The Science of Biology

Biology 392

Observing the WorldObserving the World

If you are a thinker, you question things you observe and may not understand and you

try to find an answer. There are many ways to find these answers. If you are a scientific thinker you find your answer

using the scientific method.Example:

Why is the sky blue?

1-1 What is science?

an organized way of using evidence to learn about the natural world

It also refers to the body of knowledge that scientists have accumulated over time. It is not based on belief or faith, magic, or

legend but on actual evidence. It is concerned with the natural world, not the supernatural world.

What is Biology?

Biology is a specific field of science that studies

life

Important Skills used When Doing Science:

Observing- process of gathering information using your senses in a careful,

orderly way

Inferencing- making a logical interpretation based on prior knowledge or experience

Good Scientists... are skeptics: They question existing ideas and new hypotheses. are open-minded: They are always willing to consider new ideas

when evidence demands it rely on basic natural laws: They understand that the universe

functions as a system of interacting processes. repeat experiments: through an immense amount of research a

certain hypothesis might become so well-supported that scientists consider it a theory (example: biogenesis).

keep up with new knowledge gained through research: They continually revise and re-evaluate their ideas. NOTHING IS “FACT”.

*Many questions you have now or will have in the future involve science. You must understand science to make intelligent decisions about such issues.

How is Science Done? Scientists use the scientific method. When

scientists have a question about something in the world they use this method to find an answer:

State the Problem or Question Research State a hypothesis Design an experiment with a

control group, constants and variables Analyze data/ results Conclusion or Summary

1. State the Problem or Question

What have I observed?

What do I want to know?

2. Research

Has anyone asked this before?

Did they discover an answer?

How did they go about looking for an answer?

What other things do I need to understand to answer my question?

3. Form a Hypothesis

Based on the research you have done, write a possible answer or solution – your best

educated guess – to your question.

4. Design an Experiment Control Group: Part of your experiment that is

not varied in anyway. You can compare your test groups to this set standard group.

Independent variable- The change/difference you make in the experiment (the thing you are testing). Also called manipulated variable

Dependent variable- The differences that result from the experiment, the resulting effect. Also called responding variable.

Constants- Things in the experiment that do not change, kept exactly the same for each test group so they do not affect the results.

5. Data/Results

It is easier to understand the data if it is put into a table and/or graphed.

Make sure all data is clearly labeled. Charts and graph should always include units and titles.

When graphing the independent variable should be on the x axis and the dependent variable should be on the y axis.

6. Analysis

What happened?

What was expected? What was unexpected?

What trends did you notice in the data?

7. Conclusion or Summary

Indicate whether or not the data supports the hypothesis and explain why or why not.

Suggest possible improvements to the experiment.

Suggest further avenues of research or uses for the information discovered.

Learning Checkpoint What is inferencing? What are the steps of the scientific method? In which step would you find charts and graphs? What is the difference between an independent

variable and a dependent variable? What is the purpose of a control group? What does it mean to have a controlled experiment?

1-2 An Example of Science at Work

Observed: sometimes organisms just “arose” from nonliving things: eg. maggots came from meat.

The Question: How do new living things come into being? Hypothesis: In some cases, nonliving objects can spontaneously

generate living organisms.

1st Experiment- 1668, Francesco Redi: Meat in covered and uncovered jars proposed a new hypothesis: The maggots came from eggs left by flies

on the meat that were too small to see. Concluded: Maggots came from flies.

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 appear

Responding Variable: whether maggots appear

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

Redi’s ExperimentRedi’s Experiment

Science continues...New Ideas with new discoveries

New discovery!- tiny microorganisms (discovered by Anton van Leeuwenhoek)

2nd Experiment- Mid 1700s, John Needham: Repeats Redi’s experiment. His hypothesis: Spontaneous generation can

occur under the right conditions. Result: microorganisms appear in sealed flask

of boiled gravy.

Science Experiments are always repeated:

3rd Experiment- Lazzaro Spallanzani: Thinks Needham did not boil gravy long enough to

kill existing microorganisms. Results: When left exposed to air, microorganisms

will appear in boiled gravy. He concluded that microorganisms could not come

from gravy but appeared instead from microorganisms existing in the air.

Spallanzani’s TestsSpallanzani’s Tests

Gravy is boiled. Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

Needham tried first but didn’t bring

gravy to hot enough temperature.

New Question: Is air the “life force”?

4th Experiment- 1864, Louis Pasteur: Set out to dismiss the notion that the “life

force”, air was needed to generate life. Used curved neck on flask so air could get

in but organisms would not. Concluded that all living things can only come from living things. This has been tested over and over and is now considered a theory called biogenesis.

Learning Checkpoint

Did all 4 scientists use good scientific thinking and a controlled experiment?

What is spontaneous generation? What was the point of the “swan neck”

Pasteur added to his flask? What is biogenesis?

1-3 Studying Life (Biology)

What is considered alive?

living things... are made of cells reproduce are based on a universal genetic code grow and develop obtain and use materials and energy respond to their environment Maintain a stable internal environment

(homeostasis) Change over time

Studying Life in Various Ways Branches of Biology

Divided into fields based on the type of life or particular perspective

Examples of type of life: Zoologist study animals, Botanist study plants, Microbiologists study bacteria and other small organisms

Examples of perspective: Paleontologists study ancient life, Embryologists study newly forming life

Studying Life at Various Levels

Bioethics

What is bioethics?Can you think of any ethical

issues that science must face?

1-4 Tools and Procedures used in Biology

Science ALWAYS uses the METRIC SYSTEM to make measurements

Why? Base units: Length- meter, Mass- gram, Volume-

liter, Temp. Celsius Conversions: 1 mile = _________m

1 pound= ________ kg

1 cup = ________ mL

Microscopes

Compound light microscope Series of lens that use light to magnify image (usually 1000x) can study dead or alive organisms, no smaller than .2 microns Have been used in conjunction with chemical stains (to identify

parts) and fluorescent dyes (to create 3-D images)

Electron microscope Use beams of electrons to produce images, up to 1000x more

detailed than light microscope images Cannot observe living specimens (slides must be in a vacuum) Two main types: SEM- scanning electron microscope and

TEM- transmission electron microscope

Learning Checkpoint What are the 8 characteristics of life? What is the difference between a community

and a population? What metric units would you use to measure

the amount of water in a pool?

Your height? Your weight? The weight of a paper clip?

The Microscope