intro to science sept 2011 biology 112. the goals of science 1. deals only with the natural world...
TRANSCRIPT
Intro to ScienceSept 2011
Biology 112
The Goals of Science
1. Deals only with the Natural World
The supernatural is outside the realm of science
The Goals of Science2. Collect & Organize Data
Goals of Science3. Propose Explanations that can be tested
In Summary….. SCIENCE is a BODY of KNOWLEDGE
that EXPLAINS the NATURAL World.
Science Begins with Observation – How are your Skills?
OBSERVATION1. Quantitative – a quantity/number or
measure2. Qualitative – a quality/characteristic;
description
Inference A logical interpretation based on prior
knowledge Examples of Inferences? What can be the problem with
inferences?
http://www.youtube.com/watch?v=tiy1MeXzhfA
Hypothesis A proposed explanation; must be
TESTABLE; written in an “If….then” format1.If I give my dog Purina dog food for a
month, then he will not shed as much.2.If I use miracle grow then my plants
will produce more tomatoes.3.If I use the drug Avapro for a week
then my blood pressure will be lower
Scientific Inquiry~inquisitive thinker’s!!! Scientists make observations, ask
questions and then try to answer them through research and experimentation.
http://www.youtube.com/watch?v=VjE0Kdfos4Y
Narrowing in on Science BIOLOGY – One Branch of Science Study of LIVING things
Copyright Pearson Prentice Hall
A Few Branches of Biology:ZoologistsBotanistsPaleontologistsCell BiologistsGeneticistsMicrobiologistsEcologists
Biology is very broad (Remember it is the study of LIVING things…and there are LOTS of living things!!!!!)
Terminology rich; very descriptive and has it’s own language~– Handout #1 – Give it a try
Copyright Pearson Prentice Hall
1-2 How Scientists Work
Scientists make educated guesses about how things work the way they do. These are called HYPOTHESIS.
How do scientists test hypotheses?A hypothesis should be tested by an experiment in which only one variable is changed at a time.
Scientific Method Summary1) Ask questions, make observations2) Gather information 3) Form a hypothesis (educated guess)4) Set up a controlled experiment Manipulated variable - the
variable that is deliberately changed (aka independent variable)Responding variable is variable that is observed (aka dependent variable)
5)Record and analyze results 6)Draw a conclusion7)Repeat & share findings
Scientific Method – Step 1:
Ask Questions/Make Observations: 2300 years ago people thought that some
“special force” brought some things into being from nonliving material
Ex: Beetles just “appeared” on cow dung Mice were “found” on grain Maggots “showed up” on meatGood thing we don’t’ just rely on observations!!!
Copyright Pearson Prentice Hall
The idea that living things arise from non-living matter is called:spontaneous generation OR abiogenesis.
In Aristotle’s time, people hypothesized that maggots spontaneously appeared on meat.
FRANCESCO REDI – BEGAN CHALLENGING ARISTOTLE BY ASKING QUESTIONS and Following the steps of the scientific method!!
In 1668, Redi proposed a different hypothesis: that maggots came from eggs that flies laid on meat.
Copyright Pearson Prentice Hall
Redi’s Experiment
Controlled Variables:jars, type of meat,Location, temperature,time
Covered jarsUncovered jars
What do you think are the manipulated and responding variables in this experiment??
John Needham – mid 1700’s – SG is BACK!??? English Scientist who tried to attack
Redi’s work. He heated a flask of gravy for a short
time and corked the flask and microorganisms appeared.
He believed that the little “animalcules” must have come from the gravy!
Copyright Pearson Prentice Hall
Repeating Investigations – TRIALS!!!
Spallanzani's Test of Redi's Findings
Gravy is boiled. Gravy is boiled.
Which variables are controlled??
Copyright Pearson Prentice Hall
Spallanzani – Disproving SG!
Flask is open. Flask is sealed.
•Is the flask the manipulated or responding variable??
Copyright Pearson Prentice HallH
Gravy is teemingwith microorganisms.
Gravy is free ofmicroorganisms.
Helped prove the theory of BIOGENESIS!!!! Living things come from other living things!
Copyright Pearson Prentice Hall
Pasteur's Test of Spontaneous Generation
Louis Pasteur conclusively disproved the hypothesis of spontaneous generation.
Pasteur showed that all living things come from other living things.
Copyright Pearson Prentice Hall
Pasteur’s Experiment
Broth is boiledBroth is freeof microorganismsfor a year.
