Scientific Method

The Nature of Science

Cures for disease Explains what our world is like Solve environmental problems Use and discover new technology

Biologist reason in 2 ways:

1. Deductively 2. Inductively

Deductive Reasoning

Applies general principles to predict specific results.

Example: determining the species of a specimen from its characteristics

If A then B type of reasoning, used in math and philosophy

Inductive Reasoning:

Logic flows from the specific to the general Example: Cats have fur, dogs have fur, and

every mammal you observe has fur, then you may infer that all mammals have hair.

How Science Is Done

1. Question or Observation 2. Hypothesis 3. Controlled Experiment 4. Make Predictions 5. Develop Theory Hypotheses are accepted or rejected based

on experimental results.

Establishing Controls (variables)

Independent Variable: the investigator manipulates (fertilizer on plants)

Dependent Variable: the outcome or results (did the plants grow taller, greener or faster than the group without fertilizer)

Using Predictions

A hypothesis is most useful when it makes predictions, because predictions provide a way to test the validity of the hypothesis

If experimental results are inconsistent with the predictions then the hypothesis must be rejected.

If experimental results are consistent with the predictions then the hypothesis must be accepted.

Fig. 1.4

Observation

Question

Experiment

Hypothesis 1Hypothesis 2Hypothesis 3Hypothesis 4Hypothesis 5

Potentialhypotheses

Remainingpossiblehypotheses

Last remainingpossible hypothesis

Rejecthypotheses

1 and 4

Rejecthypotheses

2 and 3Experiment

Hypothesis 2Hypothesis 3Hypothesis 5

Hypothesis 5

Predictions

Predictionsconfirmed

Experiment 1 Experiment 2 Experiment 3 Experiment 4

Fig. 1.4(TE Art)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Basic vs Applied Research

Basic research expands the boundaries of what we know and is usually performed at Universities

Applied research is conducted by scientists in industry. Example food additives, new drugs, testing environmental quality

Fig. 1.A

Read page 7

How Biologists

Do Their Work

Homework

https://glacier.gc.maricopa.edu/biology/scientific_method/index.cfm

Do this activity on your computer! Click continue to start Enter your name or initials Do the tutorial part first then the cricket

experiment This is a lot of fun!