OCR GCSE Combined Science B (21st Century) Paper 8 November 2021 question paper

Beth plans an investigation to help her estimate the population of buttercup plants in her garden.

This is part of Beth’s method:

1. Divide the garden into four equal sections.

2. Count the number of buttercup plants in the section that has the most buttercup plants.

3. Multiply the number of buttercup plants counted by four.

Describe how Beth could improve her method.

Beth thinks three factors are having an effect on the growth of buttercup plants in her garden.

Draw lines to connect each factor with the correct explanation of its effect on buttercup plants.

Factor
Explanation of its effect on buttercup plants

A group of students plot the estimated number of buttercup plants in their gardens.

The graph shows the students’ results.

How many gardens are sampled to produce the graph?

Kai estimates that he has 450 buttercup plants in his garden.

Which percentile of the students’ data does Kai’s estimation lie below?

25^th 50^th 75^th

Sea water is a solution of salts in water.

James has three sets of equipment. They are shown in Fig. 2.1.

Explain which set of equipment James should use to separate and collect water from sea water.

Include in your answer why the other sets of equipment are unsuitable.

Crude oil is a mixture of hydrocarbons. The mixture can be separated into fractions.

The table shows the number of carbon atoms in the hydrocarbon chains of three fractions of crude oil.

Fractional distillation is used to separate the different fractions of crude oil.

Explain why naphtha is collected above fuel oil in the fractionating tower.

Complete the sentences about typical speeds.

The typical speed for walking is 0.5 m / s / 1.5 m / s / 8 m / s.

The typical speed for cycling is 7 m / s / 20 m / s / 35 m / s.

The typical speed for a car is 9 km / h / 90 km / h / 150 km / h.

Sarah cycles 20 km to work each day.

It takes her 49 minutes and 45 seconds to get to work.

Calculate Sarah’s average speed, in m / s.

Average speed =........ m / s

Sarah and her bike have a combined mass of 60 kg.

Calculate Sarah’s momentum when she is cycling downhill at 12 m / s.

Momentum =........ kg m / s

Large decelerations when cycling can be dangerous. Sarah decides to wear a bike helmet.

Complete each sentence about how a bike helmet can reduce head injuries in a collision.

Use the words.

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

decreases distance duration force increases mass speed

The cycle helmet........ the........ of the impact.

This reduces the........ on the cyclist’s head and helps to prevent head injuries.

Sarah is using the equipment in the diagram to investigate how the speed of a trolley is affected by the gradient of the ramp.

She measures the time it takes for the trolley to travel a certain distance, using a stopwatch.

How can Sarah improve her investigation to get more accurate and precise values for the speed down the ramp?

Give two conclusions that can be made from the data in the table.

Suggest what scientists should do to ensure that any conclusion they make is representative of the whole population of a country.

Calculate the percentage change in mean blood cholesterol level for men between 1960–1962 and 2007–2010.

Give your answer to 2 significant figures.

Give two conclusions that can be made from the data shown in the graph.

Suggest one way in which an individual could lower their risk of developing cardiovascular disease.

Group 1 elements react with Group 7 elements.

Complete the sentences to explain how the reaction between potassium and bromine is related to their electron arrangements.

Use the words and numbers.

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

–1 –2 +1 +2 atom electron ions

isotopes neutron one proton two

Potassium loses one........ from the outer shell of its atoms to form

........ with a charge of........ Bromine gains one

........ to fill the outer shell of its atoms to form........ with a charge of

........

Give one property of Group 1 elements and one property of Group 7 elements.

Property of Group 1 elements........

Property of Group 7 elements........

Describe how Ling can use the equipment in the diagram to produce accurate results.

When a 0.02 kg mass is attached to the spring, the spring extends by 50 mm.

Calculate the spring constant.

Use the equation: weight = mass × gravitational field strength

Gravitational field strength = 10 N / kg.

Give your answer in N / m.

Spring constant =........ N / m

When a 20 g mass is removed, the spring returns to its original length.

Suggest why the spring does not return to its original length when a mass of 30 g is used.

7* Beth is looking at a life-cycle assessment diagram for a plastic bottle made from the polymer HDPE.

The energy used in the life-cycle of one plastic bottle is shown in the diagram.

Explain the factors that should be considered when deciding if plastic bottles should be made from raw materials or from recycled pellets.

Use calculations to support your answer.

Amaya is investigating the effect of light intensity on the rate of photosynthesis in pondweed.

She uses the equipment in Fig. 8.1.

Identify two control variables that are needed to ensure Amaya collects valid data.

Describe how to change the independent variable in Amaya’s investigation.

Complete the sentence to explain why the rate of photosynthesis changes when the distance from the light source changes.

Use the words.

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

directly distance speed inversely root square sum

Light intensity is........ proportional to the........ of the

........ from the light source.

In a second experiment Amaya investigates the effect of carbon dioxide concentration on the rate of photosynthesis.

Amaya’s results are shown in the table.

PPM = parts per million

Explain the pattern shown in the data for a carbon dioxide concentration of over 600 ppm.

Fig. 8.2 shows observations that scientists have made of global temperature change over time.

The natural factors band in Fig. 8.2 shows the estimated contribution of natural factors to global temperature change over time. The size of the band represents uncertainty in the scientists’ estimates.

Give two conclusions that can be made about global temperature change over time.

Suggest what Fig. 8.2 shows about the role of humans in global temperature change over time.