Module 2 Chapter 4 Lesson 9 - Measuring Enzyme Activity

Question 1

What is enzyme activity?

Answer 1

Rate of product formation

Question 2

How can enzyme activity be measured?

Answer 2

Product formed or substrate used

Question 3

What enzyme is commonly used in OCR practicals?

Answer 3

Catalase

Question 4

What substrate does catalase break down?

Answer 4

Hydrogen peroxide

Question 5

What products are formed?

Answer 5

Water and oxygen

Question 6

How can oxygen production be measured?

Answer 6

Gas syringe

Question 7

What unit is enzyme activity measured in?

Answer 7

Rate per second

Question 8

Why is catalase practical suitable?

Answer 8

Fast and measurable

Question 9

How is temperature controlled in experiments?

Answer 9

Water bath

Question 10

How is pH controlled?

Answer 10

Buffer solutions

Question 11

What must be kept constant?

Answer 11

All variables except one

Question 12

Why are repeats important?

Answer 12

Improve reliability

Question 13

What is a control experiment?

Answer 13

No enzyme present

Question 14

Why is initial rate measured?

Answer 14

Most accurate

Question 15

What safety precaution is needed?

Answer 15

Eye protection

Question 16

Why is hydrogen peroxide hazardous?

Answer 16

Irritant

Question 17

What graph is plotted?

Answer 17

Rate vs variable

Question 18

How is rate calculated?

Answer 18

Volume divided by time

Question 19

What is meant by initial rate?

Answer 19

Rate at start of reaction

Question 20

Why is initial rate the most accurate?

Answer 20

Substrate concentration unchanged

Question 21

Why is product inhibition avoided at initial rate?

Answer 21

Products not accumulated

Question 22

Why is enzyme denaturation minimal at initial rate?

Answer 22

Short reaction time

Question 23

How is initial rate calculated from a graph?

Answer 23

Gradient at time zero

Question 24

Why should the steepest part of the curve be used?

Answer 24

Reflects maximum activity

Question 25

What units are used for enzyme activity?

Answer 25

cm³ s⁻¹

Question 26

Why is rate preferred over total product?

Answer 26

Allows fair comparison

Question 27

What happens to rate as substrate is used up?

Answer 27

It decreases

Question 28

Why is the initial rate linear?

Answer 28

Active sites not saturated by products

Question 29

What error can occur when fitting the bung?

Answer 29

Oxygen lost before sealing

Question 30

Why can oxygen volume be underestimated?

Answer 30

Oxygen dissolves in solution

Question 31

How can syringe readings be inaccurate?

Answer 31

Human parallax error

Question 32

Why can temperature fluctuate?

Answer 32

Heat loss to surroundings

Question 33

How can enzyme denaturation affect results?

Answer 33

Lower rate over time

Question 34

Why does foam formation cause error?

Answer 34

Traps oxygen

Question 35

How can reliability be improved?

Answer 35

Repeats and mean calculation

Question 36

How can accuracy be improved?

Answer 36

Use data logger

Question 37

How can temperature be stabilised?

Answer 37

Insulated water bath

Question 38

Why is catalase concentration difficult to control?

Answer 38

Biological variation

Question 39

Question

Answer 39

Answer

Question 40

How is pH controlled in enzyme experiments?

Answer 40

Using buffer solutions

Question 41

How is temperature controlled accurately?

Answer 41

Thermostatically controlled water bath

Question 42

How is enzyme concentration controlled?

Answer 42

Same volume and concentration

Question 43

How is substrate concentration controlled?

Answer 43

Serial dilution

Question 44

Why must enzyme concentration be constant?

Answer 44

To ensure valid comparison

Question 45

Why must temperature be controlled?

Answer 45

Affects kinetic energy

Question 46

Why must pH be controlled?

Answer 46

Affects ionic bonds

Question 47

Why must volume be controlled?

Answer 47

Affects collision frequency

Question 48

What is a control experiment?

Answer 48

No enzyme present

Question 49

Why is a control experiment used?

Answer 49

Ensure results due to enzyme