Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signatu re
I declare this is my own work.
A-level
BIOLOGY
Paper 1
Prediction
Wednesday 4 June 2025 Afternoon Time allowed: 2 hours
Materials
For Examiner’s Use
For this paper you must have:
a ruler with millimetre measurements Question Mark
a scientific calculator.
1
Instructions 2
Use black ink or black ball-point pen. 3
Fill in the boxes at the top of this page. 4
Answer all questions.
5
You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages. 6
If you need extra space for your answer(s), use the lined pages at the end of 7
this book. Write the question number against your answer(s). 8
Show all your working.
Do all rough work in this book. Cross through any work you do not want 9
to be marked. 10
TOTAL
Information
The marks for the questions are shown in brackets.
The maximum mark for this paper is 91.
, Explain the importance of the xylem being
01.1 Give the three structural features found in all virus particles kept open as a continuous tube. [3 marks]
and describe the function of one of these features. [2 marks] 1
___________________________________________ 2
___________________________________________ 3
___________________________________________ Function of
03.1 The human disease, malaria, is caused by
one named feature
infection with a single-celled eukaryotic
______________________________________________________
organism.
____
Figure 2 shows a diagram of Plasmodium
01.2 Explain why viruses are described as acellular and non-living. vivax, one of the species that can cause
[2 marks]
malaria.
Figure 2
01.3 Give one reason why antibiotics are not effective against
Other than the Golgi apparatus, name one
viruses. [1 mark]
structure in Figure 2 which shows that P.
vivax is a eukaryote. [1 mark]
02.1 Chitin is a polysaccharide. The chitin monomer is a β-glucose
molecule with one OH group replaced by an NHCOCH3 group.
03.2 Describe two functions of the Golgi
NHCOCH3 can be represented by N(Ac).
apparatus in a eukaryotic cell. [2 marks] 1
_____________________________________
Figure 1 shows the monomer that forms chitin and the chitin ______ 2
polymer. _____________________________________
______
Figure 1
03.3 What does Figure 3 suggest is the order
Chitin has a similar structure to cellulose.
of human migration out of Africa? Tick ()
one box.
Use Figure 1 to describe three ways the structure of chitin is similar
to the structure of cellulose. [3 marks] 1
• Europe, India, East Asia, Central America,
___________________________________________ 2
South America • India, East Asia, Europe,
___________________________________________ 3
South America, Central America • India,
___________________________________________
Europe, East Asia, Central America, South
America • South America, Central America,
Question 2 continues on the next page
East Asia, Europe, India
Turn over ►
[1 mark]
02.2 Chitin keeps the tracheae open in the tracheal system of gas
03.4 There are an estimated 229 million cases
exchange in an insect. Gas exchange does not occur in the tracheae.
of human malaria worldwide per year. 94% of
these cases are found in Africa, but are not
Explain the importance of one adaptation of the gas exchange
caused by P. vivax. P. vivax does cause 61%
surface in the tracheal system of an insect. [2 marks]
of the cases of human malaria outside Africa.
Use this information to calculate the number
of cases worldwide caused by P. vivax each
02.3 Lignin is a polymer found in the walls of xylem vessels in year. [1 mark]
plants. Lignin keeps the xylem vessel open as a continuous tube.
,Answer ____________________ cases of malaria 05.1 The student added 100 mm3 of each
bacterial culture from its glass bottle onto a
03.5 In Africa today, most of the human population are resistant to separate agar plate. She spread each bacterial
malaria caused by P. vivax. Use your knowledge of natural culture evenly over the agar using a spreader.
selection to explain why this resistance is so common in Africa. [4
marks] Describe the aseptic techniques she should
use. [3 marks]
04.1 Some hospital patients suffer from diarrhoea caused by 05.2 On each agar plate, the student cut a well
infection with the bacterium Clostridium difficile. The C. difficile (a hole) in the agar.
bacteria release toxins. These toxins cause the diarrhoea.
