Investigating a Factor that Affects Enzyme Activity

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Investigating a Factor that Affects Enzyme Activity

Planning

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Aim

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To investigate a factor which will affect the activity of catalase,

whilst keeping all variables constant.

Possible Independent Variables

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Here are a number of possible independent variables that could be

changed in the experiment:

Independent variable

Continuous/Discontinuous

Easy to measure?

Volume of substrate used

Continuous

Yes

Type of enzyme

Discontinuous

Yes

Overall mass of piece of meat

Continuous

No

Type of substrate used

Discontinuous

Yes

Temperature of substrate

Continuous

Yes

pH of substrate

Continuous

No

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Concentration of substrate used

Continuous

Yes

The independent variable I have chosen, or the one to be changed

throughout the experiment will be 'the concentration of substrate

used', which will range from 0.25M to 1.25M with increments of 0.25M.

With reference to the table above, it has been chosen, as it is

continuous (i.e. it has a numerical value of some sort and this can be

altered) so the results can facilitate a graph.

Dependent Variable

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Rate at which the bubbles of oxygen rise, which will be calculated by

observing how many bubbles of oxygen rise to the surface of a

measuring cylinder (by means of downward displacement) in one minute.

This will be measured in bubbles per ten seconds.

Control variables:

¨ Volume of substrate used: 100ml

¨ Temperature: taken place at room temperature 21 degrees centigrade

¨ Type of substrate used: Hydrogen peroxide

¨ Mass of meat used: 5g

¨ Amount of water in the test tube in which the oxygen bubbles

downward displaces in the water. This is so the time taken for each

individual bubble to effectively rise to the bottom of the test tube

will take the same amount of time.

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