1a Bio SB Unit 1 1-13

Unit 1: Biology andthe ScientificMethod

Unit 1: Biology and the Scientific Method 3

Vocabulary

Study the vocabulary words and definitions below.

apparatus ........................................ the equipment or tools needed for aspecific task (pl. apparati)Example: forceps are dissecting apparati

biologist .......................................... a person who studies the science of life

biology ............................................ the study of living things; the science oflife

conclusion ...................................... the logical evaluation of a theory asshown by data from an experiment orevidence from experience

control ............................................. that part of the experiment where thevariable is not changed

data .................................................. information recorded on all aspects ofan experiment

experiment ..................................... an activity designed to test a hypothesis

fact ................................................... something known with certainty

hypothesis ...................................... a statement that may explain a group ofrelated observations (pl. hypotheses)

4 Unit 1: Biology and the Scientific Method

metric system ................................. an international system of measurementbased on multiples of 10

microscope ..................................... an instrument with a series ofmagnifying lenses for inspecting objectstoo small to be seen in detail by theunaided eye

observation ..................................... something learned through the sensessight, hearing, taste, smell, or touch

problem ........................................... a question that can be answered throughobservation and experimentation

science ............................................. the system by which data is gathered,problems are solved, and theories aredeveloped; it seeks to describe the scopeand function of the universe

scientific method ........................... a logical, orderly way to solve a problemor answer a question usingexperimentation and observation

superstition .................................... an untested or untestable belief upheldby faith in magic or chance

theory .............................................. a generalized explanation of eventsbased on the conclusions of severalexperiments made by several peopleover a long period of time

variable ........................................... a condition that can be changedthroughout the experiment to test thehypothesis


Introduction

Biologists are people who study the science of life. Science provides away to ask questions about the world around us and to find reliableanswers. Biologists and other scientists use a system to investigatequestions that is called the scientific method. Though this term maysound rather technical, all of us use the scientific method to some extenteach day as we make sense of information.

Science is an exciting exercise because it gives us a way to investigate thethings that puzzle us. Biology, as the science of life, involves everythingaround usthe trees outside the window as well as the fingernail on yourlittle finger. Its more than a subject that begins and ends as you open andclose this book. So crank up that scientific method and look around: Askwhy, find out how get the facts!

The Scientific Method: What Is It?

People once used superstition and myth to explain everyday happeningssuch as thunder (the gods must be angry) to the origins of tadpoles(they come from the mud). People now try to explain such mysterieswith the help of the scientific method. The scientific method is a way tologically answer questions.

The scientific method involves several steps. First, you identify a problemor an area of interest. You state it as a question that you think you cananswer through further investigation. Second, you gather moreinformation about the problem. Third, you construct a statement that youthink explains what you have observed. This statement is called ahypothesis. Fourth, you carry out an experiment to test your hypothesis.You must make careful observations ofthe results of your experiment. Usingthese, you draw a conclusion that issupported by your observations. Itis important to note a few pointsabout conclusions. Conclusionsare based on observations fromexperiments. They are not basedon observing the entireuniverse. For that reason,

Draw conclusions andreport the results.

Identify the problem.

Gather information on the problem.

Form a hypothesis.

Experiment to test thehypothesis.


conclusions can do only a few things. A conclusion can show a hypothesisis untrue. Conclusions cannot prove a hypothesis is true. At first, this mayseem strange, but remember:

conclusions can prove a hypothesis isuntrue

conclusions can support a hypothesisor state it seems likely

conclusions can never prove ahypothesis is true

Remember

Whatever conclusions you reach, the conclusion is only a part of thescientific method. It relies on the rest of the scientific method beingperformed properly.

1. Identify the problem.2. Gather information on the problem.3. Form a hypothesis.4. Experiment to test the hypothesis.5. Draw conclusions and report the results.

Remember, the scientific methodinvolves the following five steps:

Though its easy to laugh at the superstitions of people from long ago,strange notions based on mistakes in thinking are not limited to the farpast. In fact, when we look at some of the wrong conclusions people havedrawn from their observations, even recently, it gives us even more reasonto apply the scientific method very carefully to problems we face today.