The well had a diameter of 6 mm. The student
The toxins damage the cells lining the ileum, causing them to lose added 50 mm3 of cinnamon oil into the well.
their microvilli. The damage to the cells reduces the absorption of Calculate the minimum depth of the well to
the products of digestion and reduces the absorption of water, allow the addition of 50 mm3 of cinnamon
resulting in diarrhoea. oil. Use the following equation in your
calculation:
Explain why the damage to the cells lining the ileum reduces
absorption of the products of digestion and why this reduces Volume of a cylinder = πr2 × l Use 3.14 as the
absorption of water. [3 marks] value for π. Show your working. [2 marks]
Answer ____________________ mm
Question 4 continues on the next page Question 5 continues on the next page
Turn over ► Turn over ►
04.2 The scientists suggest that the anti-toxin antibody could be Figure 5 shows what one of her plates looked
given to some patients as a form of passive immunity. like after 24 hours.
Use Figure 4 to suggest how this passive immunity would work and Figure 5
which patients should be offered this anti-toxin antibody. [3 marks]
The student measured the diameter of the
clear zone with no bacterial growth around
each well. She made these measurements to
the nearest whole mm
04.3 To be used as passive immunity treatment, the anti-toxin
antibody would be injected. If it was given by mouth, it would be Table 1 shows her results.
digested.
Table 1
Describe how the anti-toxin antibody would be digested. [3 marks]
Bacterial culture\tDiameter of clear zone /
mm Cinnamon oil\tPositive control\tNegative
control Bacillus spp.\t15\t14\t0
Staphylococcus aureus\t20\t17\t0 Listeria
Turn over for the next question monocytogenes\t18\t12\t0 Escherichia
coli\t16\t12\t0 Klebsiella spp.\t14\t12\t0
Turn over ► Median for all cultures\t\t\t0 Mean for all
cultures\t\t\t0 Standard deviation for all
cultures\t2.4\t2.2\t0
, 05.3 Suggest exactly what the student added to the wells to get the 07.2 The World Health Organisation (WHO)
positive control and negative control results. [2 marks] suggests that to avoid long-term health
effects, COHb concentrations should be kept
below 2.5%.
WHO recommends that people should not be
05.4 Complete Table 1 to show the median and mean diameters. [1 exposed to: •\tair with > 10 mg m–3 CO for
mark] more than 8 hours •\tair with > 30 mg m–3
CO for more than 1 hour.
05.5 The mean ± 2 standard deviations includes over 95% of the
data. Scientists have used a mathematical model to
calculate the exposure to carbon monoxide
Use this information to consider whether the standard deviations that would result in 2.5% COHb in both adults
suggest the differences in means are likely to be due to chance. and children.
Explain your answer, including at least one calculation. [2 marks] Table 2 shows the scientists’ results.
Table 2
Turn over for the next question Exposure duration at rest / hours\tCO
concentration in the air / mg m–3 resulting in
Turn over ► 2.5% COHb Child\tAdult 1\t31.2\t40.2
8\t9.6\t10.6
06.1 Define genome and proteome. [2 marks] Genome
______________________________________________________ The scientists suggest that the WHO
_______________________ Proteome recommendations for carbon monoxide
______________________________________________________ concentrations resulting in 2.5% COHb
_______________________ should be reduced.
06.2 Consider the accuracy and limitations of the early Evaluate the scientists’ conclusion. [3 marks]
classification of bacteria using the arrangement of flagella. [3
marks]
Turn over for the next question
07.1 Carbon monoxide (CO) is released during incomplete Turn over ►
combustion of fossil fuels.
08.1 Scientists investigated a drug called
Figure 7 shows the dissociation curve for oxyhaemoglobin when: MiTMAB as a treatment for cancer.
•\tnot exposed to CO •\texposed to CO such that 50% of the oxygen MiTMAB inhibits cytokinesis.
binding sites are occupied by CO (50% COHb).
Figure 8 shows drawings of cancer cells seen
Figure 7 with an optical microscope from a:
Using Figure 7, what can you conclude about how exposure to CO •\tsample treated with MiTMAB •\tcontrol
affects the loading and unloading of oxygen by haemoglobin? sample. Figure 8
Explain your answer. [3 marks] The cells in drawing A can be identified as
those treated with Mi
Centre number Candidate number
Surname
Forename(s)
Candidate signatu re
I declare this is my own work.
