F4 Biology WS 10 ans

4 Enzyme and metabolism IV

WS 10

M.C.

1	2	3	4	5	6
A	B	A	A	B	C

Q.7

(a)    Enzyme is specific in action (1)

because it has unique active site to bind with substrates with specific shapes (1)                           

/ Enzyme can be reused (1)

because it remains unchanged after reaction (1) (Any ONE or other reasonable answers)               2

(b)    (i)     Chemical X has inhibitory effect on the synthesis of substance U (1).

                From the graph, the presence chemical X reduces the amount of substance U formation

                at different time (1).                                                                                                                2

        (ii)    Chemical X inhibits the formation of U, so that it can inhibit protein synthesis

                and even the growth of bacteria (1).                                                                                        1

Q.9

(a)    All the starch had been broken down.                                                                                   1

(b)    At 25 °C, more collisions occurred between the amylase and the starch molecules

        / molecules moved faster / molecules had more kinetic energy / enzymes worked faster.    1

(c)    Enzymes work on specific substrate only.

        / Only starch fits into the active site of amylase.                                                                    1

Q.11

(a)    The biological washing powder contains lipase (1),

        which break down the fat stain into fatty acid and glycerol (1).

        Fatty acid and glycerol can dissolve in water (1), and are removed from the skirts .                       3

(b)    The washing powder works better / is more efficient at higher temperature.                                    1

(c)    Marking criteria:                                                                                                              Max. 5

        - the control variable should be constant. (max. 2 marks)

        - choose the temperature at which the washing powder has the highest efficiency. (1 mark)

        - How to measure and interpret the results (2 marks)

        - Use different temperature to repeat the investigation (1 mark)

        For example:

        - Use two identical skirts with identical stains (1)

        - Put the skirts respectively into same volume of washing solutions containing

         same amounts of washing powder (1) / into washing solutions with same concentration

        - Washing time should be the same (1)                                                                            max. 2

        - The washing temperature should be maintained at 50^oC (1)

        - Compare the size / the intensity of the stains (1);

The higher the efficiency, the smaller / the lighter the stain is (1)

        - Use different water temperature to repeat the investigation, so as to study

         if the temperature affect the efficiency of different washing powders (1)                     max. 5 for all