Download Year 10 Practical Assessment Skills – Lesson 2 Conclusions

Year 10 Practical Assessment Skills –
Lesson 2 Conclusions
Aim: to be able to make conclusions by using
results and graphs
Must: make simple conclusions using “er”
statements
Should: be able to identify patterns in results
Could: identify errors in results and account for
them, suggesting possible improvements
Say what you have found out
Using “er” statements
• After completing an experiment it is important
to say what you have found out.
• If possible it is best to use an ER statement.
• Change the following to an ER statement.
• A block of wood will burn quicker if it is cut up
into small bits.
• The smaller the wood the quicker it
burns
GCSE Biology Coursework
Osmosis Practical Example
Background Science
Osmosis is the diffusion of water molecules across a
partially permeable membrane, from a region of high
concentration to a region of low concentration.
The partially permeable membrane contains a series of
small holes, allowing only water molecules to pass
through. For example glucose molecules are too big to
fit through the membrane. As there are a greater
number of water molecules on one side, there is a
steady net flow into the other side with fewer water
molecules, i.e. into the stronger solution
GCSE Biology Coursework
Osmosis Practical Example
Factors which could have an affect on osmosis in plant cells.
• Surface area of the potato plug – It may make the process of
osmosis slower, if a large potato plug is used in the experiment.
• Sucrose concentration – Osmosis may be quicker if the
concentration is stronger.
• Age of potato – Osmosis may be more efficient in newer potatoes
than older ones.
• Variety of potato – Osmosis is likely to differ if a different variety of
potato cells are used.
• Temperature – If the temperature is hotter, this may speed up the
process of osmosis.
• Mass of the plug – Again, it may slow down osmosis if the potato
plug is many cells thick compared to only a few cells thick.
Osmosis Practical Results: Set 1
Sucrose
Concentration
Mass
Before (g)
1M
0.8M
0.6M
0.4M
0.2M
0M
2.19
2.08
1.90
2.06
2.21
2.49
Mass
Mass
After (g) Change (g)
1.91
1.93
1.81
2.01
2.18
2.61
▼0.28
▼0.15
▼0.09
▼0.05
▼0.03
▲0.12
%
Mass
Change
▼12.79
▼7.21
▼4.74
▼2.43
▼1.36
▲4.82
Osmosis Practical Results: Set 2
Sucrose
Concentration
Mass
Before (g)
Mass
After (g)
Mass
Change (g)
% Mass
Change
1M
2.17
1.95
▼0.22
▼10.14
0.8M
2.30
2.16
▼0.14
▼6.09
0.6M
2.12
2.04
▼0.08
▼3.77
0.4M
1.99
1.96
▼0.03
▼1.51
0.2M
1.89
2.00
▲0.11
▲5.82
0M
2.18
2.41
▲0.23
▲10.55
Osmosis Practical Results: Set 3
Sucrose
Mass
Mas
Mass
Concentration Before (g) s After (g) Change (g)
%
Mass
Change
1M
2.19
2.00
▼0.19
▼8.68
0.8M
2.18
2.06
▼0.12
▼5.50
0.6M
2.31
2.22
▼0.09
▼3.90
0.4M
1.99
1.95
▼0.04
▼2.01
0.2M
2.29
3.00
▲0.01
▲0.44
0M
2.16
2.41
▲0.25
▲11.57
Osmosis Practical Results: Averages
Sucrose
Concentration
Average Mass
Change (g)
Average % Mass
Change
1M
▼0.23
▼10.54
0.8M
▼0.14
▼6.27
0.6M
▼0.09
▼4.14
0.4M
▼0.04
▼1.98
0.2M
▲0.03
▲1.63
0M
▲0.20
▲8.98
% Mass Change
Graph Showing % Mass Change when
Potato are placed in Sucrose Solution
Sucrose Concentration (M)
GCSE Biology Coursework
Osmosis Practical Example
TASK: From the information you have now be given on
the osmosis practical write a conclusion for the
experiment.
Help
• Remember you are trying to say what you have found
out from the experiment or analysing the data.
• If possible it is best to use an ER statement.
Key “er” Words (examples);
“bigger”; smaller; “faster”; “slower”; “heavier”; “lighter”
Other Practical Examples
On the following slides try to make a conclusion
and if possible identify any errors in the data.
Rolling a car down a ramp and measuring speed at a
fixed point.
• How can the data be made more reliable?
• Are there any anomalies?
• What variables need to be controlled?
Height of ramp (cm)
Speed (m/s)
5
1.2
10
1.5
15
0.7
20
2.1
25
2.4
30
2.7
35
3.0
40
3.3
Speeds reached
3.5
3
2.5
2
1.5
1
0.5
0
• How can the results be showed more clearly?
• What other improvements are needed?
5 cm
10cm
15cm
20cm
25cm
30cm
35cm
40cm
Conclusion
• “The speed of the car always increases if the
ramp is made higher”
Write a better analysis!
Try writing an evaluation with www and ebi.
Examples of conclusions
• Example 1
My results show me that some rocks fizz and some do not when acid is
added.
Hydrochloric acid made calcium carbonate fizz, sulphuric acid made
sodium carbonate fizz and copper carbonate made hydrochloric acid fizz.
Fizzing also happened between zinc carbonate and nitric acid and iron
carbonate and hydrochloric acid. None of the other rocks fizzed. The
reason for this is that there is a reaction between some types of minerals
that might be in rocks and acids. You could use this as a test for some
minerals, but you could not tell which is which. The bubbles mean that a
gas is made in the reaction. The gases I know about are hydrogen, oxygen
and carbon dioxide, it could be one of these, but I would need to test
them.
Examples of conclusions
• Example 2
My results show me that fizzing only occurs with those
minerals that contain carbonate. The results also show that it
doesn’t matter what type of acid you use. I conclude that
carbonates react with acids to produce a fizz. You could use
acids to test whether rocks contain carbonates or not.
The fizz means that a gas is given off. This gas is probably
carbon dioxide, because it comes from a carbonate and the
names are similar. I could test and be sure by seeing if the gas
turns limewater milky.
To be completed
Conclusion 1 Strengths
Conclusion 1 Weaknesses
Conclusion 2 Strengths
Conclusion 2 Weaknesses