Cell structure
The understanding of cell structure and function, the cell theory, is a unifying concept in biology. All living organisms have similarities as well as differences in relation to cell structure, cell biochemistry and cell function. A level students need to extend their knowledge and understanding of cell structure and function from Key Stage Four studies and be able to apply this understanding to a range of biological processes. The similarities and differences in the structure and ultra structure of prokaryotic and eukaryotic cells being key to developing understanding of a range of biological functions.
Students should be provided with a variety of practical opportunities to develop microscopy skills to support their understanding of cell structure. This should include an appreciation of using both magnification and resolution and also how differential staining helps to view different cell structures. Students should be provided with opportunities to use an eye piece graticule and stage micrometer and should be familiar with cellular images produced from different microscopes.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
The Cell *suitable for home teaching*
This is an extensive resource package, which includes the Wellcome Trust Big Picture magazine, referred to below in Secrets of cells. In addition there are several presentations which include some great images. These can be used as class presentations; one of the presentations is an activity where students have to identify the presented images (answers are provided). There is also a useful video on working with cells.
Bingo Games
This resource was designed for use with much younger students and consequently the vocabulary and meanings are way below the A level requirement. The concept of the activity, however, is a really useful one either as a diagnostic starter activity for this topic or as a revision activity.
The resource could be used in two ways. The teacher could amend the meanings and vocabulary on the bingo cards so that all required terms, such as the organelles, are included or students could work in groups and devise their own game, with appropriate terms. The class can then play each game to consolidate knowledge and understanding of terms and meanings.
A-level set practicals: dissection and microscopy of a plant stem
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.
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.
Simple extensions to the basic protocol would allow students to collect data in cell diameters of different specialised cells, or from different plant species very quickly. Student could also explore modifications to the protocol to try to get clearer images of the vascular tissue, thereby developing their skills of experimental design.
What's in a Cell? *suitable for home teaching*
This is an article from the Catalyst magazine. The article includes detailed electron micrographs of two Acinar cells from a pancreas, which would well on a white board/hand held device. Students could be asked to identify as many organelles as possible (with a rationale) and then compare this with the detailed key provided on the final page of the article.
The article also includes information on the endosymbionant theory; which could be used as a research extension activity for A level biologists to extend their knowledge and understanding beyond the required assessed content and also consider the wider idea of how biological theories are proposed, evidenced and accepted.
Seeing Inside Cells *suitable for home teaching*
This Catalyst article focuses on how various types of microscopes are used to investigate the cellular environment.
Students could be given this article as pre-reading for a lesson, they could be asked to make use of the web link in the article to view images from a range of different microscopes.
Developing Microscopy Skills: A World in a Hanging Drop
This practical is focused on developing microscopy skills, which can often be underdeveloped in first year A level students. The practical allows students to discuss the concepts of size in relation to magnification and resolution in relation to the different organisms they can see.
The hanging drop technique is a well-established method for examining living, unstained, very small organisms. The traditional procedure involves a glass slide with a central circular concavity into which a drop of fluid ‘hangs’ from a coverslip. Cavity slides are relatively expensive, and coverslips are very fragile. The apparatus described in this procedure is cheaper, more robust and less fiddly to work with.
Hemocytometer *suitable for home teaching*
Everything you need to know on cell counting with a hemocytometer, serial dilutions, culturing and counting yeast cells. This is a good source of worksheets, videos and protocols.