Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signatu re
A-level
BIOLOGY
Paper 2
Prediction
Morning 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
2
Instructions
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.
9
Do all rough work in this book. Cross through any work you do not want
to be marked. 10
TOTAL
Information
The marks for the questions are shown in brackets.
The maximum mark for this paper is 91.
, Tg, 0.1% release) vs. biomass (200 Tg, 5%
Question 1: Chromatography & Photosynthetic Pigments release).
1.1 A student used thin-layer chromatography (TLC) to separate [2 marks]
pigments in spinach leaves. She had: Answer:
TLC plate Rocks: 1 Tg; Biomass: 10 Tg → Difference
Capillary tube = 9 Tg.
Solvent (acetone:petroleum ether, 3:7)
Ruler 3.2 Evaluate the effect of mycorrhizae
Describe the steps she should follow to separate the pigments. (Glomus) on tomato yield under drought
[4 marks] (Figure 2).
1. Draw a pencil baseline 1 cm from the bottom of the TLC [5 marks]
plate. Drought: Treated plants (Q) had
2. Spot concentrated pigment extract using a capillary tube 2.5× higher yield than untreated (P)
(small, dry spots). (p < 0.05).
3. Place the plate in a sealed tank with solvent (depth < No drought: Minimal difference (R
baseline). vs. S).
4. Remove when solvent front nears the top; mark the front Conclusion: Mycorrhizae enhance
and calculate Rf values. water/nutrient uptake only in stress.
Rationale: Ensures even separation and prevents solvent
evaporation. 3.3 Why sterilise soil?
[2 marks]
1.2 Using a polar solvent (e.g., ethanol), the student separated 4 1. Eliminate native
pigments. With a non-polar solvent (e.g., hexane), she separated 6 microbes confounding results.
pigments. Explain why. 2. Prevent competition with Glomus.
[2 marks]
Polar solvents dissolve polar pigments (e.g., chlorophyll b) 3.4 Why use recommended fertiliser?
less effectively, reducing separation. [2 marks]
Non-polar solvents better dissolve non-polar pigments 1. Control variable to isolate
(e.g., carotenes), resolving more bands. mycorrhizal effects.
2. Avoid nutrient limitation masking
Question 2: Neurotransmission & Drug Action symbiosis benefits.
2.1 Tetrodotoxin (TTX) is a neurotoxin that blocks voltage-gated
sodium channels. Explain how TTX prevents action potentials. Question 4: Genetics of Fur Colour
[5 marks] 4.1 Type of gene interaction?
1. TTX binds to Na⁺ channels, preventing Na⁺ influx. [1 mark]
2. Threshold potential is not reached → no depolarisation. Answer: Epistasis (F masks G/B).
3. Propagation of action potentials along axons stops.
4. Synaptic vesicles cannot release neurotransmitters. 4.2 Phenotype of XᴳXᴮff?
5. Pain signals are not transmitted to the brain. [1 mark]
Rationale: Detailed mechanism linking ion channels to signal Answer: Tortoiseshell (codominant G/B).
transmission.
4.3 Genetic diagram for XᴳXᴳFf × XᴮYff:
2.2 TTX is administered intravenously, not orally. Suggest two [3 marks]
reasons. Genotypes XᴮY XᴮYf
[2 marks] XᴳYFf
1. Digestive enzymes would break down the peptide toxin. XᴳF XᴳXᴮFf (white)
(white)
2. Faster absorption into the bloodstream via IV. XᴳXᴮff XᴳYff
Xᴳf
(tortoiseshell) (ginger)
2.3 A patient receives TTX at 2 µg/kg/hour for 12 hours (mass = 75 Phenotypic
kg). Calculate the total dose. ratio: 1 white : 1
[2 marks] tortoiseshell : 1
Answer: ginger.
2 µg × 75 kg × 12 h = 1800 µg (1.8 mg).
2.4 Pain intensity was recorded using a visual analogue scale
(VAS). Why is this valid?
[2 marks]
1. Standardised for comparison across patients.
2. Quantifiable (0–10 scale) for statistical analysis.
Question 3: Nutrient Cycles & Mycorrhizae
3.1 Calculate the difference in phosphorus flux from rocks (1000
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 . 1 A student used chromatography to separate the different photosynthetic pigments in a
chlorophyll solution. She had the following materials.
Chromatography paper
A ruler and pencil
Suitable glassware
A solvent (solvent A)
2 cm3 of the chlorophyll solution
Describe how she could use these materials to separate the photosynthetic pigments
by chromatography.
[4 marks]
0 1 . 2 Using solvent A, the student separated five pigments. She then repeated her method
using a different solvent, B. Using solvent B, she separated six pigments.
Explain the difference between these results.
[2 marks]
6
, 3
Do not write
outside the
0 2 . 1 Glutamate is a neurotransmitter involved in the transmission of nerve impulses from box
pain receptors to the brain. Ziconotide is a drug that can reduce severe, constant
pain. Ziconotide blocks the calcium ion channels at some of the synapses which use
glutamate.
The transmission of glutamate at synapses is similar to that of acetylcholine.
Explain how ziconotide reduces severe, constant pain.
[5 marks]
Ziconotide is a polypeptide and acts on synapses in the spinal cord. Scientists
investigated the effectiveness of ziconotide in reducing severe, constant pain.
Ziconotide was injected into each patient’s cerebrospinal fluid that bathes the brain
and spinal cord. Patients recorded the intensity of their pain using a statistically
valid scale.
0 2
. 2 Suggest two reasons why the patients had ziconotide injected into their cerebrospinal
fluid rather than taking a pill containing the drug.
