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This material acts as a study guide for unit A4 Cells, the bricks of the body and A5 Tissues organs and systems in Biology by Roberts, and unit unit A3 Cells, the bricks of the body and A4 Tissues organs and systems in Biology by Roberts, also by Roberts. It leads on to other parts of the cell activity section of the syllabus.

Suggested teaching strategy

In addition to the 7 characteristic processes of life, most living organisms are composed of similar component parts: cells.
There have some features of cells which are shared by animals and plants, whilst others are only found in cells of plants.
It is likely that students will recall some details of cell structure from Key Stage 3.

Possible problems

Confusion between words like cytoplasm and chloroplasts
Distinction between a cell membrane and a cell wall

Practical activities

Using a microscope to examine cells: cheek cells and onion epidermis cells are the most likely candidates. Pieces of Elodea leaves will clearly show chloroplasts, and cells of hairs from the middle of Tradescantia flowers will reliably show cytoplasmic streaming when microscopes are properly set up (as a demo?). However, Tradescantia may not be in flower!

It is probably worthwhile referring to the Activities section of Studying Biology for background rules on using the microscope.

It is probably also a good idea to do the onion before the cheek cells; there will be fewer problems with focussing, and it may be possible to prepare sections of onion epidermis beforehand.

If the mustard seeds from the previous practical have suitably germinated, it may be possible to use the seedlings to demonstrate root hairs. I have frequently found that these hairs are mistaken for mould growth!

Although the section on obtaining cheek cells is politically correct, I have always found it best to use wooden tongue depressors (as used by GPs); if methylene blue is used as a stain (already on the slides) then there is (almost) no chance that these will be used twice, as the wood will absorb the stain!

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