The Scientific Method in Action

The problem of yellow fever is a good example of how the scientificmethod was used to fight myth and superstition. Yellow fever is a diseasethat used to kill thousands of people, particularly in the southern UnitedStates and throughout Central and South America. Large numbers ofpeople died in outbreaks of this disease as recently as the early 1900s.Until the turn of the century, people didnt know where this disease camefrom. Some burned fires in an effort to clean the air, thinking it somehowcame from bad air. In Jacksonville, Florida, authorities would fire cannonsacross the St. Johns River, hoping the vibrations would chase the diseaseaway.

However, in collecting information on yellow fever, some scientistsnoticed that outbreaks of the disease mainly occurred in swampy areasareas with lots of mosquitoes. When these scientists presented theirhypothesis that mosquitoes carried the disease, some peopleincludingother scientiststhought this was such a stupid idea that they slashedtheir window screens to show their disbelief in this explanation.

As an experiment for testing their hypothesis, the scientists suggestedwidespread mosquito extermination. The number of mosquito bites wasthe variable they wanted to change. Areas where the number of mosquitobites remained the same served as a control for their experiment. Aspeople wiped out mosquitoes by draining swamps and other placeswhere they breed, there were fewer outbreaks of the disease.

From this data, many formed the conclusion that mosquitoes were indeedthe carriers of the disease. Using this conclusion to investigate the diseasefurther, scientists finally discovered that one specific type of mosquito

carries a virus that causes yellow fever. From thisand other scientific investigations, biologists

have come up with the theory thatcommunicable diseases are caused by livingorganisms, not bad air or othersuperstitions. A theory is a generaldescription of activity based on manysupported hypotheses.


Talking About It

From this story its obvious that open discussion between scientists is veryimportant in solving scientific problems. What if the scientists whobelieved that mosquitoes were the carriers of yellow fever had beenunable to present their opinion and test their hypothesis? Even thoughmany people thought they were crazy, some pursued their hypothesisusing the scientific method. The story of yellow fever is an importantlesson in how even supposed experts argue among themselves and howevery hypothesis has value until it is proven wrong.

Scientists present their work for discussion by publishing it in scientificjournals. You may have heard of the New England Journal of Medicine or theAmerican Naturalist. In these journals, scientists describe their experimentsclearly and present their measurements in the metric system, a system ofmeasurement that is used worldwide for science (see Metric Tables, pages329-330). This gives other scientists a chance to read about new work anddiscoveries to decide whether the scientific method was used correctly toform conclusions. Other scientists may even go so far as to repeat anexperiment to see if they get the same results that were reported. In thisway scientists can check each other's work.

The scientists who investigated yellow fever were exploring a newproblem. As we mentioned above, other scientists investigated previousresults. Since the conclusion of the investigation into yellow fever, otherexperiments have been conducted. These theories have been used to makepredictions. Another reason to investigate is to check how well a theorypredicts. Occasionally, two theories may be proposed. In this case,scientists investigate to see which theory best fits the results.

?Theory One Theory Two

Yellow Fever

?mosquitoes were

to blamebad air was to

blame

With yellow fever, we could consider that there were two theories. Onetheory said bad air was to blame, and another said mosquitoes were theculprits. We have learned that the mosquito theory seems to have been


better. As we mentioned before, though, no theory is ever proven true. Itis possible (though highly unlikely) that some new theory may betterdescribe how people catch yellow fever. This is one of the most importantideas in science. No matter how well one theory may work, another maywork better. It may describe more or predict more. This process leads tothe occasional discarding of theories.

What happens when such a theory is discarded? One result is that wehave a better understanding of the universe. Most such changes are small.As we saw with yellow fever, sometimes the changes are drastic. As timepasses, we gain a more refined view of the world and universe. Scientistsdon't think they will ever achieve absolute truth, but they will continue toimprove upon what we know. Each day we get a better picture of ourworld.

Its important that each of us use the scientific method when we read thenewspaper each day. Does the news seem to present the facts fairly? Doesthe writer seem to jump to conclusions that disagree with the data? Whatabout advertisements? Does a television cost any less if you rent to owninstead of saving up your money and paying for it all at once?

Experimental Equipment

Biologists and other scientists have come up with a variety of tools. Thesedifferent tools, called apparati, are for testing their hypotheses throughexperiments. Youre probably familiar with one common apparatus, themicroscope. The computer is another apparatus. There are some itemsthat you will have to practice to know and use well. Basic equipment isdescribed on page 11, Scientific Apparatus.

