A-Level Edexcel Biology AS Tangents and Instantaneous Rates

A-Level Edexcel Biology AS Tangents and Instantaneous Rates
Pearson Edexcel International Advanced Subsidiary/Advanced Level in Biology, Issue 2, February 2021Biology XBI11/YBI11

Review A-Level Edexcel Biology tangents and instantaneous rates through reaction curves, initial gradients, oxygen production and rate-unit calculations.

How this is tested

  • draw tangents to reaction curves and calculate instantaneous rates at stated times
  • plot mass or product against time and use the starting gradient for initial rate
  • round tangent-gradient rates to required precision with biological rate units

Question 2(b)(i)

[Maximum number: 2]

Polyphenol oxidase is an enzyme found in avocados.
This enzyme causes green avocados to go brown when they are cut open.
The equation shows the reaction catalysed by this enzyme.

monophenol ⟶ o-diphenol

The graph shows the change in monophenol concentration in the presence of polyphenol oxidase, at a temperature of 25∘C25^{\circ} \mathrm{C}.

Figure for Question 2(b)(i) — Edexcel A-Level Biology AS

Calculate the rate of reaction at 3 minutes. Draw a tangent to help with your calculation. (i) Calculate the rate of reaction at 3 minutes. Draw a tangent to help with your calculation / mmoldm−3min⁡−1\mathrm{mmol} \mathrm{dm}^{-3} \min ^{-1}