Part 3- Tools and Techniques

* Because researchers need to replicate each other’s experiments and most experiments involve measurements, scientists need a common system of measurement. * Most scientists use the metric system when collecting data and performing experiments.

* The metric system is based on multiples of 10, which makes it easy to use! * The official name of the metric system is Systeme International d’Unites. The English translation of this French title is the International System of Units, abbreviated SI.

Base QuantityNameAbbreviation Length Mass Volume Time

PrefixAbbreviationFactor of Base Unit kilo- hecto- deka- BASE UNIT deci- centi- milli-

* When scientists collect data, the are often trying to find out whether certain factors changed or remained the same. They also try to look for patterns in the data. Often, the simplest way to do this is to record the data in a table and then make a graph. Temperatures in NYC DayTemperature 143 degrees F 253 degrees F 350 degrees F 457 degrees F 559 degrees F 667 degrees F

* Although you may be able to detect a pattern of change from a data table, a graph of the data can make a pattern much easier to recognize and understand.

* Definition of a compound light microscope: microscope that shines light through a specimen and has 2 lenses to magnify an image * 4 Major Parts of a Compound Light microscope and their functions:

* Definition of magnification: how much larger an object appears compared to its real size

* How is the magnification of a microscope computed? Eyepiece mag. x objective mag. Total mag. of a microscope is eyepiece mag. x mag. of highest power objective lens

* Definition of resolution: power to show details clearly in an image * What happens to the resolution of light microscopes at powers of magnification beyond about 2,000x? Image becomes fuzzy

* What is an electron microscope? Uses a beam of electrons to produce an enlarged image of a specimen 2 main types- Scanning (SEM) Transmission (TEM)

* Advantages of electron microscopes over light microscopes: 1. More powerful magnification 2. More powerful resolution 3. Some can show contours of individual atoms in a specimen!

* Disadvantages of electron microscopes: 1. Images in black and white (although computers can add artificial color) 2. Cannot be used to view living specimens

* What are some safety hazards that may pop up in the biology lab or during field studies? Chemical, physical, radiological, burns, cuts, bacteria, bites, falling, electricity, broken glass (just to name a few!)

* The single most important rule for lab safety is simple: Always follow the teacher’s directions exactly- if in doubt, ask!

* Other lab safety tips: - Use safety goggles, gloves, etc. - Wash hands - Clean up spills - Do NOT FOOL AROUND!!

* Remember- you are responsible for your own safety and that of your classmates and teacher!!