AQA GCSE Biology Paper 2 Higher June 2025 question paper 8461/2H

Ichthyosaurs are reptiles that lived in the sea millions of years ago.

Figure 1 shows the fossilised remains of an ichthyosaur.

Suggest how the fossil in Figure 1 was formed after the ichthyosaur died.

The length of the image of the ichthyosaur in Figure 1 is 120 mm.

The real length of the ichthyosaur was 17 times longer than the image in Figure 1.

Calculate the real length of the ichthyosaur.

Give your answer in metres.

Table 1 gives the classification of the ichthyosaur in Figure 1.

Complete Table 1.

Choose answers from the box.

Ichthyosaurs were predators.

Ichthyosaurs are now extinct.

Scientists think that extinction of the ichthyosaurs was caused by increased competition with other predators for food.

Suggest two other possible causes of extinction of the ichthyosaurs.

Students investigated how many daisy plants were growing in a field at different distances from a tree.

This is the method used.

1. Place a 20-metre tape measure on the ground, with the tree at 0 metres.

2. Place a 1 m² quadrat on the ground every 4 metres along the tape measure.

3. Count the number of daisy plants in each quadrat.

4. Take a soil sample from each quadrat to find the percentage of water in the soil.

Figure 2 shows the tree and the tape measure.

This is the method used for finding the percentage of water in each soil sample (step 4):

5. Weigh an empty container.

6. Place the soil sample in the container and weigh again.

7. Heat the container of soil in an oven at 100 °C for several hours.

8. Allow the container of soil to cool and weigh again.

9. Repeat steps 7 and 8 until there is no further change in mass.

Suggest why the students repeated steps 7 and 8 until there was no further change in mass.

Table 2 shows the results.

Calculate percentage X in Table 2.

Give your answer to the nearest whole number.

Describe the effect of distance from the tree on the percentage of water in the soil between 4 metres and 16 metres.

Use Table 2.

A student concluded:

‘As the water content of the soil increases, so does the number of daisy plants.’

Describe two changes to the investigation that would increase the validity of the student’s conclusion.

The percentage of water in the soil is an abiotic factor.

Suggest three other abiotic factors that might have caused more daisy plants to grow further away from the tree.

Do not refer to water in your answer.

Tropisms help plants survive.

What is geotropism?

Plan an investigation to find the effect of the direction of light on the growth of plant seedlings.

You may use the equipment shown in Figure 3 and any other laboratory equipment.

Plant responses are controlled by hormones.

Which hormone controls a plant’s response to the direction of light?

How does the hormone you named in Question 03.3 control the plant’s response to the direction of light?

Tick () one box.

Explain how a plant’s response to light helps the plant survive.

Human growth hormone (hGH) is made by the pituitary gland.

Name one other hormone made by the pituitary gland.

hGH is a protein.

A child with a deficiency of hGH can be given injections of hGH.

What would happen to the hGH if it was given as a tablet that was swallowed?

Scientists can use genetic engineering to make hGH.

Figure 4 shows a summary of the process.

Describe how scientists can transfer the gene for hGH from human cells to bacterial cells.

Use information from Figure 4.

Growth hormone (GH) can be extracted from the urine of farm animals.

It is better to use hGH made by genetic engineering than to use GH from the urine of farm animals.

Suggest two reasons why.

Do not refer to ethical reasons or religious beliefs in your answer

Peat bog is a specialised habitat for some living organisms.

Peat has been removed from peat bogs so that the land can be used for farming or forestry.

Give two uses of the peat removed from peat bogs.

The destruction of peat bogs can affect biodiversity.

What is meant by ‘biodiversity’?

Explain how the destruction of peat bogs can affect biodiversity:

• in the local area

• globally.

New cells are produced by cell division.

Figure 5 shows sperm formation in a human.

Which cell division in Figure 5 represents mitosis?

Tick () one box.

Which two cells in Figure 5 are genetically identical?

Tick () one box.

How many chromosomes are there in cell J in Figure 5 ?

How many of the cells C, D, E, F, G, H, I and J contain a Y chromosome?

Use Figure 5.

Strawberry plants can reproduce both sexually and asexually.

Figure 6 shows a strawberry plant reproducing:

• sexually using flowers, fruits and seeds

• asexually using horizontal stems called runners.

Explain why the offspring produced using runners are genetically identical.

Explain why the offspring produced using flowers, fruits and seeds are not genetically identical.

Describe two advantages of asexual reproduction for the survival of strawberry plants.

Describe two advantages of sexual reproduction for the survival of strawberry plants.

Two students investigated reaction time.

This is the method used.

