AQA GCSE Biology Paper 2 Higher June 2024 question paper 8461/2H

Evolution of new species occurs by mutation and natural selection.

What is a mutation?

Describe the process of natural selection.

Which scientists suggested the theory of evolution by natural selection?

Tick () one box.

The hoverfly and the wasp are insects with bright yellow and black markings.

Figure 1 shows a hoverfly and a wasp.

The wasp has a sting to defend itself against predators.

The hoverfly does not have a sting.

Hoverflies and wasps live in the same habitat.

Explain how having yellow and black markings helps the hoverfly survive.

Peat bogs are estimated to contain twice as much carbon as all the world’s forests.

Figure 2 shows a section through part of a peat bog.

Layer A contains a lot of air.

Layer B:

• contains the dead remains of plants

• has a low pH

• contains very little oxygen

• contains carbon dioxide and methane.

Explain why most of the dead remains of plants in layer B do not decay.

The peat bog in Figure 2 is a stable community.

The moss produces biomass at a rate of 340 g/m²/year.

What is the approximate biomass of the moss that becomes biomass in primary

Tick () one box.

The sundew plant shown in Figure 2 on page 4 has leaves with sticky hairs that

trap and digest insects.

Digestion of the insects releases phosphates and simple compounds of nitrogen that are used by the sundew plant.

What substance can the sundew plant make using the phosphates ?

Tick () one box.

What substance can the sundew plant make using the nitrogen ?

Tick () one box.

Humans have destroyed large areas of peat bog to collect peat.

The peat provides fuel and provides compost for gardeners to use.

The peat comes from layer B in Figure 2 on page 4.

Layer B:

• contains the dead remains of plants

• has a low pH

• contains very little oxygen

• contains carbon dioxide and methane.

Figure 3 shows the removal of peat from a peat bog.

Explain how the destruction of peat bogs and the use of peat affects the temperature of the Earth’s atmosphere.

Frogs are animals that lay their eggs in water. The eggs hatch as tadpoles.

Students investigated the number of tadpoles in a pond for 8 weeks.

This is the method used.

1. Collect 10 dm³ of pond water in a bucket.

2. Count the number of tadpoles collected.

3. Put the tadpoles back into the pond.

4. Repeat steps 1 to 3 another three times in different parts of the pond.

5. Repeat steps 1 to 4 at intervals for 8 weeks.

Suggest one improvement to the method.

Table 1 shows the results.

Value X is the number of tadpoles in sample 4, at 3 weeks.

Calculate value X.

Complete Figure 4 to show how the total number of tadpoles changed over the 8 weeks.

You should:

• label the x-axis

• use a suitable scale for the x-axis

• plot the data for the total numbers of tadpoles from Table 1

• draw a line of best fit.

After 0 weeks, no more tadpoles hatched in the pond.

Calculate the percentage of the tadpoles that would still be found in the pond at 4 weeks compared with 0 weeks.

Use information from Figure 4.

After 4 weeks many of the tadpoles had died.

Suggest two reasons why the tadpoles died.

A student investigated the effect of gravity on the growth of bean seedlings.

The student put ink marks on the root of each bean seedling.

Figure 5 shows a bean seedling with ink marks.

The student set up apparatus A and apparatus B.

Figure 6 shows both sets of apparatus.

The student left both sets of apparatus in a dark cupboard for 24 hours.

Give the reason why the student placed both sets of apparatus in the dark.

What are two reasons for surrounding the seedlings with damp blotting paper?

Tick () two boxes.

Apparatus B is a control.

Explain why apparatus B is needed.

Figure 7 shows one seedling from apparatus A at the start of the investigation and after 24 hours.

The drawing of the seedling after 24 hours is not complete.

Complete Figure 7 to show:

• the appearance of the root after 24 hours

• the ink marks on the root after 24 hours.

Figure 6 is repeated below.

The student left both sets of apparatus in a dark cupboard for 24 hours.

Describe how a root from apparatus B would look different from the root you drew in Question 04.4.

Auxin is a plant hormone.

Explain how auxin causes the results in apparatus A.

Farmers can use plant hormones to control the growth of plants.

Give two uses of auxin.

A farmer sprayed an apple tree with gibberellin.

Suggest two reasons why the farmer sprayed the apple tree with gibberellin.

The human body has two coordination systems:

• the nervous system

• the endocrine system.

Two students investigated human reaction time.

Student A held a metre rule above student B ’s hand.

