MATAPELAJARAN BIOLOGIQUESTION 1(20 MARKS)Answer all questionspH is one of the factor that affect enzymatic reaction. Most enzymes are effective in a narrow pH range only. The optimum pH is the particular pH at which the rate of reaction is fastest. Deviations from optimum pH will decrease the rate of reaction because the bonds maintaining the tertiary shape of enzyme are broken.

Effect of pH on the rate of enzyme reaction can be determine by using laboratory experiment. The aim of this experiment is to study the effect of pH on the activity of pepsin. You are provided with egg albumen suspension, 1% pepsin solution, dilute hydrochloric acid and dilute sodium hydroxide solution.

Based on diagram I, plan and carry out the experiment to study the effect of pH on the activity of pepsin.The steps of the experiment are as follow :1. Label three test tube as P, Q and R. 2. Place 5ml of egg albumen suspension and 1ml of pepsin solution into each test tube. 3. Add 5 drops of distilled water into test tube P by using dropper.4. Add 5 drops of dilute hydrochloric acid into test tube Q by using dropper. 5. Add 5 drops of dilute sodium hydroxide solution into test tube R by using dropper.6. Place all the three test tube into a water bath at 370C for 20 minutes.7. Record the appearance of contents in each test tube at the beginning and the end of experiment.8. Test the contents in each test tubes with pH paper.

Based on the experiment which has been carried out, answer the following questions.a) Construct a table and record your observation.

(3 marks)

b) State why all the test tubes must be immersed in a water bath that set as 370C?_____________________________________________________________________________________________________________________________________________________(1 mark)

c) Explain the changes of contents in each test tube.___________________________________________________________________________________________________________________________________________________________________________________________________________________________________(3 marks)

d) State a precaution step when handling this experiment._____________________________________________________________________________________________________________________________________________________(1 mark)

e) i) If the experiment for test tube Q is repeated by setting the temperature at 600C, predict the observation of the content in the test tube?_____________________________________________________________________________________________________________________________________________________(1 mark)

ii) Give two reasons for your answer in (e.i)._____________________________________________________________________________________________________________________________________________________(2 marks)

f) Based on this experiment, state the operational definition of enzyme.___________________________________________________________________________________________________________________________________________________________________________________________________________________________________(2 marks)

g) Based on this experiment, classify the list of apparatus and materials given._____________________________________________________________________________________________________________________________________________________(2 marks)

h) i. Another experiment is carried out to study the effect of 1% pepsin solution, 5% pepsin solution and 10% pepsin solution on the digestion of protein.

State the following variables:

Manipulated variable______________________________________________________________________________

Responding variable_______________________________________________________________________(2 marks)

ii. State the hypothesis for the experiment in (h)(i).___________________________________________________________________________________________________________________________________________________________________________________________________________________________________(3 marks)