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AQA A LEVEL BIOLOGY 7402/2 PAPER 2 QUESTION PAPER AND MARK SCHEME { MERGED} JANUARY 2025, Exams of Nursing

AQA A LEVEL BIOLOGY 7402/2 PAPER 2 QUESTION PAPER AND MARK SCHEME { MERGED} JANUARY 2025 COMPLETE AND UPDATED MOSTLY TESTED ALREADY GRADED A

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Download AQA A LEVEL BIOLOGY 7402/2 PAPER 2 QUESTION PAPER AND MARK SCHEME { MERGED} JANUARY 2025 and more Exams Nursing in PDF only on Docsity!

AQA A LEVEL BIOLOGY 7402/2 PAPER 2

QUESTION PAPER AND MARK SCHEME

{ MERGED} JANUARY 2025 COMPLETE

AND UPDATED MOSTLY TESTED

ALREADY GRADED A

Please write clearly in block capitals.

Centre number

Candidate number

Surname

Forename(s)

Candidate signature

I declare this is my own work.

A-level

BIOLOGY

Paper 2

WEDNESDAY 1 JANUARY 2025 Morning Time

allowed: 2 hours

Materials

For this paper you must have:

  • a ruler with millimetre measurements
  • a scientific calculator.

Instructions

  • Use black ink or black ball-point pen.
  • Fill in the boxes at the top of this page.
  • Answer all questions.
  • You must answer the questions in the spaces provided. Do not

write outside the box around each page or on blank pages.

  • If you need extra space for your answer(s), use the lined pages at the end of

this book. Write the question number against your answer(s).

  • Show all your working.
  • Do all rough work in this book. Cross through any work you do not

want to be marked.

Information

  • The marks for the questions are shown in brackets.
  • The maximum mark for this paper is 91.

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

  • 1

ng = 1 × 10

  • 9 g - 1 h for 8 days into each patient. 1

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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0 3F

Do not write outside the

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.

  • The scientists planted tomato seeds into a large number of pots containing

sterilised soil.

  • They added a culture of G. intraradices to 50% of the pots and 50% were left

untreated.

  • After the seeds had developed into seedlings (young plants), the seedlings from the

untreated and treated pots were planted into four separate large greenhouses

(glasshouses).

  • A very limited supply of water (water shortage) was provided to two of the

greenhouses. A sufficient supply of water ( no water shortage) was provided to the

other two greenhouses.

  • After 60 days, the scientists determined the mean mass of tomatoes (kg m

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

DO NOT WRITE ON THIS PAGE

ANSWER IN THE SPACES PROVIDED

box

Turn over ►

Do not write outside the

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]

G B

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

G G

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

Turn over for the next question

Turn over ►

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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

Turn over ►

Do not write outside the

3 Variation in flower colour is considered one of the factors involved in the evolution of the

following two species of monkeyflower.

  • Erythranthe lewisii (Great Purple Monkeyflower), which has pink flowers, is mostly

found at higher altitudes (1600 to 3000 metres) and attracts bumblebees.

  • Erythranthe cardinalis (Scarlet Monkeyflower), which has red flowers, is mostly

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

Do not write outside the Turn over for the next question

DO NOT WRITE ON THIS PAGE

ANSWER IN THE SPACES PROVIDED

box

Turn over ►

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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

Turn over ►

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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

DO NOT WRITE ON THIS PAGE

ANSWER IN THE SPACES PROVIDED

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

A 21.3 0.007

B 49.7 0.022

C 38.3 0.636

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

Turn over for the next question

Turn over ►

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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]

0 9 S

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]

Turn over for the next question

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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.