CIE A Level Biology (9700) 2019-2021

Revision Notes

3.2.3 Rate: Enzyme Concentration

Rate: Enzyme Concentration

  • Enzyme concentration affects the rate of reaction
  • The higher the enzyme concentration in a reaction mixture, the greater the number of active sites available and the greater the likelihood of enzyme-substrate complex formation
  • As long as there is sufficient substrate available, the initial rate of reaction increases linearly with enzyme concentration
  • If the amount of substrate is limited, at a certain point any further increase in enzyme concentration will not increase the reaction rate as the amount of substrate becomes a limiting factor


Alistair graduated from Oxford University in 2014 with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems and Societies.

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