Magnification

Magnification Photomicrographs often have magnification bars to allow calculation of the actual size of specimens. 4.55μm

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

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 = 126000.0 1.2 6 0 0 0 0 .

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 = 0.0000126 0.0 0 0 0 1.2 6

Have a go at these: 14500.0 1.45 x 104 = 0.37 x 107 = 86.41 x 10-3 = 3700000.0 0.08641 0.0265

Figure 5.1 Paramecium caudatum x600

Figure 5.1 Paramecium caudatum Measured length = 142mm 142 ÷ 600 = 0.237mm 0.237mm = 237μm x600

Figure 5.2 chloroplasts x9000

Figure 5.2 chloroplasts Mean measured length of the four largest chloroplasts = 39.25mm 39.25 ÷ 9000 = 0.0044mm 0.0044mm = 4.4μm x9000

Figure 5.3 a bacterium Measured length = 128mm 128 ÷ 0.002mm = magnification Magnification = x64000

Figure 5.4 seven week human embryo

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

Figure 5.5 head of a fruit fly

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

Figure 5.6 pollen grain

Figure 5.6 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 = 0.0376mm 0.0376mm = 37.6μm

Figure 5.7 red blood cells in an arteriole

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 = 0.0083mm 0.0083mm = 8.3μm

Figure 5.8 a mitochondrion

Figure 5.8 a mitochondrion Measured length of scale bar = 30mm Magnification = 30 ÷ 0.002 = x15000 Measured width = 34mm Actual width = 34 ÷ 15000 = 0.0023mm 0.0023mm = 2.3μm

Figure 5.9 bacteriophage [a type of virus]

Figure 5.9 bacteriophage [a type of virus] Measured length of phage = 29mm Magnification = 29 ÷ 0.0002 = 145000 Magnification = 1.45 x 105

Figure 5.10 potato cells starch grains

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

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

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