IB Biology HL: Internal Assessment Lab Format
Please do not complete sections out of order (like attaching graphs at the end)
All IAs must be submitted to turnitin.com for plagiarism review
The following titles and subtitles should be used for your lab report.
Defining the problem
Enzymes are molecules in the body that increase the speed of reactions. They help carry out chemical reactions that are necessary for sustaining life.
Enzymes must be able to catalyze several reactions at once. They can only bind to a specific substrate in order to initiate the chemical reaction.
The rate at which the enzyme work depends on several factors, one being substrate and enzyme concentration.
The enzyme in this experiment is called catalase; it is involved in the process of breaking down hydrogen peroxide. Hydrogen peroxide is toxic to the body and has the ability to kill cells in the absence of catalase.
Hydrogen peroxide is the substrate for catalase, so it is important to determine the optimal concentration of hydrogen peroxide for these reactions to occur in the human body.
The evidence of personal engagement with the exploration is clear with significant independent thinking, initiative or creativity.
The justification given for choosing the research question and/or the topic under investigation demonstrates personal significance, interest or curiosity.
Research Question –
Enzymatic reactions: Investigating the effect of substrate concentration on the rate of the decomposition reaction of hydrogen peroxide.
make it clear what you are investigating
The reader should be able to deduce the point of the investigation from this sentence alone.
e.g. “Osmosis: investigating the effect of solute concentration on the weight of potato discs, when submerged in a range of concentrations of salt solution for 2 hours”.
Hypothesis –
The rate of reaction will be the quickest at the highest concentration of hydrogen peroxide, 30ml, as increasing substrate concentration (hydrogen peroxide) will allow for more active sites for the enzyme (catalase) to bind to.
make your prediction & then give a logical supported rationale
background information is required
remember to cite your sources using APA
Variables – chart identifying Independent, Dependent, & Controlled Variables
Variables
Units
Uncertainties
Independent Variable
Concentration of hydrogen peroxide
mL
+/- 1
Dependent Variable
Rate of enzymatic reaction, as measured by the rate of the filter paper.
cm/s
Controlled Variables
Units
Possible effect(s) on results
Method for Control
Temperature
Celsius
A higher temperature could have increased the rate of reaction.
All trials were conducted under room temperature.
Protocol Diagram – draw & label a diagram which best shows the protocol you used –
most likely in the form of a flow chart
Photograph of Lab Setup – annotate this to show how variables were instituted, especially the controls. Do not just label equipment.
Materials –
Hydrogen Peroxide
Catalase
Medicine cups (15)
Water
Graduated cylinder
Timer
Filter Paper
Hole puncher
Procedure –
15 medicine cups were set up in 5 rows of 3. Each row represented a different trial.
A hole punch was used to make holes in filter paper.
Water, hydrogen peroxide, and catalase were obtained. The proper amount of hydrogen peroxide and water was poured into each medicine cup, as shown below:
Trial Number (Each trial had 3 medicine cups)
Hydrogen Peroxide
Water
Trial 1
0
30
Trial 2
6
24
Trial 3
12
18
Trial 4
24
6
Trial 5
30
0
Forceps were used to take a singular filter paper circle. The circle was dipped in catalase for five seconds.
The filter paper circle was placed on the top of each solution. Once the filter paper hit the bottom of the medicine cup, the timer was started.
The time, in seconds, it took the filter paper to reach the surface was recorded.
The distance over time was calculated to determine the overall rate of reaction.
write in bulleted form, passive voice, and past tense….be sure to emphasize
how many times each data set is being repeated (3 is minimum, 5 is ideal, 10 if you are doing a t-test )
Include details of how to measure your independent and dependent variables.
Give precise details of values, units and equipment
Make sure you are collecting enough data – how large does your sample size need to be?
How many times will you repeat your investigation to ensure reliable results?
Data Collection
Raw Data Table –
Make sure this is raw data only.
Data table design & clarity is important.
A title should be given (Raw Data Table is not a data table title, it is a lab report section title)
Make sure that all columns, etc. are properly headed & units are given.
Forgetting one unit or misidentifying one unit is enough to drop your score in this section.
Do not “split” a data table (putting part of a table on one page and finishing it on another). If you absolutely have to split a table (due to quantity of data), make sure that you re-do the title and all column headings. Uncertainties* can be given within column headings for equipment precision and as footnotes beneath data tables for other types of uncertainties.
