Paper 4 · November 2003 · Enzymes
In this investigation catalase activity was measured by timing how long it took manometer fluid to rise 5 cm in a boiling tube containing potato discs, buffer and hydrogen peroxide. After adding the hydrogen peroxide and replacing the bung, the tube was shaken gently. State the reason the tube was shaken.
Model answer
to separate the discs
Also accepted: to increase surface area, to speed up diffusion of hydrogen peroxide into the discs, to increase the surface area of the discs so hydrogen peroxide diffuses in faster, to mix the reactants thoroughly
Explanation
Shaking separates the potato discs, increasing the surface area exposed to the hydrogen peroxide and so speeding diffusion of H2O2 into the discs.
Derived from ZIMSEC Biology 9190/4 Paper 4 (Practical Test), November 2003, Q1