Magnify-cent Biology!! IB Biology Topic 2
Learning Outcomes Everyone should: Compare relative sizes of biological molecules, viruses, cells and bacteria using appropritate SI units Most will: Calculate magnification from a scale bar Some might Calculate magnification and actual size of biological drawings and specimens
Now try the Magnification Revision poster as a group!
Answers for the animal cell Calculate the magnification factor The line 5 m is 20 mm long. So m = 5 m Magnification is /5 = x Calculate the length of structure G Length of G is 12 mm = m Magnification is x Real size is /4000 = 3 m Calculate the diameter of structure B Diameter is 8 mm = m Magnification is x Real size is 8 000/ = 2 m Calculate the diameter of the nucleus Diameter is 36 mm = m Magnification is x so real size is /4 000 = 9 m Calculate the diameter of the cell at its widest point 109 mm = m = /4 000 = 27–25 m For all the answers above there is a tolerance limit of + or – 0.5mm, so + or – 0.1 – 0.2 m There are other perfectly correct ways of doing the calculation, so if your method is different, but arrives at the correct answer, then that is fine.
Answers for the plant cell Calculate the magnification factor. The line representing 40 m is 25 mm or m long Therefore, magnification factor is /40 = x 625. Calculate the thickness of the cellulose cell wall. Wall is 3.0 mm = m Magnification is x 625 Actual thickness of wall is 3 000/625 = 4.8 m Calculate the length of the cell. 120 mm = m magnification factor is x 625 Actual length is /625 = 192 m Calculate the length of structure C. 29 mm = m magnification is x 625 Actual length is /625 = 46.4 m Calculate the length of the vacuole. 80 mm = m magnification is x 625 Actual length is /625 = 128 m.
Learning Outcomes Everyone should: Compare relative sizes of biological molecules, viruses, cells and bacteria using appropriate SI units Most will: Calculate magnification from a scale bar Some might Calculate magnification and actual size of biological drawings and specimens