Edexcel A-Level Biology Assessed Mathematical Skills

Practise Edexcel A-Level Biology AS and A2 mathematical skills by using biological data for percentages, ratios, graphs, units and standard form.

Covered syllabus points

A.0 Arithmetic and numerical computation A.1 Handling data A.2 Algebra A.3 Graphs A.4 Geometry and trigonometry

[Maximum number: 4]

An abdominal aortic aneurysm (AAA) is a swelling of the aorta in the abdomen due to weakening of the wall of the aorta. Patients with an AAA frequently have atherosclerosis. An AAA can be fatal if the aorta bursts causing internal bleeding. The diagram shows an AAA.

Figure for Question Assessed mathematical skills and measurement conventions question 1 — Edexcel A-Level Biology AS

(a)

The presence of an AAA can be detected by scanning the abdomen. The image shows a scan of a healthy abdominal aorta.

Figure for Question (a) — Edexcel A-Level Biology AS

[ 4 ]

(i)

The diameter of this aorta, between X and Y , is 17.3 mm . Calculate the magnification of this image. Give your answer to a suitable number of decimal places.

[ 2 ]

measured diameter divided by actual diameter (1)

- 0.69 / 0.7 / 0.75 / 0.8 / 0.81 (1)

$12 \div 17.3=0.693641$ $13 \div 17.3=0.751445$ $14 \div 17.3=0.809249$

Bald answer of 0.69 / 0.7 / 0.75 / 0.8 / 0.81 = 2 marks

Bald answer of 0.693641 / 0.751445 / 0.809249 correctly rounded to more than 2 dps=1 mark

(ii)

An aorta with a diameter greater than 5.5 cm is classed as a large AAA. Calculate how many times wider this large AAA is than the aorta with a diameter of 17.3 mm . Give your answer to three significant figures.

[ 1 ]

(iii)

A screening programme found that 1 in 92 men had an AAA and 1 in 1000 men had a large AAA. Calculate the proportion of AAA that are large AAA.

[ 1 ]

[Maximum number: 2]

Sickle cell disease is caused by a gene mutation affecting the $\beta$ -globin chain of haemoglobin.

The red blood cells in a person with sickle cell disease are sickle shaped and less elastic. They also have a shorter lifespan than healthy red blood cells.

These sickle shaped red blood cells cannot carry as much oxygen as healthy red blood cells and they get stuck in the capillaries.

The graph shows oxygen dissociation curves for groups of people with sickle cell disease and those without the disease.

The shaded areas represent the range of values for each group of people.

Percentage of haemoglobin saturated with oxygen (\%)

Figure for Question Assessed mathematical skills and measurement conventions question 2 — Edexcel A-Level Biology AS

A p50 value is the partial pressure of oxygen that results in 50\% saturation of haemoglobin.

Calculate the largest difference in the p50 values between a person with sickle cell disease and a person without this disease.

Give your answer to an appropriate number of decimal places.

[Maximum number: 3]

A student used a microscope to study the tissues in a plant stem and the cell of an animal.

The photograph shows a vascular bundle in a transverse section of the plant stem, as seen using a light microscope.

Figure for Question Assessed mathematical skills and measurement conventions question 3 — Edexcel A-Level Biology AS

(a)

This photograph shows a high-power view of some of the cells in tissue C in the vascular bundle.

Each of the smallest units on the eyepiece graticule shown in the photograph is $3 \times 10^{-6} \mathrm{~m}$ .

Assume that the cell labelled F in the photograph is circular.
Calculate the cross-sectional area of cell F .

Answer

[ 2 ]

An answer that includes the following steps:

- measurement of cell \{diameter / radius\} in epg units and conversion to m (1)

- calculation of area using $\pi \mathrm{r}^{2}(1)$

ACCEPT 14 to 14.5 as alternatives to 13.

e.g.

$\{13 / 6.5\} \times 3 \times 10^{-6}=39 \times 10^{-6}=3.9 \times 10^{-5}$

OR $19.5 \times 10^{-6}=1.95 \times 10^{-5}$ $\pi \times\left(\left(1.95 \times 10^{-5}\right)^{2}\right)=1.195 \times 10^{-9}$

OR $3.14 \times 3.8025 \times 10^{-10}=1.194 \times 10^{-9}$

ACCEPT 1.195, 1.19, 1.2

If include units must match answer, but units not needed

(2)

(b)

A cell in tissue B of the vascular bundle has a cross-sectional area of $6.13 \times 10^{-11} \mathrm{~m}^{2}$ .

Calculate how many times larger the cross-sectional area of cell F is than this cell in tissue B.

Give your answer to three significant figures.

Answer

[ 1 ]

division of area of F by area given of E
(1)

ecf from 1aiii

eg

$1.194 \div 0.0613=19.5$ times

(1)

[Maximum number: 2]

There are many water-stressed countries in the world, mostly in the Middle East, North Africa and South Asia. Water-stressed countries have a shortage of fresh water needed for humans, animals and crops. Fresh water can be produced from sea water by desalination processes. The map shows the most water-stressed countries (shaded) in the world.

Figure for Question Assessed mathematical skills and measurement conventions question 4 — Edexcel A-Level Biology AS

The estimate of the volume of water on Earth is $1.4 \times 10^{12} \mathrm{~km}^{3}$ . Fresh water makes up 2.5\% of this volume. 90\% of this fresh water is not available as it is frozen in ice caps and glaciers. Calculate the volume of available fresh water on Earth. Give your answer in standard form.

(volume of freshwater calculated as) $3.5 \times 10^{10}(1)$

- $3.5 \times 10^{9}\left(\mathrm{~km}^{3}\right)(1)$

ACCEPT $3.5 \cdot 10^{10}$ incorrect standard form e.g. $0.035 \times 10^{12}$

ACCEPT $3.50 \times 10^{9} / 3.5 \cdot 10^{9}$

Bald answer of $3.5 \times 10^{9}=2$ marks Bald answer of correct answer but in incorrect standard form = 1 mark correct answer for volume of freshwater in correct standard form $\left(3.5 \times 10^{10}\right)=1$ mark

All question bank results loaded

Covered syllabus points

Assessed mathematical skills and measurement conventions question 1

Question (a)

Question (i)

Question (ii)

Question (iii)

Assessed mathematical skills and measurement conventions question 2

Assessed mathematical skills and measurement conventions question 3

Question (a)

Question (b)

Assessed mathematical skills and measurement conventions question 4