Combined Science A (Gateway) · OCR J250 · Biology Paper 8 · Higher · June 2024
Gardeners are changing the way they care for their garden.
Which change would increase biodiversity?
A Adding chemical fertilisers to a grass lawn
B Cutting a grass lawn more often than usual
C Removing a grass lawn area and putting down paving stones
D Replacing a grass lawn area with a wild flower meadow
[1]
Which statement describes a difference between red blood cells and white blood cells?
A Red blood cells contain enzymes.
B Red blood cells make antibodies.
C White blood cells contain proteins.
D White blood cells respond to antigens.
[1]
Which disease may develop due to an interaction with HPV?
A AIDS
B Cervical cancer
C Tuberculosis
D Type 2 diabetes
[1]
Why does a plant scientist use antibodies specific to a type of antigen?
A To develop new plants using selective breeding
B To find new species of plants growing around the world
C To identify communicable diseases in plants
D To study the evolution of plants
[1]
Which row shows the correct order of some processes in the water cycle?
[1]
The diagram shows a phylogenetic tree for a group of related animals.
Which statement is correct?
A Aardwolf is not related to the striped hyena.
B Animal X is a common ancestor to all the hyenas.
C Brown hyena and striped hyena are the same species.
D The closest relation to the striped hyena is the spotted hyena.
[1]
Which row shows how a high cholesterol diet is linked to cardiovascular disease?
| Coronary vessel blocked by cholesterol | Gas unable to be transported to cardiac muscle, damaging the heart | |
| A | artery | carbon dioxide |
| B | artery | oxygen |
| C | vein | carbon dioxide |
| D | vein | oxygen |
[1]
To function correctly, the brain needs to make a chemical called dopamine. Parkinson’s disease is where the brain does not make enough dopamine. Embryonic stem cells might be used to treat Parkinson’s disease.
What is an ethical consideration in this kind of treatment?
A The embryonic stem cells are obtained from a human fetus.
B The embryonic stem cells may not produce the correct type of dopamine.
C The embryonic stem cells may be rejected by the patient’s immune system.
D The embryonic stem cells will not have the same genome as the patient.
[1]
Scientists are concerned that increased pollution in a forest is affecting the population of insects living in the forest.
In an investigation, scientists estimated the population of flying insects in a forest.
• They trap the insects using nets.
• The mass of insects collected each month is then recorded. The data is collected in two different years, 1995 and 2015.
The table shows their results.
| Month | Mass of insects trapped (g) | |
| 1995 | 2015 | |
| May | 450 | 50 |
| June | 520 | 120 |
| July | 920 | 160 |
| August | 420 | 110 |
| September | 100 | 20 |
Complete the bar chart to show the mass of insects collected each year. Both years should be included on the same grid. Include a Key to identify which year the bars represent.
[4]
What two conclusions can be made about the mass of flying insects in 1995 compared to 2015?
[2]
How can the scientists’ method be developed to investigate biodiversity in the forest?
[1]
In a separate investigation, scientists estimated the population of insects that live on the forest ground.
The scientists trap insects using a pitfall trap. This is a hole in the ground that the insects fall into when they crawl along the ground.
For each estimate they use this method:
• Place pitfall traps in different areas of the forest.
• Count the total number of insects caught in the pitfall traps.
• Mark the insects.
• Release the insects where they are collected from.
A week later they trap a second sample of insects.
The scientists used an ink that is not easily washed off to mark the insects for identification.
State one other precaution that they should take when deciding how to mark the insects.
[1]
They complete their investigation during July 1995 and July 2015. This table shows the results of this investigation.
| Year | Number of insects in first sample | Total number of insects in second sample | Number of marked insects in second sample |
| 1995 | 114 | 60 | 8 |
| 2015 | 146 | 63 | 6 |
The scientists use this formula to estimate the population of insects living on the forest ground:
The population of insects in 1995 is estimated to be 855.
Use the formula to estimate the population size of insects in 2015. Give your answer to 3 significant figures.
[2]
The aim of each investigation is to see if increased pollution has affected the insect population.
