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Unit C:
Cycling of Matter in Living Systems
Aristotle(384 BC – 322 BC)
• He was one of the first Greek philosophers who used the Scientific Method of observing, recording, reasoning, and interpreting in attempt to explain the world around him.
• Aristotle is known as “The Father of Biology.”
A compound microscope uses more than one lens to magnify objects.
Hooke’s three-lens system has two lenses in the ocular.
Robert Hooke(1635 – 1703)
Robert Hooke coined the term “cells” when he observed cork under his microscope. He named the tiny chambers as such because they reminded him of the rooms that monks occupy in a monastery.
Hooke’s drawing of cork cells
Antoni van Leeuwehoek(1632 –
1723)
Leeuwenhoek was the first person to observe the movement of living cells.
“animalcules”
1.Eye Piece or Ocular Lens.
2.Coarse Focus Adjustment
3.Arm
4.Stage Clip
5.Fine Focus Adjustment
6.Base
7.Lamp
8.Diaphragm
9.Stage
10.Objective Lenses
11.Revolving Nosepiece
12.Body Tube
text pg. 478
The magnification tells us how much larger (or smaller) the picture is than the real size of the specimen under the microscope.
magnification = (objective lens) (ocular lens)
Skill Practice pg. 244What is the magnification if the following combinations of lenses are used?
a) a 2.5X low-power objective lens and a 10X eyepiece
b) a 100X low-power objective lens and a 10X eyepiece
25X
1000X
Unit Equivalent Measurement
centimetre (cm) 1/100 metre; 10–2 m
millimetre (mm) 1/10 centimetre; 10–3 m
micrometre - also called the micron (μm)
1/1000 millimetre; 10–6 m
nanometre (nm) 1/1000 micrometre; 10–9 m
angstrom (Å) 1/10 nanometre; 10–10 m
(see data booklet)
Micro-organisms like bacteria and viruses can range in size from 10 µm to just a few nanometres.
To convert from one unit to another, we use a conversion factor. It is a fraction where the numerator is equivalent to the denominator.
Examples
1000 m
1 km -6
1 μm
10 m
1) 20 nm = ? m 20 nm-910 m
1 nm
= 2.0 × 10-8 m
2) 400 pm = ? mm
400 pm-1210 m
1 pm
-3
1 mm
10 m
= 4.00 × 10-7 mm
The field of view is the entire area that you see when you look through the microscope.
To compare different fields of view, we usually measure their diameters.
100 X
1000 X
Magnification increases the size of what you see BUT decreases the amount of the object in view.
Since the field of view decreases in size in direct proportion to the increase of the magnification, we can calculate the size of the other fields of view.
For example: If the field of view is 4000μ at 40X, it will be 10 times smaller at 400X, or 400μ in size.
high power field diameter low power magnification
low power field diameter high power magnification
MagnificationField of View
(mm)Field of View
(µm)
40X 4.0
100X 1.6 1600
400X
4000
0.4 400
text p. 481
400 µm
field diameterActual Size of Object
number of objects estimated to fit across the field of view
400μmsize of object =
3.5
size of object = 114 μm
Actual Size Diagram Size Scale
1.1 mm 110 mm 100:1 (or ×100)
2.6 mm 5.0 cm (50 mm) 19:1 (or ×19)
To calculate actual size and scale of a diagram of a specimen under a microscope, you measure (or calculate) the diameter of the field of view (on the microscope) and the actual size of the finished diagram (on your page).
diagram size of objectsscale
acutal size
must be in the same units!
read pages 242 – 246
C1.1 Check and Reflect
page 246 #’s 1 – 8
Line Masters 1 and 2