Bell ringer L3 Compare your calculations with your neighbor, discuss any differences.

Bellringer L4 Set up your microscopes and calibrate the x10 and x40 objective lenses Discuss with your partner: Which cell measurement would be more accurate and why? Measure at x10 and calculate cell size using x4 calibration and factoring in the magnification difference Measure at x10 and use the calibration for the x10 objective to calculate the cell size

Bell ringer 5 Look at the drawings and compare the quality of work. Identify good practice and necessary improvements

HW: Exam style question (10 marks) In this questions, one mark is available for the quality of written communication. Plant/animal cells* are also eukaryotic. Outline the functions(s) of each part of a plant/animal* cell.

Light microscopy

Specimens for Light Microscopes Sectioning: Some material distorts when you try & cut it into thin sections Specimens are embedded in wax Thin sections are cut without changing the structure of it. Staining: A lot of biological material is not coloured Chemicals that bind to the specimen allowing it to be seen Some stains are specific to cell structures e.g. Acetic orcein stains DNA dark red.

Object name: Onion cells Stain: Methylene Blue Magnification: x400 Name, Date: Cell wall Cell membrane Nucleus Cytoplasm Tonoplast Vacuole

Biological Drawings White paper + sharp pencil Safely carry out the practical as described. Take care to follow safety precautions indicated (especially using stains!) Biological Drawings White paper + sharp pencil Title, date and the magnification power Low power drawings - only the outline of the structures or tissues High power drawings - Individual cells are required. Draw large (~ 1/2 page), neat and tidy Draw what you see – don’t copy textbooks Draw with bold, dark, smooth lines.  Shading and the use of crayons are not encouraged. Draw freehand but use a ruler for underlining and labels. Never cross lines Include a scale bar that shows the actual size. Draw overview x4 Draw 3-4 connected cells with detail x10

Plant cells

Animal cells