OCR GCSE Biology B (21st Century) Depth in Biology Higher June 2023 question paper J257/04

A scientist cuts a thin slice from a plant stem, as shown in Fig. 1.1.

The slice of stem contains three different tissues.

Draw lines to connect the description of each tissue with its correct name.

One has been done for you.

Statements A to E describe steps the scientist uses to look at the slide under the microscope.

They are not in the correct order.

A Place the slide on the stage.

B Look into the eyepiece lens.

C Use the coarse focus control to move the objective lens down towards the stage.

D Use the fine focus control to move the objective lens until the image is as clear as possible.

E Use the coarse focus control to move the objective lens upwards until the image is clear.

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

One has been done for you.

Suggest two ways the scientist can work safely when using the microscope.

Fig. 1.3 shows part of the slice of stem. One of the cells is dividing by mitosis.

The chromosomes in the labelled dividing cell are clearly visible and appear dark.

Describe what the scientist added to the slide to make the chromosomes clearly visible.

To get the image in Fig. 1.3 the scientist used an eyepiece lens with a magnification of 10, and an objective lens with a magnification of 40.

Describe how to calculate the total magnification.

One of the dividing cells in Fig. 1.3 has a width of 10 m.

What is 10 m to the nearest order of magnitude?

10⁰m 10¹m 10²m 10³m

In the dividing cell, a single chromosome has a width of 0.01 m.

How many orders of magnitude larger is the cell than the single chromosome?

3 30 100 1000

Plant cells in the leaf of a tree contain chloroplasts and mitochondria.

Complete the sentences about the processes that take place in chloroplasts and mitochondria.

Use words from the list.

cellular respiration meiosis photosynthesis transpiration

In the chloroplasts, glucose is made by........

The glucose is used in the mitochondria in........

The process of cellular respiration takes place continuously in plant cells.

Explain why it has to take place continuously.

Pathogens cause communicable diseases.

Complete Table 3.1 by explaining how the spread of each communicable disease can be reduced or stopped.

Table 3.1

Ash dieback and tobacco mosaic disease are communicable diseases in plants.

Complete Table 3.2 by describing these plant diseases.

Table 3.2

A farmer is growing cherry trees. The farmer notices that some of the trees have lumps on their trunks caused by crown gall disease.

The farmer counts the lumps on five trees. Table 3.3 shows the results.

Table 3.3

Calculate the mean number of lumps per tree.

There are 200 trees on the farm. 80 of the trees have crown gall disease.

Calculate the probability that any individual tree on the farm has crown gall disease.

Fig. 4.1 is a diagram of the human eye. Some of the structures of the eye have been labelled.

Draw lines to connect each structure with its correct function.

Fig. 4.2 shows four ray diagrams.

Which ray diagram explains how the lens of the eye focuses light so that we can see a nearby object?

Tick (✓) one box.

Nina has cataracts in her eyes.

Explain why Nina can only read if she uses a bright light.

Tom is shortsighted.

Complete the ray diagram in Fig. 4.3 to show why Tom cannot see a distant object clearly.

Tom tries on a pair of glasses.

Complete the ray diagram in Fig. 4.4 to show how a lens in a pair of glasses allows Tom to see the distant object clearly.

The blood transports substances around the human body.

Carbon dioxide and urea are waste products made by cells.

Describe where in the body these waste products are removed from the blood.

Carbon dioxide........

Urea........

The blood transports sugar and hormones that control the blood sugar level.

Complete the sentences to explain how hormones control blood sugar level.

Use words from the list.

ADH auxin FSH glucagon insulin

To reduce the blood sugar level when it is too high, a hormone called

........ is released.

To increase the blood sugar level when it is too low, a hormone called

........ is released.

People living with diabetes cannot control their blood sugar level properly without treatment or lifestyle changes.

Doctors hope to treat type 1 diabetes by injecting embryonic stem cells into the patient’s pancreas.

Explain how injecting embryonic stem cells into the pancreas could help to treat type 1 diabetes.

Discuss one benefit, one risk and one ethical issue with using embryonic stem cells to treat type 1 diabetes.

Benefit........

Risk........

Ethical issue........

People with type 2 diabetes have asked if they can also have the stem cell treatment.

Explain why other treatments may be better for people with type 2 diabetes.

Fungi are a type of organism that live in soil. They are eukaryotic.

Fungi use their genome to make proteins, like humans.

Describe what the fungi’s genome is and where it is stored.

Explain how the genome is used to make proteins.

Fungi release digestive enzymes into the soil.

Explain why these enzymes are helpful to organisms other than the fungi.

A scientist collects soil samples from three different sites. The soil samples contain an enzyme released by fungi.

The scientist tests the enzyme from each soil sample by:

• adding the enzyme to its substrate in 10 solutions, each with a different pH

• measuring the rate of reaction.

The scientist plans to control the temperature of the solutions by leaving them in the same room.

Describe a better way to control the temperature of each solution.

The scientist makes sure that:

• the same type of enzyme is taken from each soil sample

• the same concentration of enzyme is used in each solution

• the same substrate is used in each solution.

Describe one other factor that could affect the rate of the enzyme reaction and how this factor could be controlled.

Factor........

How it could be controlled........

The results of the tests are shown in the graphs.

What was the optimum pH for the enzyme from sample A ?

What was the maximum rate of reaction for the enzyme from sample B ?

Maximum rate of reaction =........ arbitrary units

Describe and explain the general trend in the results for the enzyme from sample B.

The scientist thinks a mutation must have happened in the fungi in the soil in sample C.

Describe how this mutation could have caused the results for sample C.

The scientist concludes that the enzyme works best in alkaline soil.

Give evidence for and against the scientist’s conclusion.

For........

Against........

Elephants live in the wild in Mozambique, Africa.

Some elephants inherit an allele that causes them to never develop tusks. This no-tusks allele is the result of a mutation.

Mutations to alleles happen quite often.

Explain why mutations often have no observable effects.

* The scientists found that the no-tusks allele was more common in each new generation of the elephants.

Explain the scientists’ finding.

Elephants have sex chromosomes just like humans.

• Female elephants have the genotype X X.

• Male elephants have the genotype X Y.

Scientists have discovered that:

• The no-tusks allele, T, is dominant.

• The allele for normal tusks, t, is recessive.

• The alleles are found on the X chromosome. This means an X chromosome can be either X^T or X^t.

• All elephants that have the genotype X^T Y die before they are born.

What is the phenotype of an elephant that has the genotype X^T X^t?

Explain why no female elephants are born homozygous for the no-tusks allele.

A female elephant that is heterozygous for the no-tusks allele has a baby.

Complete the Punnett square to show the possible genotypes of the baby.

A scientist concludes that this female elephant is likely to have twice as many female offspring as male offspring.

Explain why the scientist is correct.

Predict what is likely to happen to the population of elephants in Mozambique if the hunting continues.