The Challenges of Size (OCR Gateway GCSE Biology: Combined Science)

Fanconi anaemia is a genetic disorder. It results in the bone marrow being destroyed.
This causes a decrease in the numbers of red blood cells, white blood cells and platelets.

Explain two possible symptoms of Fanconi anaemia.

1 ...................................
2 ...................................

Table 19.1 shows normal ranges for blood components in people without Fanconi anaemia.

The diagram shows a microscope slide containing blood from a patient.

The square cover slip is 10mm wide and the thickness of the blood underneath is 0.001mm.

Calculate the volume of blood under the cover slip.

Volume of blood = ...................... mm³ [1]

[3]

There are many different genetic disorders that can affect blood cells. Details of three of these are found in Table 19.2.

A blood smear from another patient shows that he has 3 × 10⁶ red blood cells per mm³ of blood. Neither of his parents have a blood disorder.

Use Table 19.1 and Table 19.2 to explain which blood disorder the patient could have.

Name of disorder ...........................
Explanation ............................

The diagram shows a cross-section of a plant stem.

A greenfly feeds on the plant by piercing through to the tissue shown in the cross-section of a plant stem.

(i)

What is the name of the tissue in the stem that the greenfly is trying to reach with its mouthpart?

Tick (✓) one box.

[1]

 [2]

A gardener carries out an experiment using two similar tomato plants. The tomato plants are grown in pots.

She puts one inside a glasshouse and one outside beside the glasshouse.

To decide which plant loses the most water, the gardener looks to see which plant wilts first.

The diagrams show a plant before and after it has wilted.

Fifty years ago scientists experimenting on plants had to inject dyes to measure water flow.

Now they can use modern methods such as MRI and X-ray imaging.

Scientists are now developing new ideas on how water flows through a plant that are different from theories developed fifty years ago.

Explain why.

The diagram shows structures on the surface of a leaf.

An experiment was done to look at the effect of ‘ringing’ on a tree trunk. Ringing removes a strip of plant tissue from around the stem of the tree.

The diagram shows where the stem is ringed.

The results were recorded after one week.

The diagram shows the results.

What conclusions can be made about the results?

Some students investigate the effect of the surface area : volume ratio on the rate of diffusion in animal cells.

They use hydrochloric acid and gelatine cubes that have been stained blue using a pH indicator solution. The indicator will turn red in acidic conditions.

They put different sized cubes into 3 different test tubes of hydrochloric acid and time how long it takes for the cubes to completely change to red.

Fig. 16.1 shows the apparatus they use.

Fig. 16.1

The table shows the students’ results.

surface area : volume ratio = ..................... [2]

[1]

[2]

In a condition called sickle cell anaemia, the red blood cells can change shape. This reduces the amount of oxygen getting to cells in the body.

Fig. 16.2 shows a red blood cell and a sickled red blood cell.

Explain why sickle cell anaemia reduces the amount of oxygen getting to cells in the body.

The diagram shows a simple potometer.

The apparatus can be used to investigate the effect of light intensity on transpiration rates.

[2]

[3]

[2]

The table shows the results from using the potometer.

(i)

The mean distance the gas bubble moved along the tube at 10cm from the light was 72mm.

The diameter of the narrow tube was 1mm.

Calculate the volume of water taken up by the plant.

Use the equation: volume = πr²l
where r is the radius of the tube and l is the distance the bubble moves
π = 3.14

Give your answer to 2 significant figures.

Volume of water = ................. mm³ /minute [3]

(ii)

Identify the anomalous reading in their recorded results and suggest a possible reason for this.

(iii)

(iv)

The scientists described their results for 20cm as 73 ± 2.
Explain why they did this.

Stomata are found on the surface of leaves.

The diagram shows some of the surface cells of a leaf.

(i)

Write down the name of the cell labelled X.

(ii)

Describe two functions of stomata.

Rheumatic fever is a rare disease in the UK.

Look at this information.

(i)

Put ticks (✓) in the two boxes that best describe rheumatic fever.

[1]

People who have this leaky valve often have these symptoms:

• they get out of breath easily
• they do not seem to have much energy and feel tired.

Write about the job of this valve and how damage to the valve may cause these symptoms.

Look at the graph.

• It gives data about people of different ages.
• It shows the number of cases of rheumatic fever.
• It also shows the number of new cases of heart problems caused by rheumatic fever.

[2]

Look at the diagram. It represents the human circulatory system.

Describe how the diagram shows that humans have a double circulatory system.

Look at the diagrams of the circulation systems in an amphibian, bird and fish.
Which of these has a circulatory system most similar to humans?

Tick (✓) one box.

Explain your choice.

Scientists investigate how exercise affects blood flow to different organs in the body.

This is their method.

• Ask a healthy person to sit in a room at 20°C
• Measure the blood flow to different organs in the person’s body
• Repeat this with the person exercising at a constant speed on a treadmill in the same room.

The table shows the scientists’ results.

(i)

By how many times has the total blood flow increased by doing exercise?

Give your answer to the nearest whole number.

Number of times the total blood flow has increased = ......................................... [2]