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