Answers to last week's questions
Monacia Williams, Contributor

Well, hello again. Did you attempt the questions that I left you with last week? I hope you did and you are now ready to compare your answers with mine.

By now you should have realised that these questions are based on a popular SBA laboratory exercise, one that you might have already done. They are also good choices for the first question on the biology paper 2, so pay careful attention to the answers.

Answers

a) The term used to describe glucose is monosaccharide.

b) i) A suitable aim for the experiment would be:

To demonstrate the effect of increasing the concentration of amylase on the time taken to digest starch.

ii) A suitable title for the table would be:

Table showing the effects of increasing concentrations of amylase on the digestion of starch.

ii)

iv) Describe how increasing the concentration of the enzyme affected the time taken for the starch to be digested.

As the concentration of amylase increased, the time taken to digest starch decreased. For example, at 0.10 per cent, the time taken was 950 seconds, while at 2.00 per cent, the time taken was 160 seconds.

c) Suggest why 40ºC was chosen as the temperature at which the experiment would be carried out.

40ºC was chosen as the temperature at which the experiment was carried out because this temperature was the one nearest to the enzymes optimum temperature. The optimum temperature is the temperature at which the enzyme works best.

d) Describe one way that the students could have kept the temperature constant at 40ºC.

The temperature could have been kept constant with the use of a water bath.

e) Suggest what would happen to the time taken for the starch to be digested at 20ºC and 80ºC. In each case give a reason for your answer.

The time taken at 20ºC would be longer than that taken at 40ºC. This is because the enzyme would be deactivated at this low temperature. The kinetic energy of the molecules would be low and fewer enzyme and substrate molecules would meet.

At 80ºC the time taken would be even longer since it is not expected that the reaction would take place. The high temperature would denature the enzyme destroying its active site so the substrate could no longer react with it.

How did you do? Were your answers close to mine? If they were not, I suggest that you review this topic because it is a very important one. See you next week when we begin to look at respiration. Have a good week!

Dunoon Technical High school students really came to the offices of The Gleaner company and donated food and clothing to the children of Martha's House that was recently burnt down. The students (from left) Phillip Kinghorn, Patrice Roberts, Crystal Mitchell (head girl), Michael Ennis, Everald Henry (deputy head boy) and Oquain Cameron, present the items to Terry Wilson, Gleaner's Corporate Affairs Officer. The students were assisted by Aldith Douglas, a teacher at the school to collect and take the items to The Gleaner. - Ian Allen/Staff Photographer