Core Practical 4

Question 1

What is the independent variable for the effect of the changing substrate concentration on initial rate of reaction?

Answer 1

Substrate concentration

Question 2

What is the dependent variable for the effect of the changing substrate concentration on initial rate of reaction?

Answer 2

Volume of oxygen produced

Question 3

What are the control variables for the effect of the changing substrate concentration on initial rate of reaction?

Answer 3

Thickness of potato discs
Temperature
Enzyme concentration
Number of potato discs
Variety of potatos

Question 4

What is the method for the effect of the changing substrate concentration on initial rate of reaction?

Answer 4

• Use range of different concentrations of substrate (at least 5)
• use same amoung of potato discs which are same thickness each time.
• Add 2ml of buffer solution and 10ml of the lowest concentration of substrate to potato discs and attach bung immediately.
• record the volume of oxygen produced every 10s for 2mins on gas syringe.
• repeat the remaining concentrations of substrate solution.
• draw graphs of volume of oxygen produced against time and calculate the initial rate of reaction for each substrate concentration.
• plot a graph of initial rate of reaction against substrate reaction.

Question 5

What is the outcome for the effect of the changing substrate concentration on initial rate of reaction?

Answer 5

As substrate concentration increases the initial rate of reaction increases to a point and then it stays constant. (Explain why…)

Question 6

What are the possible evaluation issues with the effect of the changing substrate concentration on initial rate of reaction experiment?

Answer 6

• maintaining constant temperature
• ensuring all the potato discs are the same width
• ensuring all the potato discs ate in contact with substrate
• losing some oxygen as bung is added to the conicak flask
• reading the gas syringe accurately as the plunger moves quickly.

Question 7

What is the independent variable for the effect of the changing enzyme concentration on initial rate of reaction?

Answer 7

Enzyme concentration

Question 8

What is the dependent variable for the effect of the changing enzyme concentration on initial rate of reaction?

Answer 8

Volume of oxygen produced

Question 9

What are the control variables for the effect of the changing enzyme concentration on initial rate of reaction?

Answer 9

Temperature
Volume of substrate
Concentration of substrate
PH

Question 10

What is the method for the effect of the changing enzyme concentration on initial rate of reaction?

Answer 10

• use a range of concentrations of enzymes.
• there should be enough substrate molecules to saturate the enzyme to ensure the substrate isn’t a limiting factor
• add 2ml of buffer solution and 10ml of substrate solution to a conical flask and add the potato disks and attach bung immediately.
• Record the volume of oxygen produced every 10s for 2mins on the gas syringe.
• repeat for the remaining potato discs
• control with no enzyme for comparison

Question 11

What is the outcome for the effect of the changing enzyme concentration on initial rate of reaction?

Answer 11

As enzyme concentration increases the initial rate of reaction increases. (Explain why…)

Question 12

What are the possible evaluation issues with the effect of the changing enzyme concentration on initial rate of reaction experiment?

Answer 12

• maintaining constant temperature
• ensuring all the potato discs are the same width
• ensuring all the potato discs are in contact with the substrate
• losing some oxygen as bung is added to conical flask
• reading the gas syringe accurately as the plunger moves.