decrease body mass
or
allow 1 mark for if a lot of food is eaten and little exercise is done
body mass increases
allow converse
3
(e)
Level 3: Relevant points (reasons/causes) are identified, given in detail and logically linked to form a clear
account.
5−6
Level 2: Relevant points (reasons/causes) are identified, and there are attempts at logical linking. The resulting
account is not fully clear.
3−4
Level 1: Points are identified and stated simply, but their relevance is not clear and there is no attempt at logical
linking.
1−2
Page 40 of 46
No relevant content
0
Indicative content
During exercise:
•
increased breathing rate
•
increased breath volume
•
(to) take in more oxygen for (aerobic) respiration
•
(and) exhale more carbon dioxide
•
increased heart rate
•
(so) increased blood flow (to muscles)
•
(to) transport oxygen / glucose to respiring cells faster
•
(and) increase rate of carbon dioxide removal
•
glycogen converted to glucose
•
•
•
•
•
insufficient oxygen supplied (during prolonged vigorous exercise)
(so) lactic acid is formed (during anaerobic respiration)
(and) an oxygen debt is created
(lactic acid causes) muscles become fatigued / tired or (causes) muscles to stop contracting efficiently
allow reference to sweating or increased body temperature or vasodilation (during or after exercise)
After exercise:
•
heart rate remains high or heart rate slowly decreases
•
continue to breathe rapidly or breathing rate slowly decreases
•
(to) pay back oxygen debt
•
oxygen debt is the amount of oxygen needed to break down lactic acid
•
(and to) provide more oxygen to react with the lactic acid and remove it from cells
•
(some) lactic acid transported to liver
•
(lactic acid) is converted back into glucose
For Level 3 need reference to:
•
changes during and after exercise
•
lactic acid and its removal.
[14]
Q17.
(a)
any one from:
•
through air / coughs / sneezes
•
touch of (same) surfaces / skin
1
(b)
gel / mucus (both) trap pathogens
need reference to both gel and mucus for maximum marks
allow spray / mucus (both) trap pathogens
1
gel / mucus will be moved by cilia
1
gel / mucus will be swallowed so pathogens will be killed in stomach acid
1
(c)
any one from:
•
do not know how long cold would last without the spray
•
•
allow immune response of different people varies
there are different strains / types of cold
difficult controlling conditions
allow named condition that is difficult to control, for example do not
know exactly when symptoms started
ignore placebo effect
1
(d)
any two from:
•
different ingredients have different roles
(some ingredients):
•
improve smell / taste
•
make other ingredients work
•
are disinfectants
•
are solvents
•
are lubricants
2
Page 41 of 46
(e)
any one from:
•
viruses living in cells can be the trigger for cancers
•
•
allow examples such as HPV virus and cervical cancer
immune reactions (initially caused by a pathogen) can trigger allergies / rashes / asthma
severe physical ill health can lead to depression or other mental illness
allow examples such as people with dementia becoming aggressive
or depressed
allow mental illness can lead to physical ill health
allow other examples, eg diabetes leading to heart disease
1
[8]
Q18.
(a)
platelets
1
(b)
increase in time taken for blood to clot
allow decrease in clotting of the blood
allow blood will not be able to clot
allow blood does not stop flowing out of cuts
1
(c)
5.1 ×109 per cm3
= 5.1 × 1012 per dm3
or
4.25 dm3 = 4250 cm3
1
5.1 × 1012 × 4.25
= 2.1675 × 1013
or
4250 × 5.1 × 109
= 2.1675 × 1013
allow correct calculation using incorrectly / not converted value from
step 1
1
1
= 0.92…(%)
1
(d)
(red blood cells) do not have chromosomes
ignore nucleus
allow (red blood cells) do not have DNA / genes
allow (red blood cells) do not have genetic material
1
(so chromosomes) cannot replicate and separate into two new cells
1
(e)
Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given.
5−6
Level 2: Some logically linked reasons given. There may also be a simple judgement.
3−4
Level 1: Relevant points are made. They are not logically linked.
1−2
No relevant content
0
Indicative content
(allow converse points if clearly referring to red blood cells from stem cells)
Blood donations advantages
•
it is an easier / quicker process
Page 42 of 46
•
•
•
•
•
•
•
blood can be donated / collected regularly so good supply
blood available for emergencies / immediately
can store blood longer than it takes to make (red) blood cells using stem cells
the components of the blood can be used for different treatments
the components of the blood can be used to treat more people / different people
known to work / tested treatment
free / inexpensive
disadvantages
•
relies on volunteers / donors
•
inconvenience / discomfort for donors
•
may not have enough blood / a regular supply of blood
•
may not have enough of the right blood component
•
blood may be wasted / not needed
•
risk of infection from donated blood
•
not patient’s own cells so may be rejected
For level 3 advantages and disadvantages supported by own knowledge
[14]
Q19.
(a)
D
1
(b)
C
1
(c)
right atrium → right ventricle → pulmonary artery
1
(d)
Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given.
5−6
Level 2: Some logically linked reasons are given. There may also be a simple judgement.
