Intro to Science Sept 2011 Biology 112. The Goals of Science 1. Deals only with the Natural World The supernatural is outside the realm of science

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


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!!!


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.


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!


Repeating Investigations – TRIALS!!!

Spallanzani's Test of Redi's Findings

Gravy is boiled. Gravy is boiled.

Which variables are controlled??


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!


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.


Pasteur’s Experiment

Broth is boiledBroth is freeof microorganismsfor a year.

Curved neck isremoved.

Broth is teeming with microorganisms.


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


1-3 Studying Life


So…If Biology is the study of living things….What makes something living?


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)

Documents

Intro to Science Sept 2011 Biology 112. The Goals of Science 1. Deals only with the Natural World The supernatural is outside the realm of science