1. Student A holds a metre rule just above student B ’s hand, as shown in Figure 7.

2. Student A lets go of the metre rule.

3. Student B catches the metre rule as quickly as possible.

4. Student A writes down the reading from the scale on the metre rule.

5. Students A and B repeat steps 1 to 4 another six times.

Table 3 shows the results.

What is the median result in Table 3 ?

Tick () one box.

Calculate student B ’s mean reaction time.

Use the equation:

Give your answer in milliseconds.

Give your answer to 3 significant figures.

Use data from Table 3.

The method and Figure 7 are repeated below.

1. Student A holds a metre rule just above student B ’s hand, as shown in Figure 7.

2. Student A lets go of the metre rule.

3. Student B catches the metre rule as quickly as possible.

4. Student A writes down the reading from the scale on the metre rule.

5. Students A and B repeat steps 1 to 4 another six times.

Describe two ways the students could improve the investigation.

Do not refer to repeating results in your answer.

Catching the rule was a response to a stimulus.

Describe how student B ’s response was coordinated by the nervous system.

Some people keep rabbits as pets.

Figure 8 shows two types of rabbit.

The Himalayan fur pattern is controlled by a dominant allele.

A heterozygous male Himalayan rabbit was crossed many times with each of two female Himalayan rabbits, A and B.

The results of the two types of cross were different.

• Crosses with female A: all of the 210 offspring were Himalayan rabbits.

• Crosses with female B: some of the 240 offspring were Himalayan rabbits and some were white rabbits.

In Questions 08.1 and 08.2, use the following symbols to represent alleles: H = dominant allele for Himalayan fur h = recessive allele for white fur.

What is the genotype of female Himalayan rabbit A ?

Give the reason for your answer.

Determine the probability that one of the offspring from a cross with female Himalayan rabbit B will be white.

You should:

• draw a Punnett square diagram

• use the symbols H and h

• identify the phenotype of each offspring genotype.

Probability of offspring being white =

Adult Himalayan rabbits have:

• white fur over most of the body

• black fur on the nose, ears and feet.

The black colour is caused by production of a substance called melanin.

Figure 9 shows how melanin is made from another substance called tyrosine.

Figure 9

White rabbits have one base change in the gene that codes for the enzyme tyrosinase.

Explain how a change of one base in the DNA of the gene coding for tyrosinase could stop the tyrosinase working.

For the first four weeks of life, Himalayan rabbits produce white fur over the whole body.

The black areas of fur start to develop after four weeks.

In the first four weeks, young rabbits stay in the nest with their mother.

A rabbit’s body temperature is 39 °C.

The tyrosinase in Himalayan rabbits is:

• most active between 15 °C and 25 °C

• not active above 35 °C.

The fur on the nose, ears and feet of Himalayan rabbits is white for the first four weeks of life.

Explain what causes the fur to be white in the first four weeks of life.

From the age of four weeks, young rabbits move from the nest to the outside environment.

Explain why a Himalayan rabbit develops black nose, ears and feet from the age of four weeks.

Melanin is also produced in human skin.

Melanin absorbs ultraviolet (UV) radiation from sunlight and prevents the radiation reaching deep into the skin.

UV radiation is a type of ionising radiation.

Explain the advantage of producing melanin in human skin when exposed to bright sunlight.

Type 2 diabetes is a condition that has become more common in recent years.

Scientists recorded the percentage of people of different ages who had Type 2 diabetes.

The people were in different weight categories:

• healthy weight

• overweight

• obese.

Figure 10 shows the results.

Give two conclusions from the results in Figure 10.

Two groups of scientists investigated the use of different drugs to treat

Type 2 diabetes.

In both investigations, the scientists measured the percentage of haemoglobin with glucose attached (Hb-G). This showed the long-term concentration of glucose in the blood.

Investigation 1:

The scientists injected drug A into 175 patients with Type 2 diabetes once each day for 12 weeks.

Table 4 shows the results.

Investigation 2:

631 patients with Type 2 diabetes took one tablet containing drug B each day. A control group of 630 patients took a placebo tablet each day.

The scientists measured the Hb-G in each patient’s blood at the start of the investigation and at 6-week intervals up to 24 weeks.

Figure 11 shows the results.

For the patients treated with drug B the mean percentage of Hb-G at the start was 8.3%.

What was the mean percentage of Hb-G after 12 weeks for the patients treated with drug B ?

Tick () one box.

In a person without diabetes, the Hb-G value is between 4.5% and 6%.

When treating patients with Type 2 diabetes, doctors think that an Hb-G value <7% is acceptable.

Evaluate:

• the methods used in the investigations

• the usefulness of drug A and drug B for controlling Type 2 diabetes.