Questions and answers time
Monacia Williams, Contributor

Well hello again! Did you try to answer the questions I left with you last week? I hope you did. If you did, you can now compare your answers with mine.

The questions were centred on information that was given in the table. This is an important feature of the type of question you might get in an examination, so it is important that you learn how to extract the information from the table.

The answers

a) i) Hamburger

ii) This requires calculation: the table tells you that 100g of hamburger

contains 15g of protein, so 20g will contain 3g hence 120g will contain 15+3 = 18g. Your answer is therefore 18g.

iii) liver (note: the question asks for organ not tissue so muscle would not be correct).

iv) Glycogen

b) I hope that you noticed that there were two parts to this question. You were asked to state two reasons and to give an explanation for each reason. A common mistake that students make is to forget to read the question carefully and hence they do not notice that the question is in two parts.

Answer:

• Vegetable burger has less fat per 100g, therefore there is less chance of fat becoming deposited in the blood vessels.
• vegetable burger has more fibre; fibre helps to lower cholesterol and to prevent constipation.
• vegetable burger provides less energy per 100g; the likelihood of there being excess food left for storage is less, therefore it is less likely to contribute to obesity.

I have given you three possible answers you can choose any two.

Well, how did you do? Did you answer all the questions correctly? If you did, congratulate yourself. You are good! If you did not then do not feel too badly. I will be giving you many more opportunities to improve.

Today is the first of one of those opportunities because I am now going to give you another set of questions to answer. These will form parts of a typical question on enzymes and guess what you will be asked to use information presented in a table.

Question

Starch can be digested to give glucose. The reaction is catalysed by the enzyme amylase.

a) 'Polysaccharide' is the term used to describe starch. What term is used to describe glucose?

b) For their SBA laboratory exercise students were asked to investigate the effect of increasing the concentration of the enzyme amylase on the rate of this reaction.

The concentration of the starch was kept constant. The temperature was kept constant at 40ºC. The students were asked to use six different concentrations of the enzyme. The time taken for the starch to be completely digested at each concentration was measured. The results obtained by the students were collected and averaged. The averaged results are shown in table A.

i) Suggest a suitable aim for this experiment.

ii) Suggest a suitable title for the table that is given.

iii) Plot a graph of the results.

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

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

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

e) The students repeated the experiment at 20ºC and 80ºC.

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.

Have fun! Meet me at the next step next week!

Fathers prepare their sons for the start of Fathers' and Boys' Day under the theme 'Empowering Our Boys' at Mico Practising Primary and Junior High School recently. - Ian Allen/Staff Photographer