Factors Affecting The Rate Of Enzyme-Controlled Reactions Flashcards
What are the four factors that affect enzyme activity?
pH
Temperature
enzyme concentration
Substrate concentration
How is the rate of rate of reaction calculated for the measurement of time?
Rate of reaction = 1/ time, S-1
What is the risk and level of risk associated with handling enzymes?
Students may have allergic reactions to enzymes, so avoid contact with skin and eyes, wear eye protection.
What two ways can you measure the rate of an enzyme-controlled reaction?
- You can measure how fast the products of the reaction are made.
- you can measure how fast the substrates are broken down.
What enzyme catalyses hydrogen peroxide?
Catalase
What are the products of the reaction of hydrogen peroxide and it’s enzyme
Water and oxygen
How can you measure the rate of reaction using hydrogen peroxide and catalase?
Measure the VOLUME of oxygen gas produced over a given time
State the word equation of the action of catalase
Hydrogen peroxide -> water + oxygen
What is the independent variable in the practical?
One of the five factors that affect the rate of reaction. e.g. temperature, Ph etc.. you will be given the value of pH to be used
What is the dependent variable?
A measurement of the time taken for the reaction to be complete. it could either be the time taken for the substrates to be used up/ products to form
Give an example of a control variable
A buffer solution
How do you determine the uncertainty?
Scale intervals e.g, 1C/ 2
When calculating uncertainty, smaller intervals will have what?
a smaller uncertainty
Once you have gotten a range of values, what should be calculated?
The mean
When will your ability to present graphs be accessed?
In written papers also in the practical endorsement
What scales should be used for graphs?
Easier scales such as 2, 5, 10.
Which axis should have the independent variable?
The x-axis
Which axis should have the dependent variable?
The y-axis
How should your points be plotted?
Using saltire crosses (x)
How should each point be joined together?
Using straight lines, ruler
Once your graph has been plotted, how should you apply your knowledge?
Describe the trend, overall pattern of your results using terms such as increase/decrease, plateau/level off, maximum and directly proportional.
Note
Label the main sections of the graph, e.g. A,B,C.
What can you not conclude if you do not have intermediate results?
An optimum temperature
When the rate of reaction increases, how can this be explained with temperature effect?
Increased temperature, increases kinetic energy and number of collisions and the formation of ENZYME-SUBSTRATE COMPLEXES
What maths skills are involved in this practical?
Drawing a tangent
How is the gradient calculated?
change in y-axis/ change in x-axis
What variables can be controlled in an enzyme reaction with the effect of pH
• Concentration of enzyme and temperature
• volume of enzyme and pH
How should a thermometer be used when monitoring temperature?
Check the temperature every 10 minutes to make sure it remains constant
Specificity of collisions
Successful collisions
Why are the graphs drawn with straight lines?
Because the person cannot be sure of the intermediate values
Give reason for why optimum values cannot be valid?
The student needs to to repeat the investigation using other number/ scale of factors
How can a student ensure that decisions are consistent when comparing solutions?
Compare the color of each sample to a sample of reaction mixture that has gone to completion and been tested
What is a control variable?
The variable in an experiment is kept constant in order to access the relationship between other variables
