1. Scientific Method and Experimental Design

2. Science is always advancing and changing
The World of Science
Science is always advancing and changing

3. What is the scientific method?
The scientific method is a set of steps that scientists take to investigate and acquire new knowledge
There are 6 steps in the scientific method!

4. 6 Steps to the Scientific MethodG H E O C
State the PROBLEM (question)
GATHER INFORMATION
Form a HYPOTHESIS
Design an EXPERIMENT
ORGANIZE & ANALYZE DATA
Form a CONCLUSION

5. Designing an Experiment
Multiple factors go into an experiment
Independent Variable
Manipulated variable; the thing you change in the experiment
Dependent Variable
Responding variable; the thing that changes as a result of you changing the independent variable
Control Group
Experimental group you do not change; used to compare results!
Constants
Controlled variables; things you keep the same/consistent to avoid skewed results or error

6. Improving an Experiment
Increase number of test subjects; helps to eliminate bias
Repeat the experiment to collect more data
Ensure only one independent variable is being tested!

7. Let’s look at an example…
Guppies have an innate preference for the color orange
South American/Caribbean origin
Purpose/Question: Does a guppy’s preference for the color orange affect its feeding habits?
Experiment: 100 guppies
10 tanks, 10 guppies per tank
1 tank with white paper, 9 tanks with half the tank covered in yellow paper, half in orange
Automatic feeders, both sides of the tank
IV: Paper color on tank
DV: Number of guppies on each side of the tank
Controls: fed on both sides of the tank, same time of day feeding

8. Science of Biology
Chapter 1

9. What is biology?
Biology is the study of life!

10. Spontaneous Generation
Idea that life can arise from nonliving matter
Francesco Redi
Italian physician
Experiment with meat & maggots
Independent variable?
Exposure to air/Gauze Covering
Dependent variable?
Appearance of maggots

11. Then there were two more guys…
Needham: heated a bottle of broth to kill any microorganisms, left the bottle for a few days, looked at the broth under the microscope and found that the broth contained microorganisms again
Spallanzani: boiled broth in two bottles, left one bottle open and one closed, and found that new microorganisms appeared only in the open bottle.
Needham’s Experiment
Spallanzani’s Experiment

12. Finally Disproving Spontaneous Generation
Pasteur
Heard of everyone’s work on spontaneous generation
Designed a flask to test the theory
Boiled them, used the neck of the flask to “catch” microorganisms that may infest the broth
Nothing in unbroken flask after days of waiting

13. What characteristics make something living?
Question of the Day:
What characteristics make something living?

14. 8 Characteristics of Life
Living things are made up of cells
Cell: smallest unit of life
Living things reproduce
Sexual reproduction: cells from two different parents unite to form the first cell of a new organism
Asexual reproduction: single parent produces offspring
Living things are made up of DNA
Living things grow and develop
Cell specialization

15. 8 Characteristics of Life (ctd.)
Living things obtain and use materials and energy
Metabolism: combination of chemical reactions through which an organism builds up or breaks down materials
Living things respond to their environment
Stimuli: signal to which an organism responds
Living things maintain a stable internal environment
Homeostasis: process by which organisms maintain a stable internal environment
Living things change overtime
Evolution

16. Microscopes
Light Microscopes: produce magnified images by focusing visible light rays
Compound light microscope: allows light to pass through the specimen and uses two lenses to form an image

17. Parts of a Microscope

18. Microscopes (ctd.)
Electron Microscopes – produce magnified images by focusing electrons; lenses are made of electromagnets
Transmission electron microscope (TEM) – show detail inside of specimen
Scanning electron microscope (SEM) – produce 3D images of specimen

19. Metric System Mass Length Volume Temperature gram (g) meter (m)
Decimal system of measurement in science
Scaled on multiples of 10
Mass
gram (g)
Length
meter (m)
Volume
liter (L)
Temperature
Celsius (°C)

20. Convert these measurements!
2000 mg = _______ g
5 L = _______ mL
16 cm = _______ mm
2500 m = _______ km
75 mL = __________ L
2 g (divide by 1000)
5000 mL (x1000)
160 mm (x10)
2.5 km (divide by 1000)
.075 L (divide by 1000)