Hodan Hashi October 29, 2014

What is the Concentration of dissolved Solids in a potato cell?

DESIGN – Aspect 1: Defining the problem & selecting variables

Research Question:
How does the concentration of salt solution affect the mass of the potatoes.
Background Information:
Try to include known values / expected results from literature
If you are going to include diagrams make sure you give them a fig # & descriptive title.

Hypothesis:

Table 1: Variables Selected for this Experiment
| |Units |Range |
|Independent Variable | | | |
|Dependent Variable | | | |
| |
|Control Variables |Units |Possible effect on results |
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Aspect 2: Controlling the Variables & Aspect 3: Developing a Method for Collection of Data

Describes a method that allows for the effective control of variables.
a. Explicitly states how the independent variable will be changed, with values.
b. Explicitly states how control variables are fixed, with values where appropriate.
c. Selects appropriate apparatus. NOTE: Students must at all times indicate that they are aware of safety issues & requirements when planning for labs. It is a good idea to include a completed risk assessment form (available on first class) Pg 3 of THE IB Biology Lab Guide

Describes a method that allows for the collection of sufficient relevant data.
a. Range of data is effective for the task.
b. Plans to collect between 5 and 10 data points.
c. Plans to repeat data collection or to increase the number of readings, whichever is more appropriate. Pg 4 of THE IB Biology Lab Guide

Table 2: Method for Controlling Variables
|Control Variables | Method for Control |
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Materials:

Method:
1.
2.
3.
etc.

Diagram 1: Experiment Setup fully labelled diagram or photograph

DATA COLLECTION & PROCESSING - Aspect 1: Recording Raw Data & Aspect 2: Processing Raw Data

Records appropriate quantitative raw data, including units and uncertainties where relevant.
a. Headings and units are included and are correct.
b. Where relevant uncertainties are included in table headings.
c. Uncertainties are consistent (same number of significant figures) with the raw data.
d. There is no variation in the precision of the raw data eg significant figures are all the same & they reflect the precision of the instrument. Pg 5 of THE IB Biology Lab Guide

Processes the quantitative raw data correctly.
a. Processes raw data, if necessary, into a form suitable for graphical representation eg combing & manipulating the data
b. Plots a suitable ‘best-fit’ line graph.
c. Recording & processing of data may be shown in the one table BUT they must be clearly distinguishable (see e.g. of table above where the processing part of the table was left unshaded).
d. Sample calculations must be included eg Equation 1: Standard Deviation Calculation . Pg 6 of THE IB Biology Lab Guide

Table 3: Title (should include the independent and dependent variables)

Sample Calculations
Equation 1:

Aspect 3: Presenting Processed Data

Presents processed data appropriately and, where relevant, includes errors and uncertainties.
a. If you are comparing a relationship between parameters then a graph will be most appropriate as it provides a visual representation of the data
a. Both axes labelled and include the correct units
b. At least 70% of the graph paper is used.
c. Points are plotted accurately
d. Error bars are drawn for at least one variable or line of best fit is included. Pg 7 of THE IB Biology Lab Guide

Graph 1: Title (should include the independent and dependent variables)

Graph 2 etc

CONCLUSION & EVALUATION Aspect 1: Concluding
States a conclusion, with justification, based on a reasonable interpretation of the data.
a. The relationship between the variables is correctly stated.
b. Students must justify their conclusion and note any systematic or unforeseen random uncertainties (anomalies).
c. Results are calculated and compared with referenced accepted values.
d. The percentage difference between calculated and accepted values is stated and compared to uncertainty of calculated value. Pg 11 of THE IB Biology Lab Guide

Aspect 2: Evaluating Procedures & Aspect 3: Improving the Investigation

Evaluates weaknesses and limitations.
a. Comments on the overall ‘quality’ of the procedure used and data collected.
b. Significant weaknesses and limitations in the process, equipment used and management of time are identified.
c. Has some appreciation of the significance of each weakness. Pg 12 of THE IB Biology Lab Guide

Suggests realistic improvements in respect of identified weaknesses and limitations.
a. Weaknesses and limitations identified in aspect 2 are addressed.
b. Realistic improvements are suggested.
c. Suggestions state exactly what should be done to reduce random uncertainties or to improve the quality of the data.
d. Suggestions on how to remove systematic uncertainties, if present, are made. Pg 13 of THE IB Biology Lab Guide

Table: Errors, Limitations, Weaknesses and Improvements
|Systematic Errors (if present) |Significance, Effect and Direction |Improvement |
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|Random Errors |Significance and Effect |Improvement |
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|Weaknesses and Limitations |Significance and Effect |Improvement |
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Bibliography