[2 marks]
1
2
Question 2 continues on the next page
Turn over ►
Centre number Candidate number
Surname
Forename(s)
Candidate signatu re
A-level
BIOLOGY
Paper 2
Prediction
Morning 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
2
Instructions
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.
9
Do all rough work in this book. Cross through any work you do not want
to be marked. 10
TOTAL
Information
The marks for the questions are shown in brackets.
The maximum mark for this paper is 91.
, Tg, 0.1% release) vs. biomass (200 Tg, 5%
Question 1: Chromatography & Photosynthetic Pigments release).
1.1 A student used thin-layer chromatography (TLC) to separate [2 marks]
pigments in spinach leaves. She had: Answer:
TLC plate Rocks: 1 Tg; Biomass: 10 Tg → Difference
Capillary tube = 9 Tg.
Solvent (acetone:petroleum ether, 3:7)
Ruler 3.2 Evaluate the effect of mycorrhizae
Describe the steps she should follow to separate the pigments. (Glomus) on tomato yield under drought
[4 marks] (Figure 2).
1. Draw a pencil baseline 1 cm from the bottom of the TLC [5 marks]
plate. Drought: Treated plants (Q) had
2. Spot concentrated pigment extract using a capillary tube 2.5× higher yield than untreated (P)
(small, dry spots). (p < 0.05).
3. Place the plate in a sealed tank with solvent (depth < No drought: Minimal difference (R
baseline). vs. S).
4. Remove when solvent front nears the top; mark the front Conclusion: Mycorrhizae enhance
and calculate Rf values. water/nutrient uptake only in stress.
Rationale: Ensures even separation and prevents solvent
evaporation. 3.3 Why sterilise soil?
[2 marks]
1.2 Using a polar solvent (e.g., ethanol), the student separated 4 1. Eliminate native
pigments. With a non-polar solvent (e.g., hexane), she separated 6 microbes confounding results.
pigments. Explain why. 2. Prevent competition with Glomus.
[2 marks]
Polar solvents dissolve polar pigments (e.g., chlorophyll b) 3.4 Why use recommended fertiliser?
less effectively, reducing separation. [2 marks]
Non-polar solvents better dissolve non-polar pigments 1. Control variable to isolate
(e.g., carotenes), resolving more bands. mycorrhizal effects.
2. Avoid nutrient limitation masking
Question 2: Neurotransmission & Drug Action symbiosis benefits.
2.1 Tetrodotoxin (TTX) is a neurotoxin that blocks voltage-gated
sodium channels. Explain how TTX prevents action potentials. Question 4: Genetics of Fur Colour
[5 marks] 4.1 Type of gene interaction?
1. TTX binds to Na⁺ channels, preventing Na⁺ influx. [1 mark]
2. Threshold potential is not reached → no depolarisation. Answer: Epistasis (F masks G/B).
3. Propagation of action potentials along axons stops.
4. Synaptic vesicles cannot release neurotransmitters. 4.2 Phenotype of XᴳXᴮff?
5. Pain signals are not transmitted to the brain. [1 mark]
Rationale: Detailed mechanism linking ion channels to signal Answer: Tortoiseshell (codominant G/B).
transmission.
4.3 Genetic diagram for XᴳXᴳFf × XᴮYff:
2.2 TTX is administered intravenously, not orally. Suggest two [3 marks]
reasons. Genotypes XᴮY XᴮYf
[2 marks] XᴳYFf
1. Digestive enzymes would break down the peptide toxin. XᴳF XᴳXᴮFf (white)
(white)
2. Faster absorption into the bloodstream via IV. XᴳXᴮff XᴳYff
Xᴳf
(tortoiseshell) (ginger)
2.3 A patient receives TTX at 2 µg/kg/hour for 12 hours (mass = 75 Phenotypic
kg). Calculate the total dose. ratio: 1 white : 1
[2 marks] tortoiseshell : 1
Answer: ginger.
2 µg × 75 kg × 12 h = 1800 µg (1.8 mg).
2.4 Pain intensity was recorded using a visual analogue scale
(VAS). Why is this valid?
[2 marks]
1. Standardised for comparison across patients.
2. Quantifiable (0–10 scale) for statistical analysis.
Question 3: Nutrient Cycles & Mycorrhizae
3.1 Calculate the difference in phosphorus flux from rocks (1000
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 . 1 A student used chromatography to separate the different photosynthetic pigments in a
chlorophyll solution. She had the following materials.
Chromatography paper
A ruler and pencil
Suitable glassware
A solvent (solvent A)
2 cm3 of the chlorophyll solution
Describe how she could use these materials to separate the photosynthetic pigments
by chromatography.
[4 marks]
0 1 . 2 Using solvent A, the student separated five pigments. She then repeated her method
using a different solvent, B. Using solvent B, she separated six pigments.
Explain the difference between these results.
[2 marks]
6
, 3
Do not write
outside the
0 2 . 1 Glutamate is a neurotransmitter involved in the transmission of nerve impulses from box
pain receptors to the brain. Ziconotide is a drug that can reduce severe, constant
pain. Ziconotide blocks the calcium ion channels at some of the synapses which use
glutamate.
The transmission of glutamate at synapses is similar to that of acetylcholine.
Explain how ziconotide reduces severe, constant pain.
[5 marks]
Ziconotide is a polypeptide and acts on synapses in the spinal cord. Scientists
investigated the effectiveness of ziconotide in reducing severe, constant pain.
Ziconotide was injected into each patient’s cerebrospinal fluid that bathes the brain
and spinal cord. Patients recorded the intensity of their pain using a statistically
valid scale.
0 2
. 2 Suggest two reasons why the patients had ziconotide injected into their cerebrospinal
fluid rather than taking a pill containing the drug.
[2 marks]
1
2
Question 2 continues on the next page
Turn over ►
