Transcript
Page 1: Magnify-cent Biology!!

Magnify-cent Biology!!

IB Biology Topic 2

Page 2: Magnify-cent Biology!!

Learning OutcomesEveryone 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

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Now try the Magnification Revision poster as a group!

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Answers for the animal cellCalculate the magnification factorThe line 5 m is 20 mm long. So 20 000 m = 5 mMagnification is 20 000/5 = x 4 000. Calculate the length of structure GLength of G is 12 mm = 12 000 m Magnification is x 4 000Real size is 12 000/4000 = 3 m Calculate the diameter of structure BDiameter is 8 mm = 8 000 m Magnification is x 4 000Real size is 8 000/ 4 000 = 2m Calculate the diameter of the nucleusDiameter is 36 mm = 36 000 mMagnification is x 4 000so real size is 36 000/4 000 = 9 m Calculate the diameter of the cell at its widest point109 mm = 109 000 m = 109 000/4 000 = 27–25 mFor all the answers above there is a tolerance limit of + or – 0.5mm, so + or – 0.1 – 0.2 mThere 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.

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Answers for the plant cell

Calculate the magnification factor.The line representing 40 m is 25 mm or 25 000 m longTherefore, magnification factor is 25 000/40 = x 625. Calculate the thickness of the cellulose cell wall.Wall is 3.0 mm = 3 000 m Magnification is x 625Actual thickness of wall is 3 000/625 = 4.8 m Calculate the length of the cell.120 mm = 120 000 m magnification factor is x 625Actual length is 120 000/625 = 192 m Calculate the length of structure C.29 mm = 29 000 m magnification is x 625Actual length is 29 000/625 = 46.4 m Calculate the length of the vacuole.80 mm = 80 000 m magnification is x 625Actual length is 80 000/625 = 128 m.

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Learning OutcomesEveryone 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


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