Introduction to the
Biology Lab
The Scientific Method
LABORATORY SAFETY
Student Conduct
• Do NOT smoke, eat, drink, or bring food or drinks
into the laboratory room
• Do NOT apply cosmetics or handle contact lenses
• Wash your hands thoroughly with soap and water
before leaving the laboratory room each day
• Do NOT remove organisms or chemicals from the
laboratory
• Work carefully and methodically
• COME PREPARED TO LAB FOR THAT DAY’S WORK
Basic Laboratory Safety
• NO OPEN-TOED SHOES
• Secure loose hair and clothing to avoid accidents
• Place non-essential books, etc. out of the way of
your experiments
• Never pipette by mouth
Safety Equipment
• Know the location of the First Aid Kit
• Know the location and proper way to use the
Shower
• Know the location and proper way to use the
Eye Wash Basin
• NOTIFY YOUR INSTRUCTOR OF ANY EVENT
THAT NECESSITATES THE USE OF THESE
Disposing of Materials
• Common paper and uncontaminated towels can be
placed into the normal trash
• Cotton swabs, coverslips, and other used lab material
MUST be placed into the red, plastic trash receptacle
• Broken glassware MUST be placed in the cardboard
“sharps” container for glassware
Care of Microscopes
• Microscopes are located at each lab station
• Following their use, miscroscope:
1. Scanning (4X) lens should be in place
2. Stage should be at lowest setting
3. Rheostat should be adjusted to its lowest setting
4. Cord should be wrapped carefully around the base and
not “flopping” around
5. Ocular lenses should face back of cabinet
YOUR INSTRUCTOR WILL INSPECT THEM BEFORE YOU ARE
PERMITTED TO LEAVE
Care of the Lab
• Place seats back under benches before you
leave
• Wipe down the sink-tops with paper towel if
you are among the last students in the lab
– Remove any paper towels left behind by less
conscientious students
THE LAB SHOULD LOOK AS NICE AFTER YOU
ARE DONE AS IT DID BEFORE YOU STARTED
Check Your Understanding
• What is the last thing you should do each day before leaving the lab?
• What is the only mandatory piece of “clothing” required for you to be able
to work within the lab?
• Differentiate between where you should dispose of paper towels and
other paper items, cotton swabs and other used lab items, and broken
glassware. How should you clean up a piece of broken glassware?
• Discuss the proper way your microscope should be put away after each
use.
• Following completion of any lab session, describe how your:
– lab bench should look (including chair).
– lab sink should look.
Scientists Make Observations and Then Form and Test Hypotheses
SCIENTIFIC METHOD
Scientific Inquiry
• Science is a “way of knowing”
– Understanding of the natural world
• Inquiry is the methodical approach for
deriving answers to questions posed by
observations of the world around us
Making Observations
• Recorded observations are data
1. Qualitative – descriptions rather than measurements
2. Quantitative – recorded measurements (tables/graphs)
• Leads to Inductive Reasoning
–
–
Generalizations are derived from numerous specific
observations
e.g. “Goldfish and roses and mushrooms are made of
cells, therefore all organisms are made of cells”
Forming and Testing Hypotheses
• Seeks to explain the cause of behind an observation
– Hypotheses provide tentative answers based on available
data and inductive reasoning
• Deductive Reasoning is used to validate hypotheses
– Uses general premises to extrapolate what the results
should be if the premises are true
– “if…then” logic (e.g. “if humans are organisms, then
humans are made of cells”)
Types of Hypotheses
• Null is stated as a negative
– e.g. “Humans are not made of cells”
• Alternative is stated as a positive
– e.g. “Humans are made of cells”
• The null and alternative hypotheses are
mutually exclusive and both cannot be true
Hallmarks of a GOOD Hypothesis
• It must be testable
– Hypotheses must have a way of being validated
• It must be falsifiable
– Hypotheses can NEVER be proven true beyond a shadow
of a doubt
– New experimental techniques may invalidate (falsify) it
Experimental Controls and
Repeatability
• Controlled Experiments compare an
experimental group with a control group
– Should differ in only one factor (Independent
Variable)
– The control group is used to cancel out all effects
that the scientists is NOT interested in examining
• Observations in science are only convincing if
the results are repeatable
Theories in Science
1. Scientific theories are much broader in scope
than simple hypotheses
2. Scientific theories typically give rise to many
new hypotheses that can be tested
3. Scientific theories are supported by a wider
range of experimental evidence than single
hypotheses
4. Theories, like hypotheses, are falsifiable
given new experimental data
Check Your Understanding
• Discuss the implication of the fact that lab work performed by scientists
uses scientific inquiry.
• Differentiate between quantitative and qualitative data (observations).
• Differentiate between deductive and inductive reasoning. How does each
contribute to our understanding of the natural world around us?
• Define hypothesis. Differentiate between a null and an alternative
hypothesis. What are the hallmarks of a “good” hypothesis?
• Explain what a controlled experiment is. Why is important to always strive
to perform a controlled experiment? Differentiate between a dependent
and an independent variable.
• Compare and contrast a theory and a hypothesis.