A-Level Edexcel Biology Substitution into Equations

Review A-Level Edexcel Biology substitution into algebraic equations through MAP, enzyme-rate, cardiac-index and BMI calculations from graphs or tables.

Exam points

substitute graph or table values into MAP, rate, cardiac index and BMI formulae
state or derive biological calculation units such as cardiac index units
calculate missing biological quantities after substituting values into supplied equations

[Maximum number: 3]

The human body responds to changes in both its internal and external environments.

The heart responds to adrenaline by increasing cardiac output.

Cardiac output = heart rate × stroke volume

The formula shows how to calculate the cardiac index. This is a method of adjusting cardiac output values for the body surface area of an individual.

\text { cardiac index }=\frac{\text { cardiac output in } \mathrm{dm}^{3} \mathrm{~min}^{-1}}{\text { body surface area in } \mathrm{m}^{2}}

The table shows some information for cardiac output, body surface area and cardiac index for two individuals.

Table for Question A.2.3—Substitution into algebraic equations question 1 — Edexcel A-Level Biology A2

Complete the table to show the units for cardiac index, the cardiac index for individual A and the cardiac output for individual B .

A calculation showing the following steps:

- calculation of cardiac output (1)

- correct unit stated (1)

- calculation of cardiac index (1)

mp 1 for $(1.49 \times 2.8)=4.2$ /4.17 / 4.172

mp 2 for $\mathrm{dm}^{3} \mathrm{~min}^{-1} \mathrm{~m}^{-2}$ ACCEPT $\mathrm{dm}^{3} \mathrm{~m}^{-2} \mathrm{~min}^{-1}$ ACCEPT $\mathrm{dm}^{3}$ per min per $\mathrm{m}^{2}$

Mp3 for (6.9/1.92) =3.5 / 3.49 / 3.489

ACCEPT values / units in working if table is empty (or by formula)

(3)

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A.2.3—Substitution into algebraic equations question 1