Tools of the Biologist- Name That Tool!1

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A Review of Using SI Units in Biology

Biology labs often include the collection of data. Data not only includes making observations but recording measurements such as length, mass, volume and temperature. SI measurements are based upon a basic unit.

meter gram liter O Celsius

All SI units are based upon the multiples of 10.

Micro Milli Centi Basic Unit Kilo

/ 1000 /10 /100 /1000

When going from a smaller unit to a larger unit DIVIDE

or Move the decimal point to the left

Micro Milli Centi Basic Unit Kilo

X 1000 X 10 X 100 X 1000

When going from a larger unit to a smaller unit MULTIPLY

or Move the decimal point to the right

The Compound Light MicroscopeMagnifies specimen. Allows light to pass through the specimen. A reverse image.

1. Body Tube2. Nosepiece3. 4X Objective4. 10X Objective5. 40X Objective6. Stage Clips7. Diaphragm8. Lamp9. Ocular 10.Arm11.Stage12.Coarse Adjustment13.Fine Adjustment14.Base

Ocular or Eyepiece: Part of the microscope you look through.Magnifies image 10X.

Nosepiece: Rotates to change objective.

Objective: 4X low power- magnifies 4X. 10X medium power –magnifies 10X. 40X high power- magnifies 40X.

Stage: Where specimen is placed for viewing.

Stage Clips: Holds slides in place.

Diaphragm: Controls the amount of lights entering the microscope.

IrisDiaphragm

DiscDiaphragm

Coarse Adjustment Knob: Used for focusing under low power.

Fine Adjustment Knob: Used for focusing under high power.

Total Magnification: Ocular X Objective Ocular = 10X Low power Objective = 4X 10 X4 = 40X Total Magnification

Field of View: Circular area of light you observe when looking into microscope.

As magnification increases from low Power 4X to high power 40X, the size of the field the field of view decreases, And you will see more detail.

Reverse Image: When observing specimens in the microscope the Imaged you observe is a reversed image of how it sits on the slide.e

e

Resolution: The resolving power of a microscope is the ability to Clearly determine two separate points, or objects, as singular,Distinguishing entities.

Depth of Field: Refers to the thickness of the plane of focus. With a large depth of field (low power), all of the threads can be in focused at the same time. With a smaller or narrower depth of field (high power), only one thread or a part of one thread can be focused, everything else will be out of focus. In order to view the other threads, you must focus using the fine adjustment, downward to view the ones underneath and upward to view the ones that are above. 

Calculating High Power Field Diameter

Low Power Magnification = X (High Power Field Diameter) High Power Magnification Low Power Field Diameter

Measuring Field Diameter

______________mm ________________um

4 x ------- = ------- 40 4

Cross multiply40X = 16Divide each Side by 40

40X 16------- = -------40 40

X = 0.40 mm

0.40 mm = ____________ um

Calculate the width of one cell observed under high powerWith a field diameter of 0.30mm

0.30 / 2 = __________mm

0.30/ _________ = _________mm