OCR GCSE Combined Science B (21st Century) Paper 8 June 2022 question paper

Sundip observed her teacher reacting five different metals with water and dilute hydrochloric acid.

Suggest one safety precaution the teacher should have taken when demonstrating these reactions.

The table shows Sundip’s observations.

Write the letters of the metals in the boxes to show the correct order of reactivity.

The first one has been done for you.

Sundip predicts that the bubbles given off by these reactions are hydrogen.

To test for this she blows out a splint and places it at the top of the test tube used for each reaction.

Will this test show whether the gas is hydrogen? Explain your answer.

Sodium (Na) is a metal that reacts vigorously with hydrochloric acid (HC l) to give off hydrogen (H₂).

Complete the balanced symbol equation for the reaction of sodium with hydrochloric acid.

How many organisms are there in the longest food chain in the food web diagram?

A disease reduced the number of caterpillars in the garden. What could happen to the number of snails in the garden? Explain your answer.

Number of snails........

Explanation........

One food chain from the garden food web is

On average the transfer of biomass between organisms is 10% efficient.

The biomass of grass in the vole’s food chain is 37.5 kg.

Calculate the expected biomass of voles in the food chain.

James is looking at cells taken from the root tips of broad beans under a light microscope.

The cells are shown in the image.

James counts 76 cells in the image.

Calculate the percentage of cells undergoing mitosis in James’ image.

Suggest why James is looking at the cells in the root tips of the broad bean roots.

Mitosis is the process of producing new cells so the broad bean plant can grow.

Draw one line from each word to its correct description about mitosis and growth.

Meiosis is another form of cell division.

Complete the sentences to explain the role of meiosis.

Use the words and numbers.

You can use each word and each number once, more than once or not at all.

cells gametes genes nucleus 23

once tissues twice 46

Meiosis is a process where the cells divide........

The cells produced are called........ In humans these cells have

........ chromosomes in preparation for fertilisation.

4* The picture shows a goods lorry.

When the lorry is empty, it has a mass of 1.45 × 10⁴ kg.

The lorry can carry a maximum load of 2.95 × 10⁴ kg.

The lorry is travelling at a velocity of 25 m / s on a motorway.

Explain why the stopping distance of the lorry is different when the lorry is empty compared to when it is fully loaded.

Include calculations in your answer.

Use the equation

momentum (kg m / s) = mass (kg) × velocity (m / s)

and ideas about change in momentum in your answer.

Draw lines to connect each electrical component to its correct symbol.

Sarah is planning to make a series circuit to investigate the effect of changing the temperature of a thermistor on the current and potential difference in the circuit.

The diagram shows the circuit Sarah plans to use.

Describe two improvements she needs to make to the circuit to get valid results.

Sarah’s results at a constant room temperature can be seen in the table.

(iii) Plot Sarah’s results from the table and draw a line of best fit. The first two have been plotted for you.

Sarah repeated the experiment at different temperatures. She heated the thermistor in a water bath to increase the temperature.

Which of these graphs shows how the resistance of the thermistor changes as the temperature increases?

Tick (✓) one box.

Amir is planning an electrolysis investigation.

Amir uses a sodium chloride solution and wants to collect the gases given off at the electrodes. The diagram shows the equipment he plans to use.

Give two improvements Amir could make to his equipment.

Name the gas formed at each electrode during the electrolysis of sodium chloride solution.

Anode........

Cathode........

Scientists have discovered that breast cancer can be inherited. They have identified two alleles that can increase the risk of developing breast cancer. These two alleles are BRCA1 and BRCA2.

The table shows results from studies of women in five different countries looking at the link between BRCA alleles and breast cancer.

There were 1212 women in the Australian study.

Calculate the number of women with BRCA alleles in the Australian study who developed breast cancer.

Use the data in the table.

Which country has the highest proportion of women with cancer in the study?

A student looks at the data and draws the conclusion that roughly the same percentage of women have the BRCA1 allele as those who have the BRCA2 allele.

Explain why the student is not correct.

Genetic testing can be used to determine if someone has inherited BRCA alleles.

Suggest two ways that genetic testing for BRCA alleles can be used to reduce the incidence of breast cancer.

Some students are talking about genetic testing.

Which student is discussing the reliability of genetic testing?

Which student is talking about a medical risk of genetic testing?

The table shows some information about four nanoparticles.

Gold nanoparticles can be assumed to be spheres.

Calculate the surface area of a gold nanoparticle.

Use information from the table and the equation:

surface area of a sphere = 4r²

Use = 3.14

Give the correct unit for your answer.

Explain why silver oxide nanoparticles make an effective catalyst.

Use information from the table to support your answer.

Suggest why titanium dioxide nanoparticles might be a risk to marine ecosystems. Use information from the table and your own knowledge to support your answer.

The table gives some information about three radioactive isotopes.

Complete the nuclear equation for the decay of the uranium isotope into an isotope of thorium (Th).

A woolly mammoth was discovered in a melting glacier.

The net decline of¹⁴₆C emission of the mammoth was recorded as 1/4.

Calculate how long ago the woolly mammoth died.

Use information from the table.

Suggest one reason why the value calculated in (b)(i) is likely to be inaccurate.