Trial
Amount of Hydrogen Peroxide Added (mL)
Amount of Water Added (mL)
Percentage of Hydrogen Peroxide
Time it Took the Filter Paper to Rise (sec)
Distance Traveled (cm)
1
0
30
0%
N/A
N/A
1
0
30
0%
N/A
N/A
1
0
30
0%
N/A
N/A
2
6
24
20%
7.87
3
2
6
24
20%
6.98
3
2
6
24
20%
7.23
3
3
12
18
67%
4.98
3
3
12
18
67%
5.04
3
3
12
18
67%
6.34
3
4
24
6
80%
4.04
3
4
24
6
80%
3.92
3
4
24
6
80%
2.16
3
5
30
0
100%
2.06
3
5
30
0
100%
1.87
3
5
30
0
100%
1.59
3
Data Processing & Presentation
Trial
Average Time (s)
Rate of Reaction (cm/s)
Average Rate of Reaction (cm/s)
1
N/A
N/A
N/A
1
N/A
1
N/A
2
7.36
2.62
2.45
2
2.33
2
2.41
3
5.45
1.66
1.82
3
1.68
3
2.11
4
3.37
1.35
1.13
4
1.31
4
0.72
5
1.84
0.69
3.53
5
0.62
5
0.53
Overview – this is a short paragraph section that gives an overview of how and why you decided to process and present the data in the form that shows up later in this section.
Sample Calculation – neatly lay out and explain one example only of any one type of manipulation that was done to the raw data to help make it more useful for interpretation. Make sure you have checked all your calculations to avoid any silly mistakes.
Presentation – this is typically one or more data tables (of your now processed data) and one or more graphs of this processed data. Once again, the design & clarity of data table(s) is important and the quality of graphs is also very important. Give careful consideration to the choice of graph style(s) that you choose to do. Make sure that you follow good standard rules for doing graphs (valid title, axis’ labeled including units, etc.) Weak experimental design can sometimes limit you to pie graphs and/or bar graphs; avoid this by good experimental design in which you have a quantitative independent variable (with well chosen values) as well as a quantitative dependent variable.
Solute Concentration
(%) (+/- 0.5%)
Repeat
Weight Change
(g)
% Weight Change
(g) (+/- 1%)
Mean % Change
(+/- 1%)
SD from mean (usually)
0
1
2
3
Conclusion & Evaluation
Conclusion – This is a paragraph section in which you get a chance to discuss the results of your experiment. Start by addressing whether your data seem to support or refute your hypothesis. This should be discussed and not just stated. Specifically refer to your graphs to give support to this discussion. Avoid the use of the word “proof” or “proves” within your conclusion, as your data will not prove anything.
Interpret your results, based on the data collected and with reference to your hypothesis or background information.
What (if any) general trends do you observe? What do they suggest?
Are there any anomalous (unusual) results? What might be their significance?
Does the data you collected support your hypothesis? Why/ Why not?
What does your data suggest about the outcome of your research question?
Do other sources of information or investigations support your findings? (Cite your sources!!)
How could you develop this investigation for further study?
Evaluation:
Evaluating the procedure – this paragraph section discusses how well your experimental design helped answer your experimental question. What worked well (and why) and what did not work well (and why). This must be a worthwhile evaluation of the method chosen, rather than a superficial commentary on poor lab techniques and sloppy work. “I should measure more accurately” is a problem with your practical skills, rather than the method of investigation.
Did you record any anomalies in your practical work? How did they affect your results and what did you do to minimize their adverse effects?
What weaknesses were present in the method chosen for the investigation and how could they have affected the outcome?
Did anything occur during the investigation to comprise the reliability of your results?
Improving the investigation – this section should be used for two purposes.
what minor improvements could be made to the design features that you just mentioned in the previous section that would perhaps lead to better results next time
what suggestions do you have for other possible experimental designs that may work better for answering this question
*Some notes on uncertainties
Sometimes there are systematic or random errors that decrease your data’s value. All measurements (columns) should include a Margin of Error at the top under the unit.
In DC, when using a device to measure there is an uncertainty that is a direct consequence of the instrument used. If, for example, when measuring the length of a leaf with a ruler the value recorded is 5.4 cm, there is an uncertainty in this value recorded due to the precision of the ruler. If the smallest division in the ruler is 0.1 cm, the length of the leave can be expressed as 5. 4 cm + – 0.1 cm. This means that the real length of the leave is a value between 5.3 cm and 5.5 cm. In DC the units and uncertainties need to be stated in the headings of the table.
Describe simply any uncertainties under the data table or after the data interpretation section. This is the uncertainty of the data and MUST be included to obtain a complete.
1
1
na
2
1
na
3
1
na
4
2
5.76
5
2
5.6
6
2
5.7
7
3
4.27
8
3
4.1
9
3
4.3
10
4
3.4
11
4
3.16
12
4
3.28
13
5
0.76
14
5
1.02
15
5
0.64
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