Student A then released the metre rule and student B caught the rule as quickly as possible.

Figure 8 shows the method used.

Suggest two ways to improve the students’ method for measuring human reaction time.

Student B ’s reaction is coordinated by the nervous system.

Give two ways that coordination by the endocrine system is different from coordination by the nervous system.

Figure 9 shows endocrine glands in a female.

Name one hormone produced by gland A.

Name one hormone produced by gland B.

The adrenal gland produces the hormone adrenaline.

Describe two effects of adrenaline on the human body.

Hormones can be used for controlling human reproduction.

Explain the use of hormones in:

• contraception

• the treatment of infertility.

Some human disorders are inherited.

Polydactyly is an inherited disorder.

• A person with polydactyly has extra fingers or toes.

• Polydactyly is caused by a dominant allele.

What is a dominant allele?

Figure 10 shows the inheritance of polydactyly in one family.

In questions 06.2 and 06.3, use the following symbols: D = allele for having polydactyly d = allele for not having polydactyly.

Person 1 is heterozygous.

Explain how Figure 10 shows that person 1 is heterozygous.

Persons 6 and 7 are expecting a fourth child.

A doctor states that the probability of having a child with polydactyly is 0.5

Explain how the doctor determined this probability.

You should:

• draw a Punnett square diagram

• give the genotype of person 6 and the genotype of person 7

• identify all the offspring that will have polydactyly.

Cystic fibrosis (CF) is another inherited disorder caused by a mutation.

The mutation occurs in a gene called CFTR.

For the CFTR gene, one allele in every 50 in the UK population is the cystic fibrosis allele.

Explain why only one person in 2500 in the UK population has cystic fibrosis.

Farmers can increase the growth rate of farm animals by controlling the animals’ diets.

A farmer has 1000 chickens.

• The farmer feeds the chickens on seeds from maize plants.

• 1 hectare of land produces 16.4 tonnes of maize seeds.

• The maize seeds have an energy content of 16 MJ per kg.

• Chickens can use 80% of the energy in maize seeds.

• Each chicken needs 46 MJ of energy to grow to full size.

Calculate the area of land needed to provide enough energy from maize seeds for 1000 chickens to grow to full size.

Give your answer in m².

Give your answer to 3 significant figures.

1 tonne = 1000 kg

Another farmer produced 4200 kg of maize seeds in a field.

The farmer fed the maize to 1000 chickens.

At full size, the mean mass of one chicken was 2.2 kg.

Complete Figure 11 to show a pyramid of biomass for the food chain from the maize seeds to 1000 chickens.

You should:

• label the x-axis

• use a suitable scale.

Calculate the ratio of chicken biomass to maize seed biomass.

Use data from Question 07.2.

Give your answer in its simplest form.

Chickens can use 80% of the biomass from the maize seeds they eat for respiration and growth.

What happens to the remaining 20% of the biomass in the maize seeds?

Protein is an important part of a chicken’s diet.

• Proteins contain 20 different types of amino acid.

• A chicken can make many of the 20 amino acids from other substances in the diet.

• Essential amino acids are amino acids the chicken cannot make.

• Essential amino acids must be included in the diet.

Maize seeds contain protein but the proportion of some essential amino acids is low.

Scientists have produced a type of maize called Quality Protein Maize (QPM).

Table 2 compares the proportions of seven essential amino acids in normal maize seeds and in QPM seeds.

Which amino acids are found in significantly higher proportions in the QPM seeds?

Tick () one box.

Table 2 shows that 1 kg of QPM contains less leucine than 1 kg of normal maize.

Suggest why a diet containing less leucine does not slow down the growth of chickens.

Conditions inside and outside of the human body often change.

Homeostasis helps the human body to survive changing conditions.

Explain what is meant by the term ‘homeostasis’.

The kidneys have an important role in homeostasis.

Describe what happens to glucose, protein and urea in the kidneys.

Explain how ADH affects the production and concentration of urine by the kidneys.

Glyphosate is a herbicide used in agriculture.

Soya bean plants have been genetically modified (GM) to be resistant to glyphosate.

A farmer can increase the yield of soya beans by:

• growing GM soya bean plants

• spraying glyphosate on the field.

Explain how the use of GM soya bean plants and glyphosate can increase the yield of soya beans.

Suggest two reasons why some people are concerned about the use of GM soya bean plants.

Do not refer to ethical concerns or religion in your answer.