OCR GCSE Combined Science B (21st Century) Paper 1 June 2023 question paper

Some bacteria are pathogens that cause diseases.

Our blood contains white blood cells. They help protect us against pathogens.

Write down the name of the organ that pumps the blood around our body.

Which system are white blood cells a part of?

Tick (✓) one box.

The human body has different types of defences against pathogens.

Draw lines to connect each type of defence with the correct example.

Type of defence
Example

Beth has a cut on her finger.

Platelets in Beth’s blood help to seal the cut so bacteria can’t get into it.

Which two statements explain how her platelets do this?

Tick (✓) two boxes.

Medicines can be used to treat diseases.

Complete the sentences to explain the use of medicines in the treatment of disease.

Use words from the list.

........ medicines kill pathogens.

........ medicines treat the symptoms of disease.

Four groups of students recorded how many times they had to take medicine in a year. There were eight students in each group.

Table 2.1 shows the results for Group 1.

Table 2.1

What is the median number of times medicine had to be taken in Group 1 ?

4 7 8 10

Table 2.2 shows the mean for each group.

Table 2.2

Complete the bar chart of the data in Table 2.2.

Make sure you:

• complete the scale on the y-axis

• plot the two missing means.

What is a correct conclusion from the data?

Tick (✓) one box.

All the students in these groups are 16 years old. They are all girls. They are a small sample of all of the 16-year-olds in the UK.

Describe two ways you could get a better estimate of the mean value for 16-year-olds in the UK without asking all of them.

Alex touches a hot flame.

Alex’s arm moves quickly away from the hot flame. This is a reflex response.

The diagram shows the reflex arc.

Statements A to E explain how the structures of the reflex arc work to move Alex’s arm.

The statements are not in the correct order.

A Heat detected by pain receptors in Alex’s skin.

B Nerve impulse travels along motor neuron.

C Muscle contracts and moves Alex’s arm away from the flame.

D Nerve impulse travels along relay neuron.

E Nerve impulse travels along sensory neuron.

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

One has been done for you.

There are many species of plants and animals on Earth.

* Charlie lives next to a forest.

Ling is a science student.

Explain advantages and disadvantages of stopping people from cutting down trees in the forest.

There are differences between the individuals within a population of a species.

This variation can be caused by the environment.

State one other cause of variation between individuals.

Darwin and Wallace suggested that new species could evolve from earlier species.

Which two statements describe how fossils provide evidence for this idea?

Tick (✓) two boxes.

Some bacteria have evolved to become resistant to antibiotics.

Which statements about antibiotic resistance are true, and which are false ?

Tick (✓) one box for each statement.

True False

Scientists can classify organisms into species based on similarities in their physical features.

Describe how DNA analysis can also be used to classify organisms into species.

The diagram shows a complete food chain.

Grass Grasshoppers Bluebirds Owls

Biomass is passed through this food chain when the organisms eat each other.

Where was all of this biomass originally produced?

The amount of biomass in the grass is 810 kg / m³. (b)

The amount of this biomass passed on to the grasshoppers is 37 kg / m³.

Calculate the percentage of the grass’s biomass passed on to the grasshoppers.

Give your answer to 3 significant figures.

Photosynthesis in the grass makes glucose. The grass uses some of this glucose to make amino acids, fatty acids, glycerol, and other sugars.

Which statements about these substances are true, and which are false ?

Tick (✓) one box for each statement.

True False

Water and other substances are transported into and out of plants.

Complete the table to describe how each substance is related to photosynthesis.

Tick (✓) the correct boxes.

Jack investigates the effect of temperature on the amount of water taken up by a plant shoot.

He uses this apparatus to measure the amount of water taken up by the shoot.

Water is taken up into the shoot to replace water that evaporates from its leaves.

When water is taken up into the shoot, the air bubble moves along the scale.

Jack does a practice attempt with the apparatus. His results are shown in the table.

Calculate how many mm of water were taken up into the shoot in this practice attempt.

At which temperature was this experiment done?

Use the graph.

Calculate the average rate at which the 20 mm of water was taken up over the 20 minutes in this experiment.

Rate =........ mm / min

Explain why water was taken up more quickly by the shoot at higher temperatures.

Bioethanol can be used as a fuel in cars.

This type of ethanol is made when anaerobic respiration happens in yeast.

A teacher uses the equipment in the diagram to make this type of ethanol.

