Answer: GempurPaper 3~Set 1- Blog version

The answer for the first sample extracted from SBP collection

~ Peperiksaan Akhir Tahun Tkt 4 2006. (Its Blog set...not the one which Bellatrixians answer for CNY break)


a)(i) Obs 1. At the distance of 20 cm the number of gas bubbles is 20

Obs 2. At the distance 60 cm the number of gas bubbles is 5

(ii) Inf 1 :
Photosynthesis process is high /at its maximum when light intensity is high.
Inf 2: Photosynthesis process is low when light intensity is low

(b)Time = 10 min
20cm =20
40 cm = 15
60 cm = 10
80 cm = 5

(c)(i)

Manipulated variable ;
Distance from the bulb
How to alter the manipulated variable:
Changing the distance from the menthol bulb

Responding variable :
The number of gas bubble realeased // rate of photosynthesis
How to determine responding variable:
Counting and record the number of gas bubbles released using stopwatch //
Calculating the rate of photosynthesis using Formula:

Fixed variable :
Time //Temperature of the water
How to maintain the fix variable:
Fixing time to be 10 minutes //Constant the temperature at 27 C

(d)(i) Criteria for hypothesis:
P1 : state the manipulated variable.
P2 : state the responding variable
R : relationship between P1 and P2

The closer the bulb to the aquatic plants // The higher the light intensity, the more gas bubbles are released

(ii)Able to draw a graph base on the criteria below:
· label axis-x and axis- y with correct unit
· constants scale
· all point have been transfer correctly
· smooth graph shape



(iii)
The lower the light intensity the lower rate of photosynthesis
Because the when distance from the bulb is decreased, chlorophyll absorbs less light energy for photosynthesis


(e) The rate of photosynthesis is decreased .......
because at high temperature (60°C),E: the plant enzymes are denatured.


(f)F1: When the temperature increases /0 C -30C, the rate of photosynthesis increases
F2 : when the temperature becomes optimum /30C -40C rate of photosynthesis maximum
F3: When the temperature increases more /40 C – 60C, the rate of photosynthesis will decrease

(g)Able to define photosynthesis operationally based on the criteria below
C1 : gas release
C2 : presence of light
C3 : presence of carbon dioxide and water

Photosynthesis is a process which green plants use carbon dioxide and water to release gas in the presence of light

(h)

QUESTION 2

Problem statement : How does pH affect the activity of yeast? //
What is the effect of pH on the activity of yeast?

Objective : To study / investigate the effect of pH on the activity of yeast.

Hypothesis : The activity of yeast is optimal in an acidic medium (Any possible hypothesis is accepted!)

Variables :
Manipulated variable : pH value
Responding variable : Height of the coloured liquid in the manometer
Controll ed variable : Volume of yeast suspension // temperature// light intensity

Apparatus & Materials : Yeast suspension ,coloured liquid, distilled water,hydrochloric acid solution, sodium hydroxide solution, pH paper. Boiling tubes, beakers, glass tubes, clips, rubber stoppers, rubber tubing, retort stand, manometer tubes, strings, measuring cylinders, stop watches.

Technique used : To measure and record the height of the coloured liquid in the manometer using a ruler.

Procedure :







Figure 1

1.Label five boiling tubes A, B, C, D and E.
2.Fill all the boiling tubes with 15 cm3 of yeast suspension. (controlled variables).
3.Add the following contents into boiling tubes A. B, C, D and E respectively.
(manipulated variable).
A : 4 drops of 0.1 mol dm-3 hydrochloric acid solution
B : 4 drops of 0.01 mol dm-3 hydrochloric acid solution
C : 4 drops of distilled water.
D : 4 drops of 0.01 mol dm-3 sodium hydroxide solution.
E : 4 drops of 0.1 mol dm-3 sodium hydroxide solution.
4. Shake the content in boiling tube A, B, C, D and E. Determine the pH of the solution using pH paper.
5. Set up five sets of apparatus as shown in Figure 1.
6. Start the stopwatch and observe the activity of the yeast. Then note the level of coloured liquid in the manometer after ten minutes. Record the height of the coloured liquid in the manometer. (responding variable)
7 Record the results in the table below.
8 Precaution: Ensure that apparatus set up is air tight

Presentation of data :


Conclusion : The activity of yeast is optimal in an acidic medium.