3−4
Level 1: Relevant points are made. They are not logically linked. 1‒2 AO1
1−2
No relevant content
0
Indicative content
Advantages of statins
•
•
•
•
•
easy to take or not invasive (procedure)
decrease blood cholesterol
slow down build-up of fatty materials in arteries
maintain blood flow to heart muscle cells
low cost (compared to stent operation)
Disadvantages of statins
•
•
•
•
might be side effects of drug eg muscle pain
effects take time to happen
drug will need to be taken long term
might forget to take drug
Advantages of stent
•
•
•
•
•
blocked artery is held open
blood flow to heart muscle cells is increased
stent will remain in place for a long time
effect of stent is immediate
rapid recovery from operation
Disadvantages of stent
•
•
•
risk of infection from operation
risk of surgery eg heart attack or bleeding
risk of thrombosis or blood clot
Page 43 of 46
For Level 3, arguments for and against both treatments are needed.
(e)
heart (muscle) cannot contract / pump as effectively / powerfully
allow heart (muscle) is not as strong
1
(so) less blood pumped out of heart or to body (on each beat / contraction)
ignore reference to rate of blood flow
1
(so) less oxygen (reaches cells / body) for (aerobic) respiration
allow (so) more anaerobic respiration
1
(so) breathing rate increases to supply more oxygen
or
(so) breathing rate increases to repay oxygen debt
allow (so) breathing rate increases to break down lactic acid
1
(f)
stem cells are undifferentiated cells
allow stem cells can differentiate
allow stem cells can develop into different types of cell
ignore stem cells can become specialised
ignore stem cells are not specialised
1
(therefore) can form heart (muscle) cells
allow (therefore) can form muscle cells
1
(g)
any two from:
•
cells will not be rejected
allow converse if clearly referring to embryonic stem cells
•
no risk of damage to embryo
allow no (potential) human life destroyed / damaged
•
adult can give consent
ignore unethical unqualified
ignore religion unqualified
2
[17]
Q20.
(a)
measure the volume of oxygen produced in a given time
or
when more oxygen is produced in a given time the rate of photosynthesis is faster
a reference to rate is needed
allow gas for oxygen
allow when oxygen is produced faster the rate of photosynthesis is
faster
ignore the faster the rate of photosynthesis, the more oxygen is
produced
allow the slower the oxygen is produced the slower the rate of
photosynthesis
or
less oxygen being produced in a given time, the slower the rate of
photosynthesis
1
(b)
light (intensity)
ignore temperature
1
(c)
20 000 (lux)
Page 44 of 46
allow answers in range 19 500 to 20 500 (lux)
1
(d)
there is a cost for heating the greenhouse
1
there is a cost for increasing the carbon dioxide in the
atmosphere (of the greenhouse)
allow there is a cost for lighting (in winter)
1
(therefore) the additional costs might exceed the (additional) sale price / profit
or
(additional) costs could not be recovered by increasing the sale price of the tomatoes
ignore these additional costs would reduce profits unqualified
1
(e)
when there is no light there is no photosynthesis
1
(so) no oxygen is produced
1
(but) respiration happens (all the time) and oxygen is used
1
(therefore) the net / overall oxygen production is negative / - 2 (arbitrary units)
do not accept an answer of -2 (arbitrary units)
unqualified
1
[10]
Q21.
(a)
D
1
any one from:
•
•
has chloroplasts
has a (large) vacuole
ignore has a (cell) wall
1
(b)
B
1
does not have a (cell) wall
allow has only a nucleus, (cell) membrane and cytoplasm
1
(c)
C
1
any one from:
•
genetic material is not in a nucleus
•
allow no nucleus
has a single loop of DNA
1
(d)
real size = 25 / 100 000
1
0.00025
1
(conversion to) 0.25 (µm)
allow 0.25 (µm) with no working shown for 3 marks
1
[9]
Page 45 of 46
Q22.
(a)
1
1
1
1
(b)
1.5:0.125 and 6:1
1
converted to same scale for example
12:1 and 6:1
or
6:0.5 and 6:1
allow 1.5:0.125 and 1.5:0.25
or
allow 1.5:0.125 and 0.75:0.125
1
as the length of the side of the cube increases the surface area to volume ratio decreases
allow size for length of side
allow converse
1
(c)
animal has a small(er) surface area to volume ratio (than a bacterium)
allow converse
1
(so) diffusion distance is larger in animals
or
volume to be supplied (with gas) by each unit of surface area is greater
allow converse
1
(therefore)
diffusion would not supply enough oxygen for the volume / size
or
diffusion would not remove enough carbon dioxide for the volume / size
or
diffusion rate per unit volume is slower
allow converse
1
(d)
active transport requires energy because (sugar molecule) movement is from low concentration (outside cell)
to high concentration (inside cell)
allow active transport requires energy because (sugar molecule)
movement is against / up concentration gradient
1
(this) energy is transferred by respiration which requires oxygen
1
(and a) higher concentration of oxygen allows a faster (rate of) respiration (or energy transfer)
1
[13]
Page 46 of 46