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Edexcel IGCSE Biology Algebra Skills

Practise Edexcel IGCSE Biology algebra skills by substituting biological values into formulae for BMI, impulse time and urine concentration.

Syllabus
Issue 3 (2024)
Course
Biology 4BI1

Exam points

  • Substitute mass and height into the BMI formula after converting height into metres.
  • Calculate nerve impulse time from distance and speed after converting centimetres to metres.
  • Use concentration equals amount divided by volume to calculate urine volume.

Covered syllabus points

3B Change the subject of an equation3C Substitute values with units3D Solve simple algebraic equations

3 Algebra question 1

[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.

 concentration in milliosmoles per dm3= amount of waste in milliosmoles  volume in dm3\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 dm3\mathrm{dm}^{3}.

Calculate the minimum volume of urine that must be produced each day.
Give your answer in cm3\mathrm{cm}^{3}.
minimum volume = cm3\mathrm{cm}^{3}

3 Algebra question 2

[Maximum number: 3]

The body mass index (BMI) is a measure that uses your mass and height to calculate if your mass is appropriate for your height.

BMI is calculated using the formula

BMI= mass in kg÷( height in m)2\mathrm{BMI}=\text { mass in } \mathrm{kg} \div(\text { height in } \mathrm{m})^{2}

Question (a)

(a)

Person X has a mass of 60 kg and a height of 165 cm .

Calculate the BMI of person X.

[ 2 ]

Question (b)

(b)

BMI values can be divided into categories.

The table shows these categories.

Table for Question (b) — Edexcel IGCSE Biology

Give the category of person X.

[ 1 ]
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