Required Practical 1 - Enzymes

Question 1

Investigation title

Answer 1

Investigation into the effect of a named variable on the rate of an enzyme controlled reaction (temperature on the rate of the reaction catalysed)

Question 2

How is the control set up

Answer 2

• replace the enzyme solution with distilled water or boiled enzyme solution

Question 3

How can the results be used to find the initial rate of reaction

Answer 3

• plot results on a graph of rate of reaction against time

- draw tangent line from 0 to find initial rate of reaction

Question 4

How is rate of reaction calculated from time

Answer 4

Rate of reaction = 1/time

Question 5

Effect of temperature on activity

Answer 5

• as temperature increases the kinetic energy increases so more es complexes are formed
• rate of reaction increases up till the optimum temperature
• too high and then the tertiary structure changes and aren’t complementary

Question 6

Risks and preventions

Answer 6

• allergic to enzyme (biohazard)
• avoid contact to skin
• wear eye protection

Question 7

Method

Answer 7

1. six tubes in the water bath for 10 minutes.
2. Add the trypsin and buffer solution from one test tube to the solution of milk powder in another test tube.
3. Put a bung in the test tube and invert 5 times to mix.
4. Put the test tube back into the water bath. Time the reaction for 4 minutes.
5. Pour the into a cuvette and measure the absorbance.
6. Repeat steps using other test tubes you set up.

Question 8

method for changing the substrate concentration

Answer 8

• use a range of at least 5 different substrate concentrations
• use an enzyme volume and concentration that does not limit the rate of reaction
• identify an observant dependent variable eg colour change/ volume of gas produced
• record the time using a stop watch
• calculate the initial rate of reaction (pot of graph, draw tangent, change on y/change on x)
• use a suitable control
• repeat at least 5 times for each concentration
• control other variables

Question 9

method for changing enzyme concentration

Answer 9

• use a range of at least 5 different enzyme concentrations
• use a substrate volume and concentration that doesn’t limit the rate of reaction
• identify an observant dependent variable eg colour change/ volume of gas produced
• record the time using a stop watch
• calculate the initial rate of reaction (pot of graph, draw tangent, change on y/change on x)
• use a suitable control
• repeat at least 5 times for each concentration
• control other variables

Question 10

what are the other variables to control when changing the substrate concentration

Answer 10

• substrate volume
• enzyme concentration
• temperature
• pH (use a buffer)

Question 11

what are the other variables to control when changing the enzyme concentration

Answer 11

• enzyme volume
• substrate volume and concentration
• temperature
• pH (use a buffer)