Back
Home
3.6 identify data sources, plan and choose equipment or resources to perform a first-hand investigation to gather data to determine the effect of light intensity and temperature on gas production in a suitable pond weed
identify data sources, plan and choose equipment or resources to perform a first-hand investigation to gather data to determine the effect of light intensity and temperature on gas production in a suitable pond weed
- Identify your data sources by determining the type of data that needs to be collected and explain the qualitative and quantitative analysis that will be required for this data to be useful. Will you measure the light intensity quantitatively or just move the specimen away from the light and describe the light as greater or lesser?
- Plan your experiment to recognise the variables that need to be kept constant and demonstrate the use of a control. Variables to consider include temperature, volume of the water and quantity of pondweed.
- Choose equipment by identifying technology that could be used during the investigation and determine its suitability.
- Perform the investigation by carrying out the planned procedure recognising any modification that need to be made.
- Gather the first hand information by measuring, observing and recording results and carry out repeat trials if necessary.
Sample method
For light intensity, set up several test tubes with fresh water and a suitable pondweed. Adding the same amount of NaHCO3 to each tube can ensure a good supply of CO2. Different light intensities can be produced by placing the test tubes at different distances from the same light source (a fluorescent desk lamp for example). Oxygen evolution can be determined using an oxygen sensitive probe and a data logger over time or bubbles of gas evolved per minute can be counted over time.