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Independent variables that may affect the rate of growth and reproduction…
Independent variables that may affect the rate of growth and reproduction of euglena
pH level of growth medium
How will it be measured
Utilising meters or other tools provided by the school (e.g. digital meters or analog testers)
Safety concerns
The usage of chemicals to alter the pH of each group replicate raises concerns, as potential bodily harm can be done if mishandled. Therefore, extra care and focus should be used when applying described chemicals.
How will it be controlled
A control group replicate will occur, with the
How can it be modified/changed?
Should this independent variable be chosen as the main focal point, the pH of the growth medium can be modified through the addition of alkaline and acidic chemicals in the growth medium of each replicate
Other concerns
N/A
Temperature
How will it be measured?
Thermometer
How can it be modified/changed?
Regulated environment (e.g. fridge or any other tools provided by the school)
How will it be controlled?
Various different temperatures will be utilised to see changes of growth, with a controlled temperature of 25.5 degrees celsius (room temperature). All other potential independent variables will remain constant should this factor be observed.
Safety concerns
Possible harm can be inflicted on one should they carelessly measure warmer temperatures
Other concerns
Unclear as to how a warm temperature can be regulated and remain constant
Light intensity
How will it be measured?
Use phone lux-meter
How will it be controlled?
A control group will be made and defined as average outdoor light, with each replicate being placed outside to simulate real growth environments.
Safety concerns
N/A
How can it be modified/changed?
Either electronic lights of varying intensity (voltage) will be used, or lighting environments available in the school (e.g. cupboards, window sills and other lights)
Other concerns
Are provided tools available which can control and make the varied light constant at all times?
Salinity of growth medium
How will it be measured?
Measuring amount of salt being added to each sample
How will it be controlled?
Each sample will have varying levels of salinity to monitor how salinity affects euglena's rate of growth. A sample will remain as a control with no additional water being added to it. All other potential independent variables will remain constant should this factor be observed.
Safety concerns
N/A
How can it be modified/changed?
Varying levels of salt will be used in each sample
Other concerns
N/A
Colour of light
How will it be measured?
This potential independent variable would not have to be measured per say, as the wavelength of the manipulated or produced light would remain constant and would correlate with wavelength groups as per the visible light spectrum. Rather, the change of absorption rate on every collection date will be the variable that is changed as a result of the change of colour.
How will it be controlled?
A controlled replicate will be present in the experiment in the form of a regular replicate affected by normal light. This means that this control will not be interfered with by cellophane or by any artifically coloured light source.
Safety concerns
N/A
How can it be modified/changed?
This potential independent variable can be modified through two possible alterations; that being wrapping each bottle in different coloured cellophane dependent on the replicate group, or having different coloured light bulbs.
Other concerns
N/A