B3 - enzymes RP

Question 1

what is the purpose of the enzymes required practical

Answer 1

to find out what happens to the rate of enzyme activity when the pH changes

Question 2

what other variable can be measured instead of pH in the enzymes required practical

Answer 2

temperature

Question 3

what is the risk assessment from the enzymes required practical

Answer 3

• iodine/enzyme solution - could irritate skin so wash hands immediately after spillage
• pH buffer solutions - could be corrosive so wear eye protection and take care

Question 4

what is the method for the enzyme required practical

Answer 4

1. put a test tube of amylase and test tube of starch in a water bath until they are both the same temperature
2. add amylase to the starch
3. every 30 seconds, remove a drop and add it to a spotting tile containing iodine solution
4. record how long it takes for the starch to be completely digested
5. repeat this at different pH values using different buffer solutions

Question 5

what are the results of the enzyme required practical

Answer 5

• if the iodine solution changes to blue/black it means starch is present (hasn’t been fully digested)
• the more active the enzyme is (closer to its optimum) the quicker it will be until the iodine solution stays orange/brown

Question 6

what is the independent variable in the enzyme required practical

Answer 6

the pH

Question 7

what is the dependent variable in the enzyme required practical

Answer 7

time taken for amylase to digest starch

Question 8

what are the control variables in the enzyme required practical

Answer 8

temperature, concentration of amylase, starting concentration of starch

Question 9

identify sources of error in the enzyme required practical

Answer 9

subjunctive measurement

Question 10

why do you need a water bath in the enzyme required practical

Answer 10

to maintain the temperature, because it affects the rate of reaction

Question 11

explain the results of the enzyme required practical using knowledge of enzymes

Answer 11

at pH values that are too high/too low compared to the optimum pH, the enzyme will denature

Question 12

why can’t we know the exact optimum pH in the enzyme required practical

Answer 12

it could be between 2 numbers e.g. 7 and 8 so you need to test different smaller pH intervals between these values to determine the optimum more accurately