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Scientific Method and Experimental Design

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Presentation on theme: "Scientific Method and Experimental Design"— Presentation transcript:

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 Method
G 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)


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