The microscope is one of the most important tools inbiology because it increases our powers of observation.Though the microscope may seem like a rather

complicated machine, its really just a set ofmagnifying lenses. It magnifies both through the lensof the eyepiece and a second lens nearer the thing

you're examining. When you use a microscope,you prepare the thing you wish to observethespecimenby placing it on a glass slide. Then,when the slide is placed on the microscope stage,light passes through both the specimen and

through the lenses. The image you see ismagnified many times.


eyepiece

low-powerobjective lens

high-powerobjective lens

stage clips

stage

base

lightor mirror

diaphragm

coarseadjustmentknob

fineadjustmentknob

arm

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Parts of the Microscope


5045403530252015105 Laboratory Graduated A

voirdupois/ Metric Scale

droppers petri dish beaker testtube

thermometer

dissecting scissors

scalpel

probe graduatedcylinder

microscopeslide

balance

forceps

hand lens

flask

mortar andpestle

safety goggles

metricruler

The other lab equipment you will be using, for the most part, includescontainers for mixing and tools for measuring. Become familiar with theirnames so that youll be comfortable using them in experiments.

Scientific Apparatus


Safety in the Lab

Working safely usually means using common sense. Because most of us aresensible people, its easy to think we know all we need to know aboutsafety. However, thats not necessarily the case in a laboratory setting. Thelaboratory is at least a little bit unfamiliar to most students. Therefore,situations might come up where the sensible thing to do isnt obvious.Thats why its important to look at safety rules developed by people whoare used to working in laboratories and have experience with the dangersthat might arise in a laboratory.

Read the Safety Guidelines below. Learn them well enough that theybecome second nature when youre working in a lab. They will save youfrom mistakes that have hurt other people as they were working. Theserules are designed to protect you.

1. Read and follow all directions while working in the laboratory.2. Wear protective gear, such as aprons, at all times. Wear goggles

when working with dangerous or hot chemicals, or any time your teacher instructs you to do so.

3. NEVER taste or directly inhale chemicals. Waft chemicals to smellthem. Your teacher can show you how.

4. DO NOT bring food or drink into the lab.5. Wash hands thoroughly after each lab.6. DO NOT rub eyes or put hands in mouth.7. Dress in a way that helps you work safely and efficiently in the

lab. Tie your hair back. Wear cottonit doesnt catch fire as easilyas nylon or polyester. Always keep your shoes on while in the lab. Roll up long or loose sleeves.

8. DO NOT look directly down into the mouth of a filled test tube.DO NOT point the mouth of a filled test tube at another student.Liquid can splash into eyes.

9. DO NOT perform any experiments unless the instructor is in the room.

10. Report ALL minor and major accidents to your instructor.11. Know the location of the safety shower, eye wash, and fire blanket.

Know how to use these important pieces of safety equipment.12. Turn off gas burners and the gas outlets when no one is using

them. NEVER leave a lit burner unattended.13. Keep lab tables clean and neat to prevent accidents. Wipe all

areas at the end of the lab.14. MAKE SAFETY A HABIT!

Safety Guidelines


Summary

The scientific method gives us a framework for posing and answeringquestions. It consists of the following steps:

1. Identify the problem.

2. Gather information on the problem.

3. Form a hypothesis.

4. Experiment to test the hypothesis.

5. Draw conclusions and report the results.

Open discussion allows scientists to compare the results of theirexperiments. A commitment to review by other scientists is essential.Scientists use the metric system as a standard system of measurement forall experiments.

Scientists conduct investigations on new problems to check old theories, totest how well a theory predicts, and to compare theories. Theseinvestigations sometimes lead to large changes; more often, changes aresmall. These changes take place because a conclusion is never proven true.Sometimes theories are discarded. The result of all this is an improvedview of the world.

Scientific equipment, particularly microscopes, is useful in studyingbiology. Practicing safety in the laboratory protects you, your classmates,and the scientific equipment you use.

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Careers in Biology

Laboratory technicians assist in the operation ofscientific labs. These labs can vary widely to includemedical research labs, chemistry labs, orpharmaceutical labs. The work done by a technicianmay be overseen or monitored by scientists, doctors,or others who direct the investigation. Sometechnicians receive on-the-job-training while othersmay take some college course work to prepare. Theneed for laboratory technicians seems to be growing.

Laboratory Technician

1a Bio SB Unit 1 1-13

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