OCR GCSE Combined Science A (Gateway) Biology Paper 8 Higher June 2018 question paper J250/08

A Environmental selection

B Genetic engineering

C Natural selection

D Selective breeding

Look at the diagram showing parts of the nitrogen cycle.

Which part of the nitrogen cycle involves bacteria as decomposers?

The diagram shows a virus.

Which structure A, B, C or D is the antigen when the virus invades a host?

If a person has one disease, it is sometimes more likely that they will develop another disease.

Which pair of diseases affects each other this way?

A HIV infection and cervical cancer

B HPV infection and cervical cancer

C HPV infection and tuberculosis

D Tuberculosis and cervical cancer

The number of deaths in the UK in 2012 was 569 024.

It is estimated that 165 818 of these were cancer-related deaths.

What percentage of the deaths in the UK in 2012 were cancer-related?

A 0.29

B 3.43

C 29.14

D 34.32

Some bacteria have evolved to become resistant to antibiotics.

Which statement is true about the evolution of these bacteria?

A Antibiotics killed the resistant bacteria.

B Bacteria reproduce slowly allowing the resistance to have affect.

C Mutations in some bacteria were an advantage.

D Mutations occurred within the nucleus of the bacteria.

Countries can compensate for their greenhouse gas emissions by planting new trees.

Why does planting new trees help compensate for their greenhouse gas emissions?

A Produces biomass

B Removes carbon dioxide from the air

C Releases oxygen into the air

D Water absorbed from the soil prevents flooding

Which statement is not true about line transects?

A They allow study of a linear habitat like a roadside verge.

B They can be used to study which species are present in a habitat.

C They give an exact measure of how many of each species is present in a habitat.

D They show how the abundance of a species changes across a particular habitat.

Testing drugs using a double blind trial improves reliability.

Why is reliability improved?

A Observer and volunteer bias is not removed.

B Observer and volunteer bias is removed.

C Volunteer bias is removed but not observer bias.

D Observer bias is removed but not volunteer bias.

Antiviral drugs can work in different ways.

Which statement shows how an antiviral drug can work?

A It acts as a vaccine against the virus.

B It causes phagocytosis of the virus.

C It contains antibiotics to destroy the virus.

D It stops the virus releasing its genetic material.

The picture shows a mealybug insect.

This mealybug is a pest for orange tree growers.

The scientists compared the number of mealybugs found on two trees, tree A and tree B.

For each tree they:

• Collected a sample of mealybugs from the tree

• Counted the number of mealybugs in each sample

• Marked the mealybugs

• Released the mealybugs back onto the tree they were collected from.

The next day another sample was collected from each tree.

Describe how the scientists should collect and mark the mealybugs.

Include the equipment they need to use.

You may include a diagram with your answer.

Write down three precautions that should be taken when deciding how to mark the mealybugs.

The table shows the results for tree A.

Estimate the population size of mealybugs on tree A.

Use the formula:

When using this method to estimate population, the scientists make several assumptions.

One assumption is that there was no immigration of mealybugs between day 1 and 2.

Suggest two other assumptions they would make.

The number of mealybugs on each tree may be affected by the light intensity.

The scientists measured the light intensity for each tree at midday on day 1 of their investigation. Light intensity is measured using a light meter.

Tree B had an estimated population of 250 mealybugs at the end of the investigation. Tree B had a higher light intensity reading than tree A.

Read this statement.

The mealybugs are thought to breed rapidly in low light conditions.

Do the results for the two trees support this statement?

Use the information above and your answer to (c)(i).

Explain your answer.

Errors can occur when taking light meter readings.

Explain how errors occur and write down one way to take more precise readings.

Cardiovascular disease (CVD) is a major cause of death in the UK.

Look at the diagram of the external features of a heart.

The coronary artery supplies the cardiac muscle with oxygen.

Label the diagram to show the position of one of the coronary arteries.

Angina is a symptom of CVD. Pain from angina is caused by cardiac muscle respiring anaerobically.

Explain why angina causes pain.

A 55 year old patient has severe chest pains due to a narrowed coronary artery.

The diagram shows the cross-section of a normal coronary artery and the patient’s artery.

Normal coronary artery
Patient’s coronary artery

The cross-sectional area of the normal coronary artery lumen is 18.1 mm².

Calculate the cross-sectional area of the lumen of the patient’s artery.

Use the equations:

Give your answer to 2 significant figures.

Calculate the percentage reduction in cross-sectional area for the lumen of the patient’s artery.

CVD can be treated by different combinations of lifestyle changes, medicine and surgery.

Look at the information on CVD and how much the coronary artery has been narrowed

Justify why the patient would need surgery.

* Doctors rely on different types of surgery to treat cardiovascular disease.

The table shows features of three surgical treatments.

Evaluate the three surgical treatments and decide which would be the best type of surgery for the 55 year old patient.

Insulin and glucagon are hormones that control blood sugar levels in the body.

The diagram shows interactions between these two hormones.

Complete the diagram to show how insulin and glucagon work together to control blood

sugar levels.

This type of control system is an example of negative feedback.

Explain why.

Type 1 diabetes is a disorder caused by lack of insulin production in the pancreas. Type 1 diabetes has a genetic link.

In humans the haploid number of chromosomes is 23. Insulin is a hormone controlled by a single gene found on chromosome number 11.

How many chromosomes are there in a single human pancreas cell?

Some individuals have a copy of the gene that would cause diabetes but do not have the disorder.

Suggest a reason why.

Some people can inherit a rare condition called ADPKD that results in kidney disease.

The PKD1 gene provides instructions for making a protein called polycystin-1. Polycystin-1 controls kidney cell differentiation.

In ADPKD, polycystin-1 does not work properly.

What name is given to a change in the PKD1 gene that causes ADPKD?

Explain why the ADPKD version of polycystin-1 prevents the kidney working properly.

A pregnant woman is heterozygous for ADPKD. The baby’s father does not have ADPKD and is homozygous recessive.

ADPKD is caused by a dominant allele (D).

What is the probability of their baby having ADPKD?

Use a labelled genetic diagram to explain your answer.

The bacteria, Agrobacterium tumefaciens, causes crown gall disease that affects walnut trees.

Galls form on the parts of the plant growing above ground (crown) or on the roots.

Describe how the galls form and cause damage to the walnut tree.

Explain one reason why the scientists thought this would happen.

To what extent does the evidence support their hypothesis?

Explain your answer.

Write down two other conclusions that can be made from the data.