OCR GCSE Combined Science B (21st Century) Paper 8 June 2018 question paper

Parkinson’s disease is a condition that affects the nervous system. There is currently no cure for the disease.

It is estimated that 145 000 people will have Parkinson’s disease in 2018. It is predicted that by 2025 the number of people with Parkinson’s disease will rise by Calculate how many more people will have Parkinson’s disease in 2025 than in 2018.

Scientists have observed that smoking affects people’s risk of developing the disease.

The scientists investigated three groups of patients with Parkinson’s disease.

A total of 1808 patients were studied.

Discuss the findings of the study.

One hypothesis states that nicotine in cigarettes may protect against Parkinson’s disease.

People use e-cigarettes because they may be a less harmful source of nicotine.

Pure nicotine is a liquid at room temperature.

Fig. 1.1 is a simplified diagram showing how an e-cigarette works.

Describe what happens to nicotine particles in the heating chamber in an e-cigarette.

Compare the changes that occur in an e-cigarette with those in a cigarette that burns tobacco.

Which student is discussing the idea of correlation and cause?

Tick (✓) one box.

Which student has suggested a possible mechanism for the action of nicotine?

Tick (✓) one box.

* Food plants in the same family as tobacco also contain nicotine.

Scientists have studied how eating these foods affects the numbers of people with Parkinson’s disease.

People with Parkinson’s disease answered a questionnaire about their diet.

Scientists assessed the risk of developing Parkinson’s disease in people that ate plant foods containing nicotine. The results are shown in Table 1.1.

*This is the person’s risk compared with patients who ate foods containing no nicotine.

For example:

• if the risk is 2.00, you are twice as likely to get the disease

• if the risk is 0.50, you are half as likely to get the disease.

Use the information to determine if there is a correlation between eating plant foods with different concentrations of nicotine and the risk of developing Parkinson’s disease.

Use the date in Table 1.1 to support your answer.

Alex and Beth are investigating reaction time.

Alex drops a 30 cm ruler. Beth catches the ruler between her thumb and fingers as shown in Fig. 2.1.

The distance the ruler fell before being caught is recorded.

The students’ results are shown in Table 2.1.

Calculate the mean distance the ruler dropped.

The time taken to catch the ruler, and therefore the person’s reaction time, can be calculated using the following formula:

t = time in seconds d = mean distance in metres a = acceleration as a result of gravity = 9.81 m / s²

Use your answer to (a)(i). Calculate the mean reaction time in milliseconds.

Give your answer to 3 significant figures.

Receptors in the eye detect the stimulus that results in the ruler being caught.

Use your knowledge of the nervous system to describe this sequence of events.

The majority of the world’s alcohol, 93%, is produced by the traditional method of fermentation of glucose with yeast.

Nina is investigating alcohol (ethanol) production as a sample of beer is brewed.

Fermentation of glucose with yeast can be represented by an equation.

Balance the chemical equation for the reaction.

glucose → ethanol + carbon dioxide

Nina’s class investigates the rate of the reaction.

To do this, groups of students:

• measure the volume of ethanol produced over a period of time

• measure the rate of carbon dioxide production.

Suggest one other physical method for determining the rate of chemical reactions.

What conclusions can be made from the graph in Fig. 3.2 ?

Explain your answer.

Suggest how the optimum temperature could be estimated with more accuracy.

Ethanol can be made industrially from ethene.

The chemical reaction is shown below.

The reaction is carried out at 300 °C at a pressure of 6–7 MPa with a phosphoric (V) acid catalyst.

Suggest two reasons why 93% of the world’s ethanol is produced by fermentation.

PET is the main type of polymer used for manufacturing plastic drinks bottles.

Table 4.1 shows part of a Life Cycle Assessment (LCA) for PET bottles.

The LCA is from the production of PET to the sale of the bottles in supermarkets.

Which statements about the Life Cycle Assessment for PET bottles are true, and which are false ?

Put a tick (✓) in one box in each row.

Describe one of the processes used to recycle PET drinks bottles.

The PET polymer was considered non-biodegradable.

In 2016, scientists in Japan discovered a type of bacterium, normally found in the soil, living on the surface of waste PET bottles. The bacterium produces enzymes that break down the polymer.

The scientists think that the bacterium may be useful in the recycling of the plastic.

Suggest one way in which the bacterium might improve recycling.

PET was developed in 1941. PET bottles were first used in 1973.

Until 2016, no bacterium had been found that would biodegrade this plastic.

Suggest the genetic changes that occurred in this soil-living bacterium after 1973.

Explain your answer.

The decay of radioactive isotopes is important in dating archaeological and fossil objects.

An isotope of carbon, called carbon-14, is present in small amounts in all living things.

Carbon-14, or¹⁴C, is important in dating objects in archaeological studies.

Living organisms exchange carbon, including carbon-14, between themselves and the environment. When an organism dies, this carbon is no longer exchanged and the amount of carbon-14 present decreases as the organism decays.

The age of the archaeological remains of humans and other organisms can be estimated from the proportion of carbon-14 that remains undecayed.

Suggest one assumption that must be made when dating samples using carbon-14.

When potassium-40 decays, one decay product is argon-40.

Argon-40 makes up 99.6% of the argon on earth.

The half-life of potassium-40 is 1.251 × 10⁹ years.

Explain why carbon-14 can only be used to date objects up to around 50 000 years old, but potassium-40 can be used to date rocks containing fossils many millions of years old.

Some stable isotopes are used to investigate archaeological objects.

In 2012, the skeleton of King Richard III was discovered under a car park in Leicester.

Scientists analysed levels of the stable isotopes nitrogen-15 and oxygen-18 in teeth from the king’s skeleton. These isotopes do not decay and their levels remain constant.

Suggest how the¹⁵N was taken into the king’s body.

Amir is investigating the properties of types of resistor.

He sets up a circuit to measure the resistance of a thermistor at different temperatures.

Draw a suitable circuit diagram for the experiment.

The results of Amir’s experiment are shown in Table 6.1.

Complete the graph by plotting the results from Table 6.1 and draw a line of best fit. Some have been plotted for you.

Amir sets up the circuit above.

V_in = 10 V

Resistor R₂ has a value of 10 k.

Amir replaces R₁ in the circuit diagram with the thermistor he used in his experiment.

He carries out this new experiment at 15 °C.

Using the equation above, and the information from the graph, predict a value of V_out

Give your answer to 1 decimal place.

Predicted value of V_out =........ V

Using this model, what effect would increasing the temperature to 90 °C have on V_out

Calculate the current in the potential divider circuit at 60 °C.