The population of insects living on the forest ground increased between 1995 and 2015.
Which statements about the two investigations are true, and which are false ?
Tick (✓) one box in each row.
[2]
Genetic material is required for inheritance in eukaryotic and prokaryotic cells.
Compare the genetic material found in eukaryotic and prokaryotic cells.
[2]
Peas develop inside pods.
Pea pods are either green or yellow. The allele for green is dominant over the allele for yellow.
The table shows some information about three different pea pods.
Complete the table.
| Phenotype | Genotype | Description of genotype |
| yellow | gg | homozygous ......................................... |
| green | GG | homozygous dominant |
| ............................ | Gg | ......................................... |
[2]
A gardener crosses a plant that has green pods with a plant that has yellow pods. The gardener thinks both these plants have a homozygous genotype.
The result is 15 new plants with green pods and 3 plants with yellow pods.
Show that the gardener’s green plant did not have a homozygous genotype by completing the two genetic diagrams.
Use letters G and g for the alleles.
If the green plant has a homozygous genotype:
If the green plant does not have a homozygous genotype:
[3]
The ratio the gardener achieved was 5 green to 1 yellow.
Suggest why this does not match either of the offspring ratios.
[1]
The picture shows the plant pathogen that causes powdery mildew.
Describe how powdery mildew is spread from one plant to another.
[2]
Powdery mildew reduces the efficiency of chloroplasts.
Explain how this might reduce the rate of respiration in a plant.
[3]
Plants resistant to powdery mildew are developed by genetic engineering.
Complete the sentences about genetic engineering.
The gene for resistance is cut out of DNA using a........ enzyme.
The gene is then joined to bacterial DNA using a........ enzyme.
To find out if the bacteria contain the gene, scientists use........
[3]
Explain why the process of cutting the DNA is prevented by high temperatures.
Use your knowledge of enzymes.
[2]
Powdery mildew can be controlled using chemicals.
Producing plants resistant to powdery mildew is better for biodiversity compared to using chemicals.
Suggest two reasons why.
[2]
The moisture content in soil affects the growth of plants.
Two students investigate the moisture content of different soils.
This is the method used by student X:
• Measure the mass of each soil sample.
• Place the soil samples in a warm oven to dry for 4 hours.
• Measure the mass of each soil sample again.
The table shows their results.
| Soil sample | Mass of soil sample at start (g) | Mass of soil sample after drying (g) | Percentage change in mass of soil sample (%) |
| A | 120.1 | 97.3 | 19.0 |
| B | 154.2 | 125.5 | 18.6 |
| C | 126.3 | 121.3 | ................... |
Calculate the percentage change in mass of soil sample C.
Give your answer to 3 significant figures. Write your answer in the table.
[3]
Soil sample A lost less mass than soil sample B.
Why is the percentage change in mass greater for soil sample A ?
[1]
The two students compare their results.
• Student Y used a similar method but left the soil in the oven for a different length of time.
• Student Y found the moisture content of soil sample C to be much higher than student X.
Explain why student Y found the moisture content of soil sample C to be higher than student X
[2]
What could both students do to check that the moisture content they measured is accurate?
[1]
Moisture content is one factor that affects plants.
The amount of microorganisms in the soil can also affect plant growth.
Explain why soil microorganisms are important for plant growth.
[3]
Why are microorganisms described as a biotic factor and soil moisture as an abiotic factor?
[1]
Dodo
The dodo lived in the forests on the island of Mauritius.
They evolved from a much smaller pigeon that flew to the island.
Pigeons escape predators by flying away; they nest in trees so predators find it harder to eat their eggs.
There were originally no predators or humans on Mauritius.
Dodos nested on the ground and did not fly.
Humans arrived on the island in 1598. They brought with them animals that spread across the island destroying forests and eating eggs.
The dodo became extinct by 1700.
Pigeon similar to ancestor of dodo
Dodo
* Explain how the dodo evolved to become a flightless bird and how the arrival of humans resulted in its extinction.
[6]
Suggest one way scientists could find evidence that the pigeon and the dodo have a common ancestor.
[1]
The paper as printed
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