Ecosystems
A comparison and evaluation of three student practicals
GTAC have prepared controlled experiments to support delivery of Unit 3 Outcome 2.
Students should be provided with a variety of opportunities to demonstrate satisfactory completion of the outcome and you should design a SAC task to assess student skills and knowledge. Tasks developed for students to demonstrate satisfactory completion of the outcome and for the SAC task should be authenticated. We recommend that you develop a rubric that shows students how they will be assessed for this outcome.
Use this document to consider the key skills and knowledge that you will use for students to demonstrate satisfactory completion of the outcome and for your SAC task
Preparing for Unit 3 Outcome 2 - using a comparison of controlled experiments task
GTAC have developed a number of resources to support you to develop your approach to running Unit 3 outcome 2.
Using a model of cellular respiration and photosynthesis to make predictions and design experiments:
Students view animations to develop word equations as a model for photosynthesis and respiration. They use their models to design experiments and make predictions about factors that can affect the rate of these biochemical pathways.
Student study tool
This study aid has been designed to support students to carry out a qualitative analysis of quantitative data. Students can use the study aid to help learn skills required to analyse and evaluate data and investigation methods. Solutions to quations designed to help students refine their skills are also provided.
Student study tool: Performing a qualitative analysis of quantitative data
Student study tool: Performing a qualitative analysis of quantitative data with suggested responses
Practical activities: Using leaf discs to investigate the rate of photosynthesis
In this series of activities, students practice skills in carrying out a controlled experiment methodology to investigate the effect of light and carbon dioxide on the rate of photosynthesis. The method used in these experiment uses leaf discs to measure rate of photosynthesis. There are three parts to this resource.
- Part A; Students practice the leaf disc method to interrogate the method and learn how to generate, record and analyse their primary data.
- Part B: Students develop a hypothesis and a method for measuring effect of light colour (different wavelengths of light) on photosynthesis. They generate, record and analyse data.
- Part C: Students develop a hypothesis and a method for measuring effect of carbon dioxide concentration on the rate of photosynthesis. They generate, record and analyse data.
Part A and Part B are similar so they can be given to different groups of students or you can alternate the task that you provide annually. This task takes some time to carry out so we suggest that you can discuss repeatability and reproducibility by pooling class results, or providing a set of results to students that they add their data to. If doing this it provides a good opportunity to identify errors and outliers and analyse the data qualitatively.
Recorded sample results are provided for students to use to generate data should they be required.
Leaf disc practical activities Advice to teachers and lab techs
Student logbook – using leaf discs to investigate rate of photosynthesis
Practical activities: Using yeast suspensions to measure effect of glucose concentration on rate of cellular respiration
Students are provided a method to use. They analyse the method, generate primary data, organise the data in tables and graphs, and analyse and evaluate their data.
Advice to teachers and lab techs
Practical activities: Using yeast suspended in agar balls to measure the effect of temperature on the rate of cellular respiration
Students are provided a method to use. They analyse the method, generate primary data, organise the data in tables and graphs, and analyse and evaluate their data.
Student logbook – coming soon
Advice to teachers – coming soon