OCR GCSE Combined Science B (21st Century) Paper 4 June 2023 question paper

Pathogens can cause diseases in humans.

Draw lines to connect each defence mechanism with the explanation of how it functions.

Defence mechanism
Explanation

The plant genome is inside the nucleus of each cell.

What is a genome?

What is the function of the nucleus in a plant cell?

Tick (✓) one box.

Plants make small organic molecules including sugars, fatty acids, glycerol and amino acids.

Why is it important for plants to be able to make their own amino acids?

Scientists can genetically engineer crop plants.

Complete the description of genetic engineering.

Use words from the list.

copied DNA modified protein removed desirable

Genetic engineering is a process in which the genome is........ so the crop

plant has........ characteristics.

The bar chart shows the area of land used to grow four different crop plants. Some of each crop plant grown is genetically engineered.

Give three conclusions that can be made from the data.

There are 31 million hectares of canola grown.

30% of the canola grown is genetically engineered.

Calculate the number of hectares used to grow genetically engineered canola.

Number of hectares =........ million hectares

Which two factors will the student need to control to make the student’s investigation valid?

Tick (✓) two boxes.

The student sets up a second experiment using the equipment in Fig. 3.2.

Explain how this second experiment will improve the quality of the data collected to measure the rate of photosynthesis.

The table shows the results of the second experiment.

Plot the results from the table on the graph.

Include a line of best fit.

Calculate the rate of photosynthesis.

Give your answer to 1 decimal place.

Rate of photosynthesis =........ cm³ / minute

The temperature of the water used in this experiment was 20 °C.

The student repeats the experiment at 30 °C.

What would you expect the gradient of the graph to look like at 30 °C? You may draw a labelled line on the graph.

Explain your answer.

Fig. 4.1 shows the relationship between the percentage of population with access to potable water and the number of deaths per 1000 people in the population.

Each point on Fig. 4.1 represents a country.

Percentage of population with access to potable water (%)

Explain your answer to (a)(i).

* Fig. 4.2 shows the number of deaths per 100 000 people due to typhoid fever from 1900 to 1960 in the USA.

Typhoid fever is a bacterial infection. It can be spread by drinking water that has not been treated.

Give arguments for and against chlorine being added to drinking water all over the world.

Use information from Fig. 4.1 and Fig. 4.2.

Dev reacts calcium carbonate with dilute hydrochloric acid.

The diagram shows the experiment he sets up.

Which gas is produced in this reaction?

Tick (✓) one box.

When calcium carbonate reacts with hydrochloric acid, calcium chloride is formed.

Calculate the relative formula mass of calcium chloride (CaCl₂).

Use the Data and Equation Sheet.

The graph shows how the mass of the conical flask changes during the reaction.

Explain why the mass of the conical flask decreases during the reaction.

Estimate when all of the calcium carbonate has reacted.

Explain your answer.

Explain how Dev can develop his experiment to show that mass is conserved during the reaction.

Pubmed is a search engine that can be used to search for scientific articles.

The graph shows some data about the number of articles where nanoparticles were used in medical imaging.

What can you conclude from the data in the graph?

A group of scientists studied one person who worked for a nanotechnology company. The person worked with nanochemicals and became ill.

The group of scientists concluded that “nanochemicals are bad for people’s health because they can make you ill”.

Suggest two reasons why scientists in the nanotechnology company might disagree with this conclusion.

Describe what the group of scientists should have done to improve their study.

Nanoparticles have been used in medicine alongside MRI scans to help detect cancer in patients.

Why are health professionals and patients happy to be part of nanoparticle trials?

Complete the sentence to explain how the behaviour of a magnetic compass provides evidence that the core of the Earth is magnetic.

The north pole of a magnetic compass will point towards / away from the

magnetic / geographic north pole.

Fig. 7.1 shows the Earth’s magnetic field.

How does Fig. 7.1 show that the magnetic field is strongest at the Earth’s north and south poles?

Tick (✓) one box.

Fig. 7.2 shows the poles of a permanent steel magnet and an induced iron magnet interacting with another, stronger magnet.

Explain what happens to the iron and steel magnets after the stronger magnet is removed.

When there is an electric current in a wire there is a magnetic field around the wire.

A solenoid is a coil of wire.

The table describes 4 magnets.

Explain which magnet will have the strongest magnetic field.

Two students are doing an experiment to investigate reaction times. The diagram shows their experiment.

The statements outline the method used. They are not in the correct order.

A The tester lets go of the ruler.

C The distance the ruler has dropped is measured.

D The participant has their fingers and thumb near, but not touching, the ruler.

E The tester holds a ruler above the participant’s hand.

Write the letters in the boxes to show the correct order of the statements.

The first one has been done for you.

Suggest two improvements to the method that would ensure that the measurements taken were valid.

The experiment is repeated three times. Table 8.1 shows the results.

Table 8.1

The students conduct a fourth repeat. The distance recorded is 12.7 cm.

Suggest one reason why this value of 12.7 cm is greater than the first three repeats.

The students find some data they can use to convert the distance fallen by the ruler into a reaction time. This information is in Table 8.2.

Table 8.2

A second participant repeats the experiment. The mean distance the ruler falls is 6.7 cm.

Use Table 8.2 to estimate their reaction time.

Another way of determining the reaction time is to use a formula.

Calculate the reaction time when the ruler falls 0.0670 m.

Use the formula:

t = reaction time (s) d = distance travelled by ruler (m) g = 10 N / kg.

Give your answer to 3 significant figures.

A student sets up a circuit to determine the resistance of a wire.

Complete the circuit diagram by:

• adding a cell

• adding the equipment needed to measure the potential difference and current.

The length of the wire used in the experiment is 90 cm. The current is 0.16 A and the potential difference is 1.5 V.

Calculate the resistance of the wire.

Use the equation: potential difference = current resistance

The student predicts that the longer the wire is the greater the resistance will be.

Describe how the student can extend their investigation to test their prediction.