Edexcel IGCSE Biology Mathematical Skills

Practise Edexcel IGCSE Biology mathematical skills by calculating BMI, percentages and population values from biological tables and data.

[Maximum number: 3]

The diagram shows a fetus in the uterus of a woman.

Figure for Question 7 Mathematical skills question 1 — Edexcel IGCSE Biology

The umbilical cord transports blood from the placenta to the fetus.
This blood contains molecules from the mother that are needed by the developing fetus.

Doctors recommend that pregnant women obtain more of some dietary components than women who are not pregnant.

The table shows the recommended percentage increase of some dietary components in the diet of a woman who is pregnant compared to a woman who is not pregnant.

Table for Question 7 Mathematical skills question 1 — Edexcel IGCSE Biology

The actual mass of additional iron needed by the pregnant woman was 9.0 mg per day.

Calculate the actual total mass of iron needed by the pregnant woman.

9=50 % more

- $100 \%=9 \times 2=18$

- 18+9=27(1)

Allow one mark for 0.5 / 50\% / 1/2 / times 2

Allow 18 for two marks

Award full marks for correct numerical answer without working

exp

[Maximum number: 2]

The human kidney is an organ that is able to process excretory products from human metabolism.

Concentration of urine is calculated using this formula.

\text { concentration in milliosmoles per } \mathrm{dm}^{3}=\frac{\text { amount of waste in milliosmoles }}{\text { volume in } \mathrm{dm}^{3}}

The amount of waste the kidneys produce per day is 600 milliosmoles.
The maximum concentration that the human kidneys can produce is 1400 milliosmoles per $\mathrm{dm}^{3}$ .

Calculate the minimum volume of urine that must be produced each day.
Give your answer in $\mathrm{cm}^{3}$ .
minimum volume = $\mathrm{cm}^{3}$

600 / 1400

- $0.43 \mathrm{dm}^{3}=$

- 430

one mark for 600 /1400 or one mark for 0.43/ eq

full marks for correct answer with no working

allow 429 / 428.57 or 428.6 / eq

[Maximum number: 4]

Neurones transmit nerve impulses.
The diagram shows a neurone.

Figure for Question 7 Mathematical skills question 3 — Edexcel IGCSE Biology

(a)

Some neurones do not have a myelin sheath.

A scientist investigates the impulse speed for neurones with different diameters. She does this for neurones with a myelin sheath and neurones without a myelin sheath.

The graph shows the scientist's results.

Impulse speed in m per s

Figure for Question (a) — Edexcel IGCSE Biology

[ 4 ]

(i)

A neurone with a myelin sheath has a diameter of $1.0 \mu \mathrm{~m}$ .

Use the graph to determine the speed of an impulse in this neurone.
speed = m per s

[ 1 ]

(ii)

The neurone is 90 cm long.

Calculate the time taken for an impulse to travel along this neurone.
Give your answer in standard form.
time $=\ldots$ .
s

[ 3 ]

$90 \mathrm{~cm}=0.9 \mathrm{~m}$

- $90 \div($ speed ) 440= 0.20s

$0.9 \div$ (speed) 4.4 $=0.20 \mathrm{~s}$

= seconds

- $2.0 \times 10^{-1}(3)$

award full marks for correct numerical answer without working regardless of speed used

allow 1 mark for 0.9 (m) or speed expressed as × $100 \mathrm{~cm} / \mathrm{s}$ ( 440 idea)

allow 1 mark for $90 \div$ speed or $0.9 \div$ speed

(if not 0.20455 etc)

allow 2 marks for marks for correct numerical answer without working but not in standard form

All question bank results loaded

Covered syllabus points

7 Mathematical skills question 1

7 Mathematical skills question 2

7 Mathematical skills question 3

Question (a)

Question (i)

Question (ii)