AQA GCSE Trilogy Biology Paper 2 Higher June 2024 question paper 8464/B/2H

Limpets are small animals with shells.

Limpets attach to rocks on sea shores.

Figure 1 shows limpets on rocks.

Limpets eat algae.

Limpets are prey for crabs.

Give the food chain for algae, crabs and limpets.

Students estimated the population of limpets on a sea shore.

The students were given a square quadrat.

Figure 2 shows the quadrat.

Calculate the area of the quadrat in m².

The total area of the sea shore was 1800 m².

The students sampled 2% of the total area of the sea shore.

Calculate the number of times the students needed to use the quadrat for the 2% sample.

Use your answer from Question 01.2

Explain why throwing a quadrat is not a random method to estimate population size.

Do not refer to safety in your answer.

Describe one method the students could use to plan where the quadrat should be randomly placed each time.

Suggest one hazard the students should be aware of when collecting data on the sea shore.

Do not refer to throwing quadrats in your answer.

Populations of limpets are monitored to assess the impact of pollution in water.

Suggest one type of pollution in water that may affect the population of limpets.

Potatoes are a food crop.

Potato plants are classified as eukaryota.

What type of classification group is eukaryota?

Tick () one box.

Potato plants can reproduce by asexual reproduction.

Which statement is true for asexual reproduction?

Tick () one box.

Flowers of potato plants contain gametes for sexual reproduction.

How is a gamete different from other cells in a potato plant?

Tick () one box.

Plants in the same genus as potatoes have been studied by scientists.

Describe one way a new plant species could be identified as being in the same genus as potatoes.

Scientists have collected and stored seeds from species in the same genus as potatoes.

In the future, these seeds may be used for genetic modification of potato plants.

Genetically modified potato plants could help supply food to the human population as the climate changes.

Explain why genetic modification of crop plants may be important for the human population to survive climate change.

AKU is a genetic disorder.

Figure 3 shows the inheritance of AKU in one family.

Describe how Figure 3 shows that the allele for AKU is recessive.

Which person is definitely heterozygous for AKU?

Tick () one box.

A female who has AKU and a male who is heterozygous for AKU plan to have a child.

Determine the probability that the child will have AKU.

You should:

• complete Figure 4

• identify the phenotype of each offspring genotype

• use the symbols: A = dominant allele a = recessive allele.

A mutation is a change in a gene.

People who have AKU have a mutation that causes the production of a non-functioning enzyme.

Enzymes are proteins.

Suggest how a mutation can result in the production of a non-functioning enzyme.

Some people have In Vitro Fertilisation (IVF) treatment to increase the chance of becoming pregnant.

Describe how the process of IVF can result in pregnancy.

Embryos can be screened to detect inherited disorders.

Give two arguments against embryo screening.

Do not refer to religion in your answer.

Rat populations can increase rapidly.

When rat populations are large there is competition between rats.

When rats compete, the basal metabolic rate of the rats increases.

Basal metabolic rate is controlled in the same way in humans and in rats.

Describe how basal metabolic rate is increased.

The size of a rat population can increase quickly.

One female rat and one male rat can produce 20 offspring every 2 months.

Warfarin is a poison that has been used to control rat populations.

Rat populations can become resistant to warfarin by the process of evolution.

A population of rats was given warfarin for 4 months.

Table 1 shows information about resistance to warfarin in the rat population for a year after warfarin was first given.

Rats with resistance to warfarin have a smaller mean mass than rats that

are not resistant to warfarin.

Smaller rats are often at a disadvantage when competing against larger rats.

Explain the trends in the data when warfarin was being given and when warfarin was no longer given.

Use Table 1.

Otters are mammals that live in river ecosystems.

Figure 5 shows an otter.

Define the term ‘ecosystem’.

Otters are an important species for the stability of the river community.

Describe two ways animal species may be important for the stability of a whole community.

Sewage was accidentally added to a river.

The sewage moved with the river water and affected:

• the number of bacteria in the water

• the concentration of dissolved oxygen in the water.

Samples of river water were analysed at different distances from where the sewage was added.

Table 2 shows the results.

The number of bacteria at 5.0 km was greater than the number of bacteria where the sewage was added.

Calculate how many times greater.

A student concluded:

‘number of bacteria concentration of dissolved oxygen’

Explain why the student’s conclusion is not correct.

Use Table 2.

Otters:

• live in water and on the land

• eat mainly fish.

The concentration of dissolved oxygen has decreased in a river where otters live.

Explain how the decrease in the concentration of dissolved oxygen in the river water will affect the population of otters.

Hormones are released from endocrine glands.

Which gland releases hormones to control other glands?

Tick () one box.

Several hormones can affect blood glucose concentration.

Adrenaline can increase blood glucose concentration.

What is one other effect of adrenaline?

Tick () one box.

Cells in the pancreas detect changes in blood glucose concentration.

What type of cell in the body detects changes?

Scientists investigated whether blood glucose concentration affects reaction time.

The reaction times of ten people with Type 1 diabetes were measured.

This is the method used.

1. Tell one person to drink a glucose solution.

2. Monitor the person’s blood glucose concentration.

3. Record the person’s reaction time when the person’s blood glucose concentration is:

16 mmol/dm³

6 mmol/dm³

3 mmol/dm³

4. Repeat steps 1 to 3 for the nine other people.

People with Type 1 diabetes were selected for the investigation instead of people who did not have diabetes.

Explain why.

Control variables between the different people in the investigation included:

• age

• sex

• food and drink consumed before and during the test.

Suggest two other control variables that should be used in the investigation.

It was important for the scientists to monitor the health of each person during the investigation.

Suggest one reason why.

Figure 6 shows the results.

People who do not have diabetes usually have a blood glucose concentration in the range of 4.0 mmol/dm³ to 7.8 mmol/dm³.

Describe how the results in Figure 6 show the importance of homeostasis.

Describe how blood glucose concentration is maintained within narrow limits in people who do not have diabetes.

The scientists gave the hypothesis:

‘Optimum blood glucose concentration increases the production of chemicals that diffuse across synapses.’

Describe how an increase in the chemicals could decrease reaction time.