OCR GCSE Combined Science B (21st Century) Paper 8 June 2019 question paper

Oil tankers transport crude oil. Crude oil is a mixture of hydrocarbons.

Occasionally they may be involved in an accident and catch fire as shown.

Explain why the burning hydrocarbons in the oil produce thick black smoke.

The hydrocarbon fractions in crude oil are separated by fractional distillation.

Complete the sentences about fractional distillation.

Use the words from the list. Each word can be used once, more than once, or not at all.

dissolved cooled crystallise

evaporate heated melt

During fractional distillation the mixture is heated and the fractions........

at different temperatures.

The separated fractions are then........ so that they condense.

The hydrocarbons in crude oil are mostly alkanes.

Octane is an alkane. Its molecular formula is C₈H₁₈.

Determine the empirical formula of octane.

Some ships carry condensate oil, rather than crude oil.

Give two similarities and two differences between crude oil and condensate oil.

Use Fig. 1.1 to support your answers.

Similarity 1

Similarity 2

Difference 1

Difference 2

The table shows some other differences between crude oil and condensate oil.

Which statement best explains why there is a range of temperatures for the boiling point of crude oil and condensate oil?

Tick (✓) one box.

Some people conclude that condensate oil is more dangerous to carry than crude oil.

Evaluate this conclusion.

Use the data in the table to support your answer.

Scientists have used gene technology to transfer the anthocyanin gene into tomatoes to produce blue tomatoes.

Anthocyanin is the gene for the blue pigment in blackberries.

The first stage of the gene transfer process is to locate and isolate the gene for anthocyanin in the nucleus of the blackberry cell.

Describe the next four stages in the genetic engineering process to produce blue tomatoes.

Anthocyanins are antioxidants which may prevent cell damage. This means eating blue tomatoes may be beneficial to our health.

Suggest two possible benefits of using genetically modified (GM) crops.

Blue tomatoes are still being tested and are not yet available for sale.

Suggest two possible risks of using genetically modified (GM) crops.

There are two pigments in red tomatoes, lycopene and beta-carotene. They are both soluble in water.

Chromatography can be used to determine if lycopene and beta carotene are present in blue tomatoes.

Fig. 2.1 shows a chromatogram that compares the pigments in a red tomato extract and a blue tomato extract.

Outline the method to produce the chromatogram in Fig. 2.1.

What do the results in Fig. 2.1 show?

Calculate the Rf of anthocyanin, using Fig. 2.1.

Give your answer to 2 significant figures.

Suggest two ways in which Nina and Kareem’s plan for this investigation could be improved to ensure they collect valid data.

Suggest why there is no blockage of UV for SPF 0 sunscreen.

The manufacturer claims SPF 10 sunscreen blocks out at least 95% of UV radiation.

Nina and Kareem’s investigation gives a different value for the percentage of UV blocked.

Suggest two reasons why the value from Nina and Kareem’s investigation is different.

Kareem plotted a graph of sun protection factor (SPF) against mean UV intensity.

Kareem’s teacher identifies three errors in Kareem’s graph.

Identify these three errors.

Kareem reads the labels on the bottles of SPF 30 and SPF 50 sunscreens (sun creams).

Nina says her skin usually gets burnt after 5 minutes in the sun.

Nina cannot decide whether she should use SPF 30 or SPF 50 sunscreen.

Calculate how much longer Nina could remain in the sun without being burnt if she uses SPF 50 sunscreen rather than SPF 30 sunscreen.

Give your answer in hours and minutes.

Number of hours and minutes longer = ………….……hour(s)……………minutes

Nina thinks that either sunscreen (sun cream), if used correctly, will prevent her skin from burning.

Is Nina correct?

Use your answer from (c)(i) and the information in Fig. 3.2 to justify your decision.

Give one benefit or use of UV radiation.

Galagos, or bush babies, are mammals which live in tropical forests.

Amaya and Kai see a galago (Fig. 4.1) at their local zoo.

Kai says that galagos regulate their body temperature by a process called homeostasis.

Explain why it is important that a galago maintains a body temperature of around 37 °C.

The galago lives in a heated enclosure, making it easier for it to regulate its body temperature. An electric heater keeps the enclosure warmer than the outside.

Answer the questions below.

Use words from the list. Each word can be used once, more than once, or not at all.

absorption cooling dissipation

evaporation insulation radiation

Which word best describes how the heater warms the enclosure?

Which word best describes the galago’s fur reducing its heat loss?

Which words best describe how energy is transferred from the galago, as heat, to the surroundings?

Shivering is a response to being cold.

Use Fig. 4.2 to suggest when and why the galago is most likely to shiver.

The galago enclosure is heated by a 3000 W electric heater for 12 hours every day.

Calculate the energy transferred to heat the galago enclosure for 7 days.

HIV is an infection caused by a virus. People with this virus are HIV+. HIV weakens the immune system.

Tuberculosis (TB) is a disease caused by bacteria. It may be fatal in people with a weak immune system.

The table shows information on cases of TB and HIV for three African countries.

Calculate the estimated TB cases per 100,000 for Zambia.

Give your answer to 1 decimal place.

The data shows a weak positive correlation between the percentage of TB cases that are also HIV+, and the mortality (death) rate due to TB, in the three countries investigated.

Suggest three ways the investigation could be improved, to see if a stronger correlation exists.

The death rate due to TB increased when people were HIV+.

Which two statements could explain this?

Tick (✓) two boxes.

* Jack has decided to buy House B.

Use the information in Fig. 6.1 and Fig. 6.2 to evaluate whether Jack has made the right decision.

Eve has a house and is thinking about replacing the gas boiler.

Her current boiler uses 18 000 kWh per year and her gas bill is £900 a year.

She is considering buying one of three boilers, A, B or C.

Suggest which boiler Eve should buy, and give reasons for your choice.