Factors Affecting The Rate Of Enzyme-Controlled Reactions

Question 1

What are the four factors that affect enzyme activity?

Answer 1

pH
Temperature
enzyme concentration
Substrate concentration

Question 2

How is the rate of rate of reaction calculated for the measurement of time?

Answer 2

Rate of reaction = 1/ time, S-1

Question 3

What is the risk and level of risk associated with handling enzymes?

Answer 3

Students may have allergic reactions to enzymes, so avoid contact with skin and eyes, wear eye protection.

Question 4

What two ways can you measure the rate of an enzyme-controlled reaction?

Answer 4

1. You can measure how fast the products of the reaction are made.
2. you can measure how fast the substrates are broken down.

Question 5

What enzyme catalyses hydrogen peroxide?

Answer 5

Catalase

Question 6

What are the products of the reaction of hydrogen peroxide and it’s enzyme

Answer 6

Water and oxygen

Question 7

How can you measure the rate of reaction using hydrogen peroxide and catalase?

Answer 7

Measure the VOLUME of oxygen gas produced over a given time

Question 8

State the word equation of the action of catalase

Answer 8

Hydrogen peroxide -> water + oxygen

Question 9

What is the independent variable in the practical?

Answer 9

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

Question 10

What is the dependent variable?

Answer 10

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

Question 11

Give an example of a control variable

Answer 11

A buffer solution

Question 12

How do you determine the uncertainty?

Answer 12

Scale intervals e.g, 1C/ 2

Question 13

When calculating uncertainty, smaller intervals will have what?

Answer 13

a smaller uncertainty

Question 14

Once you have gotten a range of values, what should be calculated?

Answer 14

The mean

Question 15

When will your ability to present graphs be accessed?

Answer 15

In written papers also in the practical endorsement

Question 16

What scales should be used for graphs?

Answer 16

Easier scales such as 2, 5, 10.

Question 17

Which axis should have the independent variable?

Answer 17

The x-axis

Question 18

Which axis should have the dependent variable?

Answer 18

The y-axis

Question 19

How should your points be plotted?

Answer 19

Using saltire crosses (x)

Question 20

How should each point be joined together?

Answer 20

Using straight lines, ruler

Question 21

Once your graph has been plotted, how should you apply your knowledge?

Answer 21

Describe the trend, overall pattern of your results using terms such as increase/decrease, plateau/level off, maximum and directly proportional.

Question 22

Note

Answer 22

Label the main sections of the graph, e.g. A,B,C.

Question 23

What can you not conclude if you do not have intermediate results?

Answer 23

An optimum temperature

Question 24

When the rate of reaction increases, how can this be explained with temperature effect?

Answer 24

Increased temperature, increases kinetic energy and number of collisions and the formation of ENZYME-SUBSTRATE COMPLEXES

Question 25

What maths skills are involved in this practical?

Answer 25

Drawing a tangent

Question 26

How is the gradient calculated?

Answer 26

change in y-axis/ change in x-axis

Question 27

What variables can be controlled in an enzyme reaction with the effect of pH

Answer 27

• Concentration of enzyme and temperature
• volume of enzyme and pH

Question 28

How should a thermometer be used when monitoring temperature?

Answer 28

Check the temperature every 10 minutes to make sure it remains constant

Question 29

Specificity of collisions

Answer 29

Successful collisions

Question 30

Why are the graphs drawn with straight lines?

Answer 30

Because the person cannot be sure of the intermediate values

Question 31

Give reason for why optimum values cannot be valid?

Answer 31

The student needs to to repeat the investigation using other number/ scale of factors

Question 32

How can a student ensure that decisions are consistent when comparing solutions?

Answer 32

Compare the color of each sample to a sample of reaction mixture that has gone to completion and been tested

Question 33

What is a control variable?

Answer 33

The variable in an experiment is kept constant in order to access the relationship between other variables