Practical 9- Investigation into the effect of enzyme or substrate concentration on enzyme activity

Question 1

Where is the enzyme catalase found?

Answer 1

In all living tissue - is produced by any eukaryotic cell

Question 2

Which type of enzyme is found in all living tissue and is produced by any eukaryotic cell?

Answer 2

Catalase

Question 3

What does the enzyme catalase do?

Answer 3

Increases the break down of hydrogen peroxide, a toxin produced as a by-product of metabolic reactions in cells

Question 4

Which enzyme breaks down hydrogen peroxide?

Answer 4

Catalase

Question 5

Hydrogen peroxide

Answer 5

A toxin produced as a by-product of metabolic reactions in cells

Question 6

What is hydrogen peroxide in this practical?

Answer 6

The substrate

Question 7

What’s the substrate in this practical?

Answer 7

Hydrogen peroxide

Question 8

Describe hydrogen peroxide

Answer 8

Very reactive

Question 9

What’s the risk caused by hydrogen peroxide and why?

Answer 9

Can cause skin irritation as its an oxidising agent

Question 10

Equation for the reaction of catalase

Answer 10

2H202 ——> 2H20 + 02

Question 11

What causes the paper discs to rise to the surface in this practical?

Answer 11

The enzyme catalysed reaction of catalase produced 02, which will form bubbles on the surface of the discs so that they rise to the surface

Question 12

What do the paper discs do in this practical and why?

Answer 12

Rise to the surface of the hydrogen peroxide as the reaction of catalyse produced 02 which forms bubbles on the surface of the discs so that they rise to the surface

Question 13

What is catalase found in high concentrations in?

Answer 13

Raw potatoes

Question 14

Which enzyme is found in high concentrations in raw potatoes?

Answer 14

Catalase

Question 15

What’s the first step of this practical?

Answer 15

Grind a 2cm piece of potato cylinder with 5cm^3 distilled water with a pestle and mortar to make a smooth paste containing the enzyme - the enzyme suspension

Question 16

How big is the potato cylinder used and how much distilled water is it grinded with?

Answer 16

2cm, 5cm^3

Question 17

What’s the name for the paste containing the enzyme created?

Answer 17

The enzyme suspension

Question 18

Enzyme suspension

Answer 18

Smooth paste containing the enzyme catalase and distilled water

Question 19

What do we do after grinding up the potato cylinder to create an enzyme suspension?

Answer 19

Place 10cm^3 of H202 in a specimen tube/test tube - do this for 5 different substrate concentrations - 2vol, 4vol, 6vol, 8vol and 10vol.

Question 20

What do we place in the test tubes and how much?

Answer 20

5 different concentrations of H202
10cm^3

Question 21

What are the 5 different substrate concentrations used?

Answer 21

2vol, 4vol, 6vol, 8vol, 10vol

Question 22

What do we do after filling the test tubes with hydrogen peroxide of different concentrations?

Answer 22

Using forceps, dip a filter paper disc into the enzyme suspension and tap off the excess

Question 23

What’s dipped into the enzyme suspension?

Answer 23

A filter paper disc

Question 24

What happens father dipping the filter paper disc into the enzyme suspension?

Answer 24

Drop the filter paper disc into the hydrogen peroxide solution and measure the time, to the nearest second, that it takes from striking the surface to sink to float up again to the surface

Question 25

What are we measuring the time of?

Answer 25

The time taken for the filter paper disc to strike the surface, to sink and to float up again to the surface of the enzyme suspension

Question 26

What do we do after timing the paper disc in the hydrogen peroxide solution?

Answer 26

Remove the disc from the tube using forceps and discard

Question 27

How many times do we repeat the practical at each concentration of H202?

Answer 27

3x

Question 28

What do we repeat 3 times in this practical?

Answer 28

The process of putting the paper discs in the H202 at each concentration

Question 29

What were the results of this practical?

Answer 29

The higher the substrate concentration, the faster the rate of enzyme activity

Question 30

What made this practical less reliable and accurate?

Answer 30

-Enzyme concentration wasn’t consistent, as potato sample wasn’t completely smooth, so sometimes you’d get entire chunks of potato (and therefore more enzyme) and sometimes none
-There was no timing for dipping the discs into the enzyme suspension
-Timing depended a lot on human reaction time

Question 31

What was wrong with the process of dipping the paper discs into the enzyme suspension?

Answer 31

There was no timing - some discs may have been dipped in for longer or shorter than others

Question 32

What wasn’t consistent in this practical? Why?

Answer 32

Enzyme concentration as the potato sample wasn’t completely smooth, so sometimes you’d get entire chunks of potato (and therefore more enzyme) and sometimes none