The yeast use glucose from a plant called ‘sugar beet’ for anaerobic respiration.

After 30 minutes the mixture is bubbling and feels warmer than it did at the start.

Why does the mixture feel warmer?

The mixture feels warmer because the process of respiration is

endothermic / exothermic / photosynthetic.

Why does the mixture bubble after 30 minutes?

Another type of respiration is aerobic respiration.

Complete the table to compare the processes of aerobic and anaerobic respiration.

Tick (✓) one box in each row.

The teacher uses a light microscope to count the yeast cells in one drop of the mixture.

From this the teacher estimates there are 2 million yeast cells in the mixture in the flask.

Explain why this is only an estimate of the number of yeast cells in the flask.

Aerobic respiration happens in the mitochondria in yeast cells.

An electron microscope was used to make this image of a mitochondrion.

Length = 2 micrometers

The length of the mitochondrion in the image is 2 micrometers.

Use this information to estimate the height of the mitochondrion.

Height of mitochondrion =........ micrometers

Complete the sentences to explain how electron microscopes have increased our understanding of sub-cellular structures such as mitochondria.

An electron microscope has high magnification, which allows us to see structures that

are very dark / large / light / small.

An electron microscope has high resolution, which allows us to tell the difference

between structures that are very close together / dark / far apart / light.

Sam is learning about surface area: volume ratio.

Calculate the volume of cube B.

Calculate the surface area: volume ratio of cube C.

Surface area: volume ratio =........:........

Describe the relationship between cube size and surface area: volume ratio.

Sam places jelly cubes A, B, C and D into a solution of coloured stain. The stain diffuses into the jelly cubes.

Predict which cube will take the longest time for the stain to diffuse to the centre of the cube.

Explain your answer.

Humans are large animals. The human body is made of millions of cells.

To stay alive, every cell in the body needs a constant supply of water and other substances that are absorbed into the body by the digestive system.

Parts of the wall of the digestive system are covered with structures called villi, as shown in Fig. 8.2.

The surface area of the digestive system wall has villi rather than being flat.

Explain why this is an advantage.

The villi contain blood vessels.

Explain why this is an advantage.

Our features are affected by our genome and our environment.

Which statement is correct?

Tick (✓) one box.

Scientists have different terms for different parts of the genome.

Draw lines to connect each term with its correct explanation.

Term Explanation

A scientist says:

Explain the terms phenotype and genotype.

Describe how our genes affect our features.

Describe one example of how our features can be affected by our environment.

A doctor uses a light microscope to look at the chromosomes in human body cells.

The microscope is shown in the diagram.

Draw lines to connect each part of the microscope with its correct name.

The doctor uses steps A to D to look at the cells on a slide.

The steps are not in the correct order.

A Turn the coarse focus until the image is as clear as possible.

B Turn the fine focus until the image is as clear as possible.

C Adjust the mirror until the image is bright enough to see.

D Place the slide under the microscope.

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

One has been done for you.

The chromosomes in the cells are not clearly visible under the microscope.

Describe one thing the doctor can add to the slide to improve the visibility of the chromosomes.

Humans have X and Y sex chromosomes.

The Punnett square shows how X and Y chromosomes are inherited.

What is the probability that a fertilised egg will have the chromosomes XY?

0 0.5 1 2

What is the expected ratio of XX to XY offspring?

Describe how inheriting a Y chromosome causes the baby to be born with male characteristics.

Some females have a condition called Turner syndrome.

• They only have one X chromosome instead of two.

• There is no cure.

• They need to have their heart, kidneys and reproductive system checked regularly for problems throughout their lives.

A baby can be tested for Turner syndrome before they are born. Their chromosomes are tested using a sample of amniotic fluid from the womb.

Describe benefits and risks of doing this test before the baby is born.

Hormones help to control the human body.

A student measured their blood sugar level every 5 minutes after eating chocolate.

The results are shown in the graph.

Calculate the change in blood sugar level between 10 minutes and 25 minutes after eating the chocolate.

Change in blood sugar level =........ mg / 10 cm³

Between which times does the hormone insulin start to affect the student’s blood sugar level?

Tick (✓) one box.

The student concludes that their normal blood sugar level is 105 mg / 10 cm³. (iii)

Describe evidence from the graph that supports this conclusion.

Hormones can be used as a contraceptive.

Explain one benefit and one risk of taking a contraceptive pill containing hormones.