A-level set practicals – dissection and microscopy of a plant stem
Resource
This resource supports the use of practicals across various A-level biology 2015 specifications for England (OCR, AQA, Edexcel and Eduqas).
‘Microscopy of a plant stem’ allows students to go from the plant on the desk, to observing a stained specimen under the microscope in less than 4 minutes (as shown in the image above). The viewed specimen clearly shows the location of vascular bundles and the xylem, phloem and sclerenchyma or collenchyma.
The use of the stain toluidine blue provides a colour difference between lignified and non-lignified cell walls, clearly highlighting specialised cells and one adaptation they have.
This experiment provides a quick and eye-catching way to teach about the vascular tissue in plants and the structure of plant stems. It provides students with the opportunity to develop (and demonstrate) their scientific drawing skills as well as their use of a light microscope and eye-piece graticule.
Materials include:
- Tested materials to support the A-level practical endorsement (CPAC)
- Support materials for teachers and technicians
- Student worksheet to help provide evidence for meeting the practical skills requirements
- Student revision materials to help prepare for exams
Support materials for other key practicals in A-level specifications can be found in the A-level set practicals collection.
Your FAQs Answered
Q: Besides celery, what other plants can I use?
A: You can use any stem really but you should consider the size and hardness of the stem. Asparagus works well as you can see the different pattern of vessels seen in monocots. Mint is good to use as it has a square stem but it can be fiddly to cut a thin slice. It is worth noting that a lot of flower stems are quite hard to slice.
Q: My stem is very dark after staining. What can I do about this?
A: You can dilute the stain. Some stems take up the stain better than others. It is worth trialling the stem and stain before using with your students.
What have other teachers and technicians said about this resource?
"This is a great practical for A Level for the plant transport topic. It allows students to meet the dissection and microscopy PAG in a short space of time and take more ownership of the microscopy in that they have produced their own stained slide of vascular tissue. They can get some great photos using their mobiles down the microscope and with the blue/green purple colour it is quite a 'wow that's great' moment. It is also useful in getting them to realise how think specimens need to be to try and get a monolayer of cells and to appreciate differential staining - great skills. I think this is a must at A level."