INTRODUCTIONINTRODUCTION TO TO

BIOLOGYBIOLOGY

I.I. What is science?What is science?A.A. Science is the process that scientists Science is the process that scientists

use to understand the natural world. use to understand the natural world. B.B. Based on our sensesBased on our senses

II.II. What is biology?What is biology?A.A. The study of life.The study of life.

What process do we use to What process do we use to learn about sciencelearn about science??

The Scientific Method!

III.III. The Scientific MethodThe Scientific MethodA.A. State the problem or research questionState the problem or research question

ExEx: : Does Vitamin C help prevent sickness?Does Vitamin C help prevent sickness?

B. Gather background information on the B. Gather background information on the problemproblem

WhyWhy??C.C. Form a hypothesisForm a hypothesis

1.1. HypothesisHypothesis – an educated guess based on – an educated guess based on observationobservation

Ex: Ex: I think Vitamin C helps prevents I think Vitamin C helps prevents sickness because when I take it regularly I sickness because when I take it regularly I don’t get sick.don’t get sick.

D. Design an experiment to test your hypothesis

3 RULES TO FOLLOW:3 RULES TO FOLLOW:

1.1. Have a control Have a control a.a. ControlControl - the group that is - the group that is notnot exposed to exposed to

experimental variable experimental variable Ex: Ex: The group NOT given Vitamin C.The group NOT given Vitamin C.

2.2. Test only one variable Test only one variable D.D. VariableVariable – Something in an experiment that – Something in an experiment that

can be changedcan be changedEx: Ex: Vitamin C Vitamin C

u Use as many subjects as possible (30 Use as many subjects as possible (30 minimum)minimum)

E. Record and analyze dataData Table Example

1. Use tables and graphs to visually present your data; this allows you see patterns and draw conclusions

2. Graphing:E. Independent variable - factor in

experiment that scientist purposely changes; graph on x-axis (Ex: Vitamin C)

F. Dependent variable – factor in experiment that scientist wants to observe; changes in response to the independent variable; graph on the y-axis (Ex: Amount of times student got sick)

F.F. Form a conclusion (3 parts)Form a conclusion (3 parts)1.1. Address your hypothesisAddress your hypothesis

Use your data to Use your data to supportsupport or or rejectreject your your hypothesishypothesis

2. Error analysis2. Error analysis Sources of error that affected your Sources of error that affected your

resultsresults3.3. Suggestions for future experimentsSuggestions for future experiments

a. Specific changes to eliminate errorsa. Specific changes to eliminate errorsb. What improvements would you make?b. What improvements would you make?

u Repeat experimentRepeat experiment WhyWhy??

Designing an Experiment

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

IV.IV. Developing TheoriesDeveloping TheoriesA. After a scientist reports the results of

their experiment supporting their hypothesis…

1. Scientific theory explains things or events based on scientific knowledge resulting from many observations and experiments

2. Law is a time-tested concept that makes useful and dependable predictions about the natural world

What is an example of a scientific law?

V.V. Historical ExperimentsHistorical Experiments

A.A. Redi’s Experiment on Spontaneous Redi’s Experiment on Spontaneous GenerationGeneration

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.

PROCEDURE

Controlled Variables:jars, type of meat,location, temperature,time

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appearResponding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

B.B. Pasteur’s Test of Spontaneous GenerationPasteur’s Test of Spontaneous Generation

Pasteur’s experiment showed that all living things come from other living things

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms

CHARACTERISTICS OF CHARACTERISTICS OF LIFELIFE

I.I. All living things are called All living things are called organismsorganisms. In order to . In order to be considered an organism it must be:be considered an organism it must be:

A.A. Made of cellsMade of cells Organization of multicellular organismsOrganization of multicellular organisms

cellscells

tissuestissues

organism organism

organ systemorgan system

organsorgans

B. Capable of reproducing (sexually or asexually)C. Based on a genetic code (DNA) that determines

organism’s traits and limited lifespanD. Able to grow and developE. Need raw materials and energy

1. Metabolism – the breakdown of food into smaller molecules used to carry out life functions

F. Able to respond to stimuli (internal or external)1. Stimuli – something that causes a response

G. Homeostasis - Maintain stable internal environment despite changes in the internal and external environment

H. Evolve – change over time