Biology Practical Paper
1.Experiment interpretation:
a. Draw table (at least 2 row + heading + unit)
b. State conclusion: based on the purpose of the experiment
c. Identify variable:
i.
Independent variable
ii.
Dependent variable: use to make comparison
d. Control variable: Minimize errors, make comparison more accurate (ones mentioned)
i.
*Same mass
ii.
Same size
iii.
Same surface area
iv.
*Same volume
v.
Same concentration
vi.
Same PH
vii.
viii.
*Same temperature (room, liquid)
*Same time
ix.
Plant: Same species, age, humidity, wind speed, light intensity (distance),
number of leaves, size of leave, number of stomata
x.
Animal: Same gender, age, body mass
e. Understand purpose of the control group: to find out that XXX has no effect
f. Error: Those controlled variables that are not mentioned in the experiment
g. Improvements:
i.
Repeat the experiments and calculate the average
ii.
Test on more intermediate independent variables
iii.
Extend the range of independent variables used
iv.
Wait for longer time
v.
Use warmer solution
2.Food test:
a. Extracting juice by grind and squeeze it
b. Reducing sugar: Benedict solution + heat, blue to brick red
c. Starch: Iodine solution, yellow brown to blue black
d. Protein: Biuret test, blue to purple
e. Lipid: Emulsion test (ethanol+water+stir), colorless to milky white color
f. Vitamin C: DCPIP, blue to colorless
3.Experiment data interpretation:
a. Plotting graph:
i.
line graph (connect point by point, need key if there are two lines we need to
draw)
ii.
Bar chart (equal width for each bar, equal width in between bars)
iii.
Histogram
b. Evaluate the data: anomalous data are data that don’t follow the trend
c. Predict more data: find out gradient and intercept
d. Conclusion of data - relationship of IV and DV:
i.
Describe if it is proportional / exponential
ii.
Describe the gradient (steepness)
e. Compare the data: Similarity & difference about the value and trend + Prove with data
4.Compare two photos
a. Size (Big & Small)
i.
Length of stem (Long & Short)
b. Shape (flat & round)
c. Outline (smooth and wavy & sharp and serrated锯齿状的/ spike有刺的)
d. Details:
i.
Color (light & dark)
ii.
Number of hairs
5.Experiment planning question:
a. Independent variable: Use 5 sets of independent variable
b. Dependent variable: Measure xxx
c. Control variable x 3: Keep xxx the same
d. Method:
i.
Way to obtain and maintain independent variable
ii.
Way to conduct the experiment
iii.
Way to measure the dependent variable
e. Reliability: Do the experiment for 3 times and get the average
f. Safety:
i.
Wear goggles and gloves
ii.
keep blade away from body when cutting
TIPS:
1) Independent variables:
a) Different temperature is used (degree)
b) Different concentration is used (mol/dm^3)
c) Different light intensity is used
d) Different wind speed
e) Different humidity
f) Different CO2
2) Way to obtain:
a) Temperature: Thermostatically controlled water bath
b) Concentration: Number of solute + (10 - Number of water)
c) Light intensity: Distance between light and plant
d) Wind speed: Use a fan/ not use a fan
e) Humidity: Use a plastic bag/ not use a plastic bag
f) CO2: Use different concentrations of sodium hydrogen carbonate solution
3) Dependent variable to measure:
a) Color - Colorimeter
b) Distance - Ruler
c) Volume of gas - Syringe
d) Volume of liquid - Measuring cylinder
e) Mass - Digital balance
f) Temperature - Thermometer (takes time to measure the water)
g) Time - Stopwatch
6.Drawing
a. Check:
i.
S - size : x2 or x1.5
ii.
O - Outline : solid single outline
iii.
L - Labels: 2+ labels
iv.
D - Detail: all what you see!
7.Calculation
a. Measurement: in mm
b. Calculation: Magnification = image length / actual length
TIPS:
* When measuring time take for positive test, taking samples are intervals
* For celery stalk, slice the end off the celery before immersion
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