These practical protocols are designed for students doing an Extended Project Qualification, Advanced Higher investigation, or IB investigation in biology.
They are linked to our Medicinal plants – conifer trees & cancer project starter.
Possible investigations: Plant growth inhibition
- Compare the inhibitory effects on plant growth of extracts from cones or needles
- Collect conifer needles from the woodland floor and compare the inhibitory effects on plant growth of old needle extract against new needle extract
- Compare the inhibitory effects on plant growth of extracts from old and immature cones
- Compare growth inhibition using different plant seeds e.g. plants commonly found on woodland floors
Possible investigations: Microbial inhibition
- Investigate the inhibitory effects of the conifer extracts on microbial growth, e.g. compare extracts from different conifer species or from new and old cones/needles
- Investigate the effect of an extract on different microbes
Protocol: Producing an extract from conifer needles
Select the conifer which you plan to investigate, e.g. pine, cypress, spruce or yew. Eileen Smith’s work (see above) may give you some useful research ideas to test.
You will need to source your plant material from an appropriate place, taking into consideration the environmental effects of taking plant material from the wild. You will also need to reflect on how to can be sure that you have correctly identified the species you are testing.
- Take 2.5g of needles or cones and grind in a mortal and pestle with 30cm3 of sterile distilled water
- Filter the extract through muslin and pour into a clean labelled bottle
Protocol: Investigating effects of conifer extracts on seedling growth
- Pre-label petri-dishes with each conifer extract to be used (do replicates of each extract)
- Place filter paper into petri-dish base and moisten with 1ml of sterile water
- Weigh out 0.3g of cress seeds and scatter evenly onto pre-labelled petri-dishes
- Water each dish with 2cm3 of conifer extract or sterile water (control)
- Place under light bank
- Water daily with 1cm3 of extract or sterile water
- Each day record % germination of seeds and from day 2 onwards measure average root and shoot length
- Plot results showing % inhibition of germination, root and shoot growth
Protocol: Investigating the effects of confider extracts on bacteria
To do this, you will prepare agar plates suitable for growing lawns of bacteria, place different plant extracts in wells on the plates and measure any zone of inhibition.
The methods for this activity can be found in the project starter ‘Antimicrobials’ ( http://www.saps.org.uk/students/projects/148-investigating-antimicrobials ) and further information about the algae and culture medium can be found on the SAPS web-site in our algal balls resource (http://www.saps.org.uk/secondary/teaching-resources/235)