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Chapter 1Chapter 1

The Science of BiologyThe Science of Biology

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What is Science?What is Science?

• ScienceScience -an organized way of using -an organized way of using evidence to learn about the natural evidence to learn about the natural world.world.

• Goals of science:Goals of science:– Investigate & understand the natural world.Investigate & understand the natural world.– Explain events in the natural world.Explain events in the natural world.– Make predictions.Make predictions.

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• Why science works:Why science works:

– Only deals w/ the natural world.Only deals w/ the natural world.

– Scientists collect & organize info in a Scientists collect & organize info in a careful, orderly way.careful, orderly way.

– Scientists look for patterns & Scientists look for patterns & connections b/t events.connections b/t events.

– Scientists explanations can be tested!Scientists explanations can be tested!

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Thinking Like a Scientist:Thinking Like a Scientist:

• To think like a scientist you must do To think like a scientist you must do a few things:a few things:– ObserveObserve

– Collect dataCollect data

– Make an inferenceMake an inference

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• Observations use senses to get info.Observations use senses to get info.– Info is called Info is called datadata..

• Data can be Data can be quantitativequantitative or or qualitativequalitative..

– QuantitativeQuantitative -counted or measured. -counted or measured.•Example: Example: there are 12 inches in a foot.there are 12 inches in a foot.

– QualitativeQualitative -can’t be counted. -can’t be counted.•Example:Example: “the scar on a manatee looks old” “the scar on a manatee looks old”

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• Once scientists have data, they make Once scientists have data, they make inferences.inferences.

• InferenceInference –a logical interpretation –a logical interpretation based on prior knowledge or based on prior knowledge or experience.experience.– Example:Example:

•You observe smoke coming from a building.You observe smoke coming from a building.– You You inferinfer that “ that “where there is smoke there is where there is smoke there is

firefire”.”.

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Explaining & Interpreting Explaining & Interpreting Evidence:Evidence:

• Example:Example:– Many people contract an unknown Many people contract an unknown

disease after attending a public concert.disease after attending a public concert.

– Public health officials will likely use the Public health officials will likely use the scientific methodscientific method to try & solve why this to try & solve why this happened.happened.

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• After making observations scientists After making observations scientists will propose 1 or more hypothesis.will propose 1 or more hypothesis.

• HypothesisHypothesis –a proposed scientific –a proposed scientific explanation for a set of observations.explanation for a set of observations.– It uses prior knowledgeIt uses prior knowledge– Logical inferencesLogical inferences– A creative imaginationA creative imagination

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• Possible hypothesis’ could be that:Possible hypothesis’ could be that:

– The disease spread from person to The disease spread from person to person via contact.person via contact.

– It spread by insect bites.It spread by insect bites.

– Or, it spread through air, food, or water.Or, it spread through air, food, or water.

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• A hypothesis A hypothesis mustmust be able to be be able to be testedtested..

• Hypothesis can be tested by:Hypothesis can be tested by:

– Controlled experimentsControlled experiments oror

– Gathering more dataGathering more data

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Science as a way of Science as a way of Knowing:Knowing:• Science is always changing.Science is always changing.

– New tools, techniques, & discoveries lead to New tools, techniques, & discoveries lead to new understandings.new understandings.

• Good scientists are skeptics:Good scientists are skeptics:– You question everything?You question everything?

• You must be open minded.You must be open minded.– Be open to new ideas & hypothesis.Be open to new ideas & hypothesis.

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Science & Human Values:Science & Human Values:

• Science is in many of the questions of Science is in many of the questions of today.today.– How should chemical wastes be disposed How should chemical wastes be disposed

of?of?•Who should be responsible for their disposal?Who should be responsible for their disposal?

– Should our electricity come from nuclear or Should our electricity come from nuclear or hydroelectric?hydroelectric?

– Should the info in your genes be kept Should the info in your genes be kept private?private?

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• All of these question involve science All of these question involve science in a way.in a way.

• But, science But, science can’tcan’t answer them. answer them.– Science makes recommendations.Science makes recommendations.– Society has the final decision.Society has the final decision.

•We consider our laws & moral principles, We consider our laws & moral principles, then we make a decision.then we make a decision.

