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.
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Links and Resources
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.
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.
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.
This issue of the Big Picture, from the Wellcome Trust, provides a very useful resource that could be used in a variety of ways for teaching the topic of cell structure and function at A level.
The resource includes a full page illustration of an animal cell, which is also available as a poster.
There are then a range of short articles on topics such as: what are cells for? What happens when cells die? This resource would be suitable for flipped learning. Learners could be asked to review particular articles before a lesson; this will allow them to become familiar with key vocabulary and concepts even if they do not fully understand it all. Concepts would then be covered within the lesson to consolidate learning.
Alternatively individual students or pairs of students could be given one short article to read and then give a presentation/talk to the rest of the class on the content of the article they reviewed.
Also included in this resource is material on stem cells, short articles and a lesson plan to help students discuss the moral and ethical issues around the use of stem cells.
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.
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.
This pack is an extensive resource with an environmental focus. Within this particular pack is a section on cell structure and function. This is found in section 2A 3.5. The relevant text starts on page 72, until page 77, which students could read through independently.
The questions on pages 78 to 79 are useful, but not particularly different to any that will be found in most text books. Question six however, where students are asked to produce a magazine article on the evolution of cells, based on some provided information, is a substantial activity which would provide challenge for A level students.
Although this is quite a basic interactive resource, there would still be value in A level biologists using this. It would work well as a plenary activity to recap some important knowledge and understanding on cell structure, function and the use of different microscopes.