1. The Science of Biology
Chapter 1

2. Six Steps to Scientific Method
Defining the Problem:
Be specific
Research the topic

3. 2. Formulating a hypothesis
Hypothesis = a possible explanation for an observed set of facts.

4. 3. Testing the hypothesis
Experimentation
Must have a variable or single factor being tested
Experimental set: part of experiment that contains the variable.
Control set: exactly like the experimental except NO VARIABLE.
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5. Variables INDEPENDENT
Factor or value that is not affected by another variable.
DEPENDENT
Factor or value that is affected or determined by another factor or variable.

6. 4. Observing and Measuring
Be specific with observations.
Write down all data.
5. Analyzing & Drawing Conclusions
A chart or graph is often used to help clarify information.

7. 6. Reporting Observations
* If an experiment cannot be repeated the results cannot be considered valid.

8. THEORY : LAW : Theories & Laws
Explanations to phenomena supported by evidence.
LAW :
A theory which has been accepted as true.

9. How do we know when something is ALIVE?
Made of one or more cells
A small collection of living matter enclosed by a barrier.
Organisms can be either unicellular or multicelluar.

10. 2. Living things reproduce
ASEXUAL
Offspring comes from a single parent
Offspring is identical to parent.
SEXUAL
Offspring is usually a result of two parents.
Offspring is often similar to parents but not identical.

11. 3. Living things are based on a genetic code.
Inheritance of traits are carried by a molecule of nucleic acid.
Usually DNA (deoxyribonucleic acid)

12. 4. Growth and Development
All living things can increase in size (growth) and change over time (development)
All living things have a finite life span.

13. 5. Living things obtain and use materials and energy
Metabolism : All of the chemical reactions and processes that build up and break down materials in an organism

14. 6. Living things can respond to the environment
7. Living things try to maintain an internal balance
Known as homeostasis

15. 8. Living things evolve over time
As a species, living organisms can change over a given amount of time.

16. Tools of the Biologist
Section 4

17. The Light Microscope Simple Microscope Only one lens.
Compound Microscope
Uses two lenses, an optical system, a mechanical system, and a light system.

18. Parts of the microscope:
Optical system
Lenses
1.Objective lens
low, med and high power
2. Ocular lens
eyepiece

19. B. Mechanical system Base Arm Nosepiece Stage Clips Body tube
Coarse adjustment knob
Fine adjustment knob

20. C. Light System
Mirror
Internal light source
Diaphragm

21. Magnification vs Resolution
enlargement of the object’s image
Resolution:
sharpness of an image; the ability to distinguish between separate points

22. Preparation of Specimens
Must be thin enough for light to pass through.
Fixation
Cutting material into small pieces and allowing it to soak in a fixative
Embedded in liquid wax or plastic
Sectioned or sliced
Often stained

23. Phase-contrast microscope
Allows the observer to see details in living specimens without staining.

24. Stereomicroscope
Low magnification
3D images
Great for dissections

25. Electron Microscopes 250,000 X Smaller magnification
Transmission electron
250,000 X
Scanning electron
Smaller magnification
Can see many many fine details

26. SEM images
Human red blood cells and a housefly.

27. Lab techniques
Centrifugation = used to separate materials of different densities.
Tissue culture = used to maintain living cells outside an organism’s body.
Chromatography = separation of different substances on the basis of their chemical or physical properties.

28. Techniques continued…
Electrophoresis = an electric current is used to separate substances.
Spectrophotometry
Computers
MRI (magnetic resonance imaging)
CAT (computerized axial tomography)
ultrasound