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Section 2Section 2

How Scientists WorkHow Scientists Work

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Designing an Experiment:Designing an Experiment:

• Some old ideas about living things…Some old ideas about living things…– P. 8P. 8– Fig. 1.7Fig. 1.7

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Required Steps in a Good Required Steps in a Good Experiment:Experiment:

• Ask a question:Ask a question:– How, why?How, why?

• Forming a Hypothesis:Forming a Hypothesis:– Years ago people thought living things Years ago people thought living things

came from nonliving things.came from nonliving things.– This idea was called This idea was called spontaneous spontaneous

generationgeneration..

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• Ex:Ex:– mice spontaneously appear in stored grain mice spontaneously appear in stored grain – maggots spontaneously appear in meat.maggots spontaneously appear in meat.

• Spontaneous generation was a Spontaneous generation was a hypothesishypothesis..– Remember!Remember!

• Hypotheses must be tested.Hypotheses must be tested.

– The idea that maggots came from meat was The idea that maggots came from meat was tested by tested by Francesco RediFrancesco Redi..• To test it, Redi needed an experiment.To test it, Redi needed an experiment.• So, he devised a So, he devised a controlled expcontrolled exp..

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• Setting Up a Controlled Experiment:Setting Up a Controlled Experiment:

– Factors that can be changed in an exp. Factors that can be changed in an exp. are called are called variablesvariables..•Examples:Examples:

– Equipment usedEquipment used– Type of materialsType of materials– Amount of materialsAmount of materials– Temp.Temp.– LightLight– TimeTime

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• Hypotheses are tested in an Hypotheses are tested in an experiments. where only 1 experiments. where only 1 variable is changed at a time.variable is changed at a time.– This is called a This is called a controlled expcontrolled exp..– Controlled exp. have Controlled exp. have 22 types of types of

variables:variables:•Manipulated variableManipulated variable

– Variable that is deliberately changed.Variable that is deliberately changed.

•Responding variableResponding variable– Variable changes in response to the manipulating Variable changes in response to the manipulating

variable.variable.

– Refer to Redi’s Exp. Fig. 1-8Refer to Redi’s Exp. Fig. 1-8

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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.

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• Recording & Analyzing Results:Recording & Analyzing Results:

– Scientists keep records of their Scientists keep records of their observations, experements, or data.observations, experements, or data.

– These records are kept in:These records are kept in:• JournalsJournals•NotebooksNotebooks•Drawings Drawings Fig. 1-8Fig. 1-8•ComputersComputers

– Did Redi keep records?Did Redi keep records?•YesYes

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• Drawing Conclusions:Drawing Conclusions:– Evidence from a exp. either Evidence from a exp. either supportssupports or or

disprovesdisproves a hypothesis. a hypothesis.

– Did Redi’s exp. support his hypothesis?Did Redi’s exp. support his hypothesis?•Yes, it disproved the theory of Yes, it disproved the theory of spontaneous spontaneous

generation.generation.

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Repeating InvestigationsRepeating Investigations

• Often, scientists place their Often, scientists place their procedures & findings of an procedures & findings of an experiments in scientific journals.experiments in scientific journals.

• They do this so other scientists can They do this so other scientists can repeat their work.repeat their work.– Why?Why?

•Scientists can confirm or deny other Scientists can confirm or deny other scientists findings.scientists findings.

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Designing an ExperimentDesigning an Experiment

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

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• Let’s look at some scientists who Let’s look at some scientists who questioned Redi’s findings: questioned Redi’s findings:

• P. 11-13P. 11-13

– Needham Needham fig. 1-10fig. 1-10– Spallanzani Spallanzani fig. 1-10fig. 1-10– Pasteur Pasteur fig. 1-11fig. 1-11

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Needham’Needham’s s

ExperimenExperimentt

Fig. 1-10Fig. 1-10

SpallanzanSpallanzani’s i’s

ExperimenExperiment:t:

fig. 1-10fig. 1-10

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Pasteur's Experiment: fig. 1-Pasteur's Experiment: fig. 1-1111

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

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When Experiments Are Not When Experiments Are Not Possible:Possible:

• You can’t always do an exp. to test a You can’t always do an exp. to test a hypothesis.hypothesis.– When this happens you can do:When this happens you can do:

•Field studies & more observations Field studies & more observations – Enables us to study animal behaviorEnables us to study animal behavior– Fig 1-12Fig 1-12