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AQA A LEVEL BIOLOGY 7402/2 PAPER 2 QUESTION PAPER AND MARK SCHEME { MERGED} JANUARY 2025 COMPLETE AND UPDATED MOSTLY TESTED ALREADY GRADED A
Typology: Exams
1 / 54
Please write clearly in block capitals.
Centre number
Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
For this paper you must have:
write outside the box around each page or on blank pages.
this book. Write the question number against your answer(s).
want to be marked.
For Examiner’s Use
3 4 5 6 7 8 9
10
TOTAL
Question Mark
1
2
Do not write
Answer all questions in the spaces provided.
outside the box
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 cm of the chlorophyll solution
Describe how she could use these materials to separate the photosynthetic
pigments by chromatography.
[4 marks]
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]
Do not write outside the
1 Glutamate is a neurotransmitter involved in the transmission of nerve impulses from 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.
box
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.
2 Suggest two reasons why the patients had ziconotide injected into their
cerebrospinal fluid rather than taking a pill containing the drug.
[2 marks]
Question 2 continues on the next page
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3 Ziconotide was injected at 3 ng kg
ng = 1 × 10
box
Calculate the total mass in grams of ziconotide injected after 8 days into a patient
with a body mass of 82 kg
Show your working.
[2 marks]
Answer g
4 When the patients recorded the intensity of pain, suggest two reasons why it was
important to use a statistically valid scale.
[2 marks]
Do not write outside the igure 1 shows part of a phosphorus cycle, including the mass of phosphorus in two
stores.
box
Figure 1
One teragram (Tg) is 1 × 10
grams.
The supply of phosphorus to the soil is shown as a percentage of the total
phosphorus mass of each store.
1 Calculate in teragrams the difference in the supply of phosphorus to the soil from the
two stores shown in Figure 1.
Show your working.
[2 marks]
Answer Tg
Question 3 continues on the next page
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Water shortage can inhibit crop production. Scientists investigated the effect of the
mycorrhizal species Glomus intraradices on the growth of tomato plants under
conditions of water shortage and no water shortage.
sterilised soil.
untreated.
untreated and treated pots were planted into four separate large greenhouses
(glasshouses).
greenhouses. A sufficient supply of water ( no water shortage) was provided to the
other two greenhouses.
from each greenhouse.
Greenhouse P – untreated seedlings with water shortage
Greenhouse Q – treated seedlings with water shortage
Greenhouse R – untreated seedlings with no water shortage
Greenhouse S – treated seedlings with no water shortage
Treated seedlings are plants grown with G. intraradices.
Figure 2 shows the scientists’ results.
The error bars represent ± 2 standard deviations from the mean, which
includes over 95% of the data.
box
Figure 2
Do not write outside the
. 2 Using all the information, evaluate the effectiveness of using mycorrhizae to increase
crop production under conditions of water shortage and no water shortage.
[5 marks]
Turn over ►
0 3^ box
Do not write outside the
3 The tomato seeds were planted into sterilised soil.
Suggest two reasons why the soil was sterilised.
[2 marks]
box
4 The soil used in this investigation had the recommended concentration of fertiliser.
Suggest two reasons why the soil contained the recommended concentration of
fertiliser.
[2 marks]
Do not write outside the Turn over for the next question
box
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0 4 I
X X Ff X Yff
n cats, males are XY and females are XX. A gene on the X chromosome controls fur
colour in cats. The allele G codes for ginger fur and the allele B codes for black fur.
These alleles are codominant. Heterozygous females have ginger and black
patches of fur and their phenotype is described as tortoiseshell female.
The two alleles, F and f of a different gene, which is not sex-linked, interact with the
gene controlling fur colour. The allele F is dominant and stops the formation of
pigment in the fur, resulting in white fur. The allele f is recessive and has no effect on
fur colour.
box
1 Name the type of interaction between the two genes affecting fur colour.
[1 mark]
2 What phenotype would a cat with the following genotype have?
[1 mark]
X X ff
3 Complete the genetic diagram to show all the possible genotypes and the ratio of
phenotypes expected in the offspring of this cross.
Genotypes of parents
x
B
[3 marks]
Genotypes of offspring
Phenotypes of offspring
Ratio of offspring phenotypes
Do not write outside the
4 In a population, 36% of cats had the F allele and had white fur.
Use the Hardy–Weinberg equation to calculate the frequency of the f allele in
this population.
Show your working.
box
[2 marks]
Answer
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1 Figure 3 shows the wavelengths of light absorbed by three types of
photoreceptor found in the human retina.
Figure 3
Use Figure 3 and your knowledge of colour vision to explain how an orange
colour is seen at 600 nm
[3 marks]
0 5.^ box
Do not write outside the
2 Which of the following statements is associated with high sensitivity to light in
the retina?
✓
Tick ( ) one box.
[1 mark]
box
A single photoreceptor connecting to one neurone and spatial summation
A single photoreceptor connecting to one neurone and temporal summation
Several photoreceptors connecting to one neurone and spatial summation
Several photoreceptors connecting to one neurone and temporal summation
Question 5 continues on the next page
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3 Variation in flower colour is considered one of the factors involved in the evolution of the
following two species of monkeyflower.
found at higher altitudes (1600 to 3000 metres) and attracts bumblebees.
found at lower altitudes (up to 2000 metres) and attracts hummingbirds.
