OCR GCSE Biology B (21st Century) Depth in Biology Foundation June 2025 question paper J257/02

Which system transports oxygen and dissolved food molecules around the human body in the blood?

Tick (✓) one box.

Which organ pumps blood around the human body?

Tick (✓) one box.

Which type of blood vessel has valves to stop blood flowing backwards?

Tick (✓) one box.

Draw lines to connect each part of the blood with its correct function.

Put these three structures in order of size, from the largest to the smallest.

Chromosome Gene Nucleotide

Largest........

Smallest........

Which statement describes the genome?

Tick (✓) one box.

Organisms can be classified based on their sub-cellular structures.

Fig. 3.1 is a diagram of a cell showing its sub-cellular structures.

Fig. 3.1

Classify the organism that the cell in Fig. 3.1 has come from.

Tick (✓) one box.

State one piece of evidence present in the nucleus of the cell in Fig. 3.1 that scientists could use to help classify the organism.

Fig. 3.2 is a diagram of a different cell.

State two reasons why the cell in Fig. 3.2 would be classified as prokaryotic and not as eukaryotic.

Plant leaves have tiny holes called stomata on their surfaces.

A student uses a light microscope to observe stomata on the underside of a small rectangular piece of a leaf.

Fig. 4.1 shows a light microscope.

Write the correct letter, A, B, C or D, next to each part.

Eyepiece lens........

Light........

Objective lens........

Stage........

Complete the method to describe how to set up the light microscope to observe stomata on a slide.

Use words from the list.

eyepiece light objective slide stage

1. Place the........ under the clips.

2. Looking from the side, turn the coarse focus to move the stage towards the

........ lens.

3. Looking into the........ lens, use the coarse and fine focus to adjust

the image until it is clear.

Why is it important to look from the side in step 2 of the method?

Fig. 4.2 shows what the student observes.

Calculate the area of the piece of leaf shown in Fig. 4.2.

Fig. 4.3 shows the underside of the leaf on a grid.

Each square of the grid measures 1 cm 1 cm.

Estimate the surface area of the underside of the leaf.

Use Fig. 4.3.

Include every square that is half-filled or more than half-filled with leaf.

Describe how the student can produce an estimate of the total number of stomata on the underside of the leaf without counting all of them.

Explain one benefit of producing an estimate of the total number of stomata on a leaf rather than counting all of them.

The student produces estimates of the total number of stomata present on the top side and underside of five leaves from the same plant.

The table shows their results.

Write one conclusion about the distribution of stomata on leaves shown by the data in the table.

Fig. 4.4 shows one of the stomata observed with a more powerful microscope.

Which part is a guard cell?

Tick (✓) one box.

Each body cell in a cat has 38 chromosomes.

Cats reproduce sexually.

The gametes are made by meiosis, starting with one of the cat’s cells.

Complete the diagram to show the number of chromosomes found in each cell during the stages of meiosis.

How many chromosomes will be present in a cat’s zygote after fertilisation?

Number of chromosomes in cat’s zygote =........ chromosomes

Adult body cells divide to make more body cells as part of the cell cycle.

Statements A to E are steps in this process. The statements are not in the correct order.

A The cell divides.

B The cell grows larger.

C The chromosomes are copied.

D The chromosome copies separate.

E The nucleus divides.

Write one letter in each box to show the correct order of the steps.

One of the steps has been done for you.

The cell cycle is divided into two parts called interphase and mitosis.

Tick (✓) two boxes to show the steps that take place during interphase.

Complete the sentence about mitosis.

Use a word from the list.

different fertilised gametes identical

The cells produced by mitosis are genetically........

Describe how cancer can sometimes result from mitosis.

Ash trees are common in the UK.

What is the role of an ash tree in a food chain?

Tick (✓) one box.

Describe two ways animals can be affected if an ash tree is removed from the ecosystem it was growing in.

Many of the UK’s ash trees are being killed by a disease called ash dieback. Ash dieback is caused by a pathogen that can spread from tree to tree.

Tick (✓) one box in each table to identify the pathogen that causes ash dieback and how it

Which two of these are used by plants as a defence against pathogens?

