AQA GCSE Trilogy Biology Paper 2 Higher June 2025 question paper 8464/B/2H

This question is about genetics.

The fur colour of rabbits is controlled by two alleles.

Draw one line from each term to the meaning of the term relating to genetics in rabbits.

In rabbits:

• the allele for brown fur (B) is dominant

• the allele for white fur (b) is recessive.

A rabbit with the alleles Bb and a rabbit with the alleles bb breed together.

Determine the probability that one of the offspring will have white fur.

You should:

• complete the Punnett square diagram

• identify any offspring that will have white fur.

A male rabbit is heterozygous for fur colour.

The rabbit’s body cells have the genotype Bb.

One of the sperm cells from the rabbit has the allele b.

Explain why the alleles in the rabbit’s body cells and the allele in the sperm cell are different.

Figure 1 shows the chromosomes of a rabbit.

How many chromosomes would be found in a skin cell of a rabbit?

Use Figure 1.

The sex of a rabbit is controlled in the same way as the sex of a human.

Give the evidence from Figure 1 that the rabbit is female.

This question is about the hormones involved in reproduction.

Name one hormone produced in the ovaries.

Give one function of the hormone that is produced in the testes.

Different methods of contraception can involve:

• barriers

• hormones.

Condoms are a barrier method of contraception.

Give one advantage of condoms as a method of contraception compared with hormonal methods of contraception.

Do not refer to cost in your answer.

Describe how hormones are used in different methods of contraception.

Buttercups are small plants.

Students investigated the distribution of buttercup plants at different distances from a tree.

Figure 2 shows quadrats being used to sample two areas.

What was the independent variable in this investigation?

Students counted every small square in the quadrat that was at least half covered by buttercup plants.

Determine the percentage cover of buttercup plants 10 metres away from the tree.

Use Figure 2.

The students placed:

• several quadrats 1 metre away from the tree

• several quadrats 10 metres away from the tree.

Give two factors the students should consider when deciding how many times to place a quadrat at each distance.

Do not refer to time available.

Figure 3 shows two different quadrats.

Explain two advantages of using quadrat B instead of quadrat A in the investigation.

You should include calculations in your answer.

A point quadrat can also be used to estimate the percentage cover of plants in an area.

Figure 4 shows a point quadrat.

When using a point quadrat, the pins are pushed down to the soil.

The number of pins that touch a buttercup plant is counted.

What are two advantages of using a point quadrat compared with using a square quadrat?

Tick () two boxes.

The percentage cover of buttercup plants can be estimated using the equation:

30 students each collected results from 50 pins.

The students then put all their results together.

Buttercup plants had a percentage cover of 7%.

Calculate the number of times a pin touched a buttercup plant.

Farmers can increase crop yield by controlling the conditions the plants grow in.

Maize is a crop plant.

A variety of maize has been genetically modified (GM) to be resistant to a herbicide.

Explain how growing GM herbicide-resistant maize can produce a larger yield than growing non-GM maize.

Explain how growing a GM herbicide-resistant crop can decrease the biodiversity of animals.

Bees are a type of insect.

The number of insects near a crop can be increased by planting hedgerows.

Increasing the number of bees and other insects increases crop yield.

Suggest two reasons why increasing the number of insects can increase crop yield.

Hedgerows provide habitats for insects.

Give one reason why increasing hedgerow habitats increases insect numbers.

Some farmland contains areas of peat.

When peat is dug up:

• the oxygen levels in the peat increase

• the peat decays quickly.

Explain why increasing the level of oxygen in peat contributes to climate change.

Plesiosaurs are extinct reptiles that lived in the ocean.

Figure 5 shows a fossil of a plesiosaur.

Plesiosaurs may have moved rapidly upwards to hold their heads above the water surface to search for prey.

What type of adaptation was the rapid upwards movement?

Give two biotic factors that may have caused the extinction of plesiosaurs.

Describe how the plesiosaur fossil in Figure 5 could have been formed.

Scientists use fossils to study evolution.

Suggest two reasons why scientists cannot study the mutations involved in the evolution of plesiosaurs.

Do not refer to extinction in your answer.

Table 1 shows part of the classification of a plesiosaur.

Complete Table 1.

Give the binomial name of the plesiosaur in Table 1.

The human body makes the hormone insulin and a chemical called C-peptide.

C-peptide concentration in the blood has a linear relationship with the amount of insulin the body produces.

Which equation represents a linear relationship?

Tick () one box.

When the body makes insulin, C-peptide is also made.

The concentration of C-peptide in the blood is not increased by insulin injections.

Some people with Type 2 diabetes are incorrectly told they have Type 1 diabetes.

Doctors can test the concentration of C-peptide in the blood to check which type of diabetes a person has.

Explain:

• how the test can indicate which type of diabetes a person has

• the importance of finding out whether a person being treated for Type 1 diabetes actually has Type 2 diabetes.

Glucagon is a hormone produced by the body.

Which organ produces glucagon?

Tick () one box.

In some people, glucagon is produced in smaller quantities than is needed.

Explain why people who do not produce enough glucagon feel weak and tired.