Bumblebees and hummingbirds are important in the pollination of flowers.
Pollination involves the transfer of male gametes to female gametes.
Explain the different processes that may have been involved in the evolution of these
two species of monkeyflower. Use the information provided to justify your answer.
[5 marks]
box
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box
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1 Describe and explain how three features of the cells in the proximal convoluted
tubule allow the rapid reabsorption of glucose into the blood.
[3 marks]
box
2 Antidiuretic hormone (ADH) binds to V receptors found in cell-surface membranes in two
parts of a nephron.
Name the two parts of a nephron where V receptors are found.
[1 mark]
3 V receptors only bind with ADH.
Suggest and explain why.
[2 marks]
Do not write outside the
4 A decrease in blood pressure stimulates the release of ADH.
Give the location of the receptors that detect a decrease in blood pressure
and explain how the release of ADH will affect blood pressure.
[3 marks]
box
Location
Explanation
Turn over for the next question
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1 In the following passage, the numbered spaces can be filled with biological terms.
An ecosystem supports a certain size of population of a species, called
Write the correct biological term beside each number below that matches the space in
the passage.
box
[2 marks]
2 Suggest two reasons for conserving rainforests.
[2 marks]
3 Give three reasons for the low efficiency of energy transfer from secondary
consumers to tertiary consumers in an ecosystem.
[3 marks]
the (1) capacity. There are often numerous habitats within an ecosystem.
Within a habitat, a species occupies a (2) governed by an adaption to
both (3) and biotic conditions. Populations of different species form
a (4).
Do not write outside the Turn over for the next question
box
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1 The KRAS gene codes for a protein called K-Ras. The protein relays signals from
outside a cell to a cell’s nucleus, stimulating cell division. An alteration in the KRAS
gene produces an oncogene which can cause a tumour to develop.
Suggest and explain how an alteration in the KRAS gene can cause a tumour to
develop.
box
[3 marks]
2 Alterations in the KRAS gene can cause colorectal cancer (CRC). Scientists
investigated the survival time of the following three groups of CRC patients who had
type II diabetes.
Group A – received no drug to treat type II diabetes
Group B – received the drug metformin to treat type II diabetes
Group C – received a combination of drugs (including metformin) to treat
type II diabetes
The scientists used a statistical test to compare the survival time of these patients
with CRC patients with no history of type II diabetes.
Do not write outside the Table 1 shows some of the results obtained by the scientists.
Table 1
Group
Mean survival time of
Probability value (P) CRC patients / months
No history of
type II diabetes
Using the information provided, what can you conclude about the effects of type II
diabetes and the different drug treatments on the survival time of CRC patients?
[5 marks]
box
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hort tandem repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs. STRs
are repeated a number of times, one after another. For example, the STR D5S818 is
made up of AGAT repeated 7 to 16 times.
STRs are found throughout the whole genome.
The repeated sequences in STRs are common to all humans. Due to variation in the
number of repeats, STRs can be used in genetic fingerprinting.
box
1 Describe how STRs could be removed from a sample of DNA.
[2 marks]
2 Genetic fingerprinting using STRs requires amplification of the STRs using the
polymerase chain reaction (PCR). The short base sequences either side of a specific
STR are known.
Explain the importance of knowing these base sequences in PCR.
[2 marks]
Do not write outside the
3 A single STR molecule consisting of a 12 base pair sequence of AGAT was amplified 50
times using PCR.
Calculate the total number of base pairs in all the STR molecules after 50
cycles of PCR.
Show your working.
box
[2 marks]
Answer
4 During genetic fingerprinting, the different STRs are separated by gel electrophoresis.
Give two features of STRs which enable them to be separated by gel electrophoresis.
[2 marks]
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ATP is essential for muscle contraction. The concentration of ATP in skeletal
muscle is approximately 5 × 10
mmol g
. During maximum exercise, ATP in
skeletal muscle is used at a rate of approximately 3.7 mmol kg
s
. If ATP
was not resynthesised, maximum exercise would last a short time.
Some studies have suggested that taking creatine supplements can improve 5
muscle performance during intense short-term exercise. Eating more
carbohydrate, known as ‘carbohydrate loading’, for a few days before exercise
can improve muscle performance when exercising for a long time.
During aerobic exercise, calcium ions in muscle cells have several roles.
They activate the inclusion of glucose transport proteins, GLUT4, in the 10 cell-
surface membrane and the inclusion of fatty acid transport proteins, CD36,
in mitochondrial membranes. An increase in muscle activity increases the
concentration of carbon dioxide in the blood. This causes an increase in
heart rate.
Use the information in the passage and your own knowledge to answer the
following questions.
box
. 1 ATP is essential for muscle contraction (line 1).
Describe the roles of ATP in muscle contraction.
[2 marks]
2 Calculate how long maximum exercise would last if ATP was not resynthesised
(lines 3–4).
[1 mark]
Answer s
1 0 Read the following passage.