Curved neck isremoved.
Broth is teeming with microorganisms.
Copyright Pearson Prentice Hall
The Impact of Pasteur’s Work
He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms.Pasteurization of dairy products
SCIENTIST SUMMARY:PRO SG: Aristotle, NeedhamANTI SG: Redi, Spallanzani, Pasteur
Copyright Pearson Prentice Hall
1-3 Studying Life
Copyright Pearson Prentice Hall
So…If Biology is the study of living things….What makes something living?
Copyright Pearson Prentice Hall
Living things share the following characteristics:*REFERENCE PAGE – pages 16/17 of student text!!
1. Made of cells
2. Reproduction
2. Reproduction
3. Universal genetic code
4. Grow & Develop
5. obtain and use materials and energy
6. respond to stimuli
7. Maintain a stable internal environment (called homeostasis/equilibrium)
8. change over time
Martian & The Car Activity~
MicroscopesAnton van Leeuwenhoek (1632-
1723) was responsible for the first “microscope” as we know them today
Due to his knowledge of lenses he was able to construct a piece of equipment that made things appear closer and larger.
Microscopy and Microscopy and MeasurementMeasurementMicroscopes – produce an
enlarged image of an object Used to study organisms, cells, and cell
parts Increase in apparent size is called
magnificationmagnification The ability to show details clearly is called
resolutionresolution Microscopes vary in both magnification
and resolution
40
Compound Light Microscope (2 lens-microscope)
Uses light passing through a medium of liquid to view a specimen
Uses generally a 10X ocular lens in addition to a 4x, 10x, 40x objective lens
Magnification = ocular x objective
Limited in it’s magnification Used to view living and dead specimens
Magnification Example: Using the compound microscope in your
classroom, you are asked to view a piece of hair under the medium power objective. What is the total Magnification of the hair being viewed?
What exactly does that mean?
Types of MICROSCOPES Light vs. Electron Smallest size seen with the Naked Eye is…. 0.2mm = one ridge on your finger print
(resolution OR resolving power) Light Microscopes can view 0.0002 mm Electron Microscopes can view 0.000000002
mm (0.2 nm)
Parts of the Compound Microscope – Fill in your sheet as we go!! http://www.biologycorner.com/
microquiz/#
Microscope Use
http://www.youtube.com/watch?v=scEhgAiazzU
Focusing a Microscope Always start with the low power
objective (4X). Odds are, you will be able to see something on this setting. Use the Coarse Knob to focus.
Once you've focused on low power, switch to Med Power (10X). Use the Coarse Knob to refocus. Again, if you haven't focused on this level, you will not be able to move to the next level.
Now switch to High Power. (40X) If the specimen is too light or too dark,
try adjusting the diaphragm.
Making a Wet Mount1. Gather a thin slice/piece of whatever your
specimen is. your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw, and you will not be able to view it under High Power.
2. Place ONE drop of water/dye directly over the specimen. If you put too much water, then the coverslip will float on top of the water, making it hard to draw the specimen, because they might actually float away. (Plus too much water is messy)
3. Place the coverslip at a 45 degree angle (approximately) with one edge touching the water drop and then gently let go. Performed correctly the coverslip will perfectly fall over the specimen
Finished with your Microscope?
1. Store microscopes with the scanning objective (4X) in place.2. Wrap cords and cover microscopes.3. Wash slides/slips in the sinks and dry them, placing them back in the slide boxes to be used later. 4. Carry with 2 hands (arm/base)5. Put back in the correct location
Transmission Electron Microscope
•Uses electrons instead of light
•Capable of over 200,000X magnification
•Specimens that contain many layers of cells, such as blood vessels, cannot be examined
•A thick specimen would absorb all the electrons and produce a blackened image
•Only view thin sections encased in plastic
TEM cont..
Scanning Electron Microscope (SEM) Produces a 3-D image View up to 100,000X Takes “pictures” of surfaces Specimens are usually preserved,
coated in a metal, dehydrated…so specimen being viewed is non-living.
Scanning Electron Microscope
SEM cont…
Guess?
Guess??
Guess??
Guess??
Rules for Biological Diagrams See handout (rules/practice
assessment)
Figure 1 – Moss Cross-section
Biological Diagrams - Lab #1 Following all steps for biological
diagrams complete the following: (Do two drawings on one page of
plain paper)1. Obtain a sample from the front
and draw the specimen in the container (do not draw the bottle)