Tick (✓) two boxes.

A few ash trees are resistant and do not die when infected with ash dieback.

Complete the sentences to explain why resistant trees will gradually become more common.

Use words from the list.

adaptation competition mutation

natural selection
reproduction
variation

Resistant trees have a genetic variant created by........

These trees are more likely to make offspring by........

The offspring could inherit the genetic variant for resistance.

This is the process of........

* Scientists predict that ash dieback is likely to kill up to 80% of our 3 billion ash trees and cost the UK approximately £15 billion.

Scientists have discovered a species of fungus that releases a chemical that is toxic to the ash dieback pathogen.

Explain possible benefits and risks of releasing this fungus with its toxin into woodland in the UK.

Fig. 7.1 shows the percentage of women and men in the UK who were classed as severely obese each year from 2000 to 2019.

Fig. 7.1

What percentage of women were classed as severely obese in 2002?

Which three statements about the data in Fig. 7.1 are true ?

Tick (✓) three boxes.

2000 to 2002 was the only time period where the percentage of men classed as severely obese stayed the same.

The overall change in percentage of people classed as severely obese between 2000 and 2019 was bigger for women than men.

The percentages of women and men with cardiovascular disease also increased from 2000 to 2019.

Suggest how the data in Fig. 7.1 could be linked to the increase in cardiovascular disease.

Measurements of a person’s body can be used to draw conclusions about their health.

An adult has a mass of 81 kg and a height of 1.80 m

Calculate the body mass index (BMI) of the adult.

BMI =........ kg / m²

Table 7.2 shows how BMI values can be categorised.

Table 7.2

Which category is an adult with a BMI of 23.0 kg / m² in?

Some doctors think that a person’s BMI alone can be misleading. They recommend that a person’s waist-to-height ratio should also be considered.

Zayn has a waist circumference of 81 cm and a height of 179 cm.

Calculate the waist-to-height ratio for Zayn.

Give your answer to 2 decimal places.

Table 7.3 shows how waist-to-height ratios can be categorised.

Table 7.3

Amaya does very little exercise. She has a BMI of 31.6 kg / m² and her waist-to-height ratio is 0.56.

Explain:

• why Amaya is at high risk of developing type 2 diabetes

• how she can reduce her risk.

Use Table 7.2 and Table 7.3 to help you.

Alex is thinking about his health. Here are some notes about Alex.

Waist-to-height ratio: 0.43

Body type: Very muscular. Low levels of body fat.

Exercise: Running daily. Regular muscle-building at the gym.

Alex finds out that his BMI is classed as obese.

He thinks he should lose weight to lower his risk of disease.

Explain why Alex is not correct.

Use Table 7.3 and the notes on Alex to help you.

The pupil is part of the human eye.

A student investigates the effect of changing the light level on pupil diameter.

The student uses a lamp with adjustable brightness, measured in lumens. The maximum brightness of the lamp is 1200 lumens (100%).

Table 8.1 shows the data the student records.

Table 8.1

Complete Table 8.2 to identify the variables in the investigation.

Put one tick (✓) in each row to show whether the variable is the dependent variable, the independent variable or neither.

Table 8.2

Suggest one other variable not included in Table 8.2 that should be controlled.

Calculate the number of lumens equivalent to a light level of 80%.

Use the data in Table 8.1.

Number of lumens equivalent to a light level of 80% =........ lumens

The student measures the pupil diameter by holding a ruler against the person’s eye.

Suggest a safer way to measure the pupil diameter.

The student predicts that if a light brightness of 1200 lumens is tested, the pupil diameter will be approximately 2 mm.

Explain why the student is correct.

Which part of the bottle garden ecosystem is biotic ?

Tick (✓) one box.

Explain why the air in the bottle is an abiotic part of the ecosystem.

The bottle allows light to pass through it.

Explain why this is essential for the plant to survive.

* A bung is used to seal the bottle closed.

The plant stays alive even though the bottle is kept sealed for years and no extra water is added.

Explain:

• why the plant needs water

• how the plant gets enough water even though the bottle is kept sealed.