A-level
BIOLOGY
Paper 1
Prediction
Wednesday 4 June 2025 Afternoon Time allowed: 2 hours
Materials
For Examiner’s Use
For this paper you must have:
a ruler with millimetre measurements Question Mark
a scientific calculator.
1
Instructions 2
Use black ink or black ball-point pen. 3
Fill in the boxes at the top of this page. 4
Answer all questions.
5
You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages. 6
If you need extra space for your answer(s), use the lined pages at the end of 7
this book. Write the question number against your answer(s). 8
Show all your working.
Do all rough work in this book. Cross through any work you do not want 9
to be marked. 10
TOTAL
Information
The marks for the questions are shown in brackets.
The maximum mark for this paper is 91.
, Explain the importance of the xylem being
01.1 Give the three structural features found in all virus particles kept open as a continuous tube. [3 marks]
and describe the function of one of these features. [2 marks] 1
___________________________________________ 2
___________________________________________ 3
___________________________________________ Function of
03.1 The human disease, malaria, is caused by
one named feature
infection with a single-celled eukaryotic
______________________________________________________
organism.
____
Figure 2 shows a diagram of Plasmodium
01.2 Explain why viruses are described as acellular and non-living. vivax, one of the species that can cause
[2 marks]
malaria.
Figure 2
01.3 Give one reason why antibiotics are not effective against
Other than the Golgi apparatus, name one
viruses. [1 mark]
structure in Figure 2 which shows that P.
vivax is a eukaryote. [1 mark]
02.1 Chitin is a polysaccharide. The chitin monomer is a β-glucose
molecule with one OH group replaced by an NHCOCH3 group.
03.2 Describe two functions of the Golgi
NHCOCH3 can be represented by N(Ac).
apparatus in a eukaryotic cell. [2 marks] 1
_____________________________________
Figure 1 shows the monomer that forms chitin and the chitin ______ 2
polymer. _____________________________________
______
Figure 1
03.3 What does Figure 3 suggest is the order
Chitin has a similar structure to cellulose.
of human migration out of Africa? Tick ()
one box.
Use Figure 1 to describe three ways the structure of chitin is similar
to the structure of cellulose. [3 marks] 1
• Europe, India, East Asia, Central America,
___________________________________________ 2
South America • India, East Asia, Europe,
___________________________________________ 3
South America, Central America • India,
___________________________________________
Europe, East Asia, Central America, South
America • South America, Central America,
Question 2 continues on the next page
East Asia, Europe, India
Turn over ►
[1 mark]
02.2 Chitin keeps the tracheae open in the tracheal system of gas
03.4 There are an estimated 229 million cases
exchange in an insect. Gas exchange does not occur in the tracheae.
of human malaria worldwide per year. 94% of
these cases are found in Africa, but are not
Explain the importance of one adaptation of the gas exchange
caused by P. vivax. P. vivax does cause 61%
surface in the tracheal system of an insect. [2 marks]
of the cases of human malaria outside Africa.
Use this information to calculate the number
of cases worldwide caused by P. vivax each
02.3 Lignin is a polymer found in the walls of xylem vessels in year. [1 mark]
plants. Lignin keeps the xylem vessel open as a continuous tube.
,Answer ____________________ cases of malaria 05.1 The student added 100 mm3 of each
bacterial culture from its glass bottle onto a
03.5 In Africa today, most of the human population are resistant to separate agar plate. She spread each bacterial
malaria caused by P. vivax. Use your knowledge of natural culture evenly over the agar using a spreader.
selection to explain why this resistance is so common in Africa. [4
marks] Describe the aseptic techniques she should
use. [3 marks]
04.1 Some hospital patients suffer from diarrhoea caused by 05.2 On each agar plate, the student cut a well
infection with the bacterium Clostridium difficile. The C. difficile (a hole) in the agar.
bacteria release toxins. These toxins cause the diarrhoea.
