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Magnification
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Magnification Photomicrographs often have magnification bars to allow
calculation of the actual size of specimens. 4.55μm
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Magnification In this exercise you will calculate the magnification and/or true size of the following: 1 2 3 4 5 8 6 7 10 9
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Before we begin: Note: Numbers written like this: 1.26 x 105 mean you move the decimal point to the right. In this case you move it 5 times: 1.26 x 105 = .
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Before we begin: Note: Numbers written like this: 1.26 x 10-5 mean you move the decimal point to the left. In this case you move it 5 times: 1.26 x 10-5 =
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Have a go at these: 14500.0 1.45 x 104 = 0.37 x 107 = 86.41 x 10-3 =
0.0265
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Figure 5.1 Paramecium caudatum
x600
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Figure 5.1 Paramecium caudatum
Measured length = 142mm 142 ÷ 600 = 0.237mm 0.237mm = 237μm x600
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Figure chloroplasts x9000
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Figure chloroplasts Mean measured length of the four largest chloroplasts = 39.25mm 39.25 ÷ 9000 = mm 0.0044mm = 4.4μm x9000
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Figure 5.3 a bacterium Measured length = 128mm
128 ÷ 0.002mm = magnification Magnification = x64000
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Figure 5.4 seven week human embryo
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Figure 5.4 seven week human embryo
Measure the actual length of the scale bar and divide by the length it represents Magnification = 25 ÷ 10 = x2.5
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Figure 5.5 head of a fruit fly
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Figure 5.5 head of a fruit fly
Measure the actual length of the scale bar and divide by the length it represents Magnification = 12.5 ÷ 0.2 = x62.5
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Figure pollen grain
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Figure pollen grain (a) Measure the actual length of the scale bar and divide by the length it represents Magnification = 25 ÷ 0.02 = x1250 (b) 47mm (c) 47 ÷ 1250 = mm 0.0376mm = 37.6μm
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Figure 5.7 red blood cells in an arteriole
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Figure 5.7 red blood cells in an arteriole
Measured length of scale bar = 30mm Magnification = 30 ÷ 0.01 = x3000 Diameter = 25mm [approx] Actual diameter = 25 ÷ 3000 = mm 0.0083mm = 8.3μm
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Figure 5.8 a mitochondrion
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Figure 5.8 a mitochondrion
Measured length of scale bar = 30mm Magnification = 30 ÷ = x15000 Measured width = 34mm Actual width = 34 ÷ = mm 0.0023mm = 2.3μm
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Figure 5.9 bacteriophage [a type of virus]
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Figure 5.9 bacteriophage [a type of virus]
Measured length of phage = 29mm Magnification = 29 ÷ = Magnification = 1.45 x 105
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Figure potato cells starch grains
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Figure 5.10 potato cells Mean diameter of the cells = 38mm [approx]
Measured length of scale bar = 24mm Magnification = 24 ÷ 0.1 = x240 Diameter of the cells = 38 ÷ 240 = 0.158mm 0.158mm = 158μm
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Magnification The resolving power of the unaided eye is approximately 0.1mm The maximum useful magnification of light microscope is around x1500 Plant and animal cells typically measure around 20µm Many organelles are as small as 25nm – beyond the resolving power of the light microscope [wavelength of light is 500nm approx] Wavelength of electron beam is 0.005nm Maximum resolving power of the electron microscope is 0.2nm
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Question 11 bacteriophage 0.2μm bacterium 2.0μm mitochondrion 2.3μm
Structure Size Kind of structure Visible at x1500? bacteriophage 0.2μm virus bacterium 2.0μm prokaryotic cell (just) mitochondrion 2.3μm eukaryotic organelle chloroplast 4.4μm red blood cell 8.3μm eukaryotic cell pollen grain 38μm potato cell 158μm paramecium 237μm eukaryotic organism embryo 30mm
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