The well had a diameter of 6 mm. The student
The toxins damage the cells lining the ileum, causing them to lose added 50 mm3 of cinnamon oil into the well.
their microvilli. The damage to the cells reduces the absorption of Calculate the minimum depth of the well to
the products of digestion and reduces the absorption of water, allow the addition of 50 mm3 of cinnamon
resulting in diarrhoea. oil. Use the following equation in your
calculation:
Explain why the damage to the cells lining the ileum reduces
absorption of the products of digestion and why this reduces Volume of a cylinder = πr2 × l Use 3.14 as the
absorption of water. [3 marks] value for π. Show your working. [2 marks]
Answer ____________________ mm
Question 4 continues on the next page Question 5 continues on the next page
Turn over ► Turn over ►
04.2 The scientists suggest that the anti-toxin antibody could be Figure 5 shows what one of her plates looked
given to some patients as a form of passive immunity. like after 24 hours.
Use Figure 4 to suggest how this passive immunity would work and Figure 5
which patients should be offered this anti-toxin antibody. [3 marks]
The student measured the diameter of the
clear zone with no bacterial growth around
each well. She made these measurements to
the nearest whole mm
04.3 To be used as passive immunity treatment, the anti-toxin
antibody would be injected. If it was given by mouth, it would be Table 1 shows her results.
digested.
Table 1
Describe how the anti-toxin antibody would be digested. [3 marks]
Bacterial culture\tDiameter of clear zone /
mm Cinnamon oil\tPositive control\tNegative
control Bacillus spp.\t15\t14\t0
Staphylococcus aureus\t20\t17\t0 Listeria
Turn over for the next question monocytogenes\t18\t12\t0 Escherichia
coli\t16\t12\t0 Klebsiella spp.\t14\t12\t0
Turn over ► Median for all cultures\t\t\t0 Mean for all
cultures\t\t\t0 Standard deviation for all
cultures\t2.4\t2.2\t0
, 05.3 Suggest exactly what the student added to the wells to get the 07.2 The World Health Organisation (WHO)
positive control and negative control results. [2 marks] suggests that to avoid long-term health
effects, COHb concentrations should be kept
below 2.5%.
WHO recommends that people should not be
05.4 Complete Table 1 to show the median and mean diameters. [1 exposed to: •\tair with > 10 mg m–3 CO for
mark] more than 8 hours •\tair with > 30 mg m–3
CO for more than 1 hour.
05.5 The mean ± 2 standard deviations includes over 95% of the
data. Scientists have used a mathematical model to
calculate the exposure to carbon monoxide
Use this information to consider whether the standard deviations that would result in 2.5% COHb in both adults
suggest the differences in means are likely to be due to chance. and children.
Explain your answer, including at least one calculation. [2 marks] Table 2 shows the scientists’ results.
Table 2
Turn over for the next question Exposure duration at rest / hours\tCO
concentration in the air / mg m–3 resulting in
Turn over ► 2.5% COHb Child\tAdult 1\t31.2\t40.2
8\t9.6\t10.6
06.1 Define genome and proteome. [2 marks] Genome
______________________________________________________ The scientists suggest that the WHO
_______________________ Proteome recommendations for carbon monoxide
______________________________________________________ concentrations resulting in 2.5% COHb
_______________________ should be reduced.
06.2 Consider the accuracy and limitations of the early Evaluate the scientists’ conclusion. [3 marks]
classification of bacteria using the arrangement of flagella. [3
marks]
Turn over for the next question
07.1 Carbon monoxide (CO) is released during incomplete Turn over ►
combustion of fossil fuels.
08.1 Scientists investigated a drug called
Figure 7 shows the dissociation curve for oxyhaemoglobin when: MiTMAB as a treatment for cancer.
•\tnot exposed to CO •\texposed to CO such that 50% of the oxygen MiTMAB inhibits cytokinesis.
binding sites are occupied by CO (50% COHb).
Figure 8 shows drawings of cancer cells seen
Figure 7 with an optical microscope from a:
Using Figure 7, what can you conclude about how exposure to CO •\tsample treated with MiTMAB •\tcontrol
affects the loading and unloading of oxygen by haemoglobin? sample. Figure 8
Explain your answer. [3 marks] The cells in drawing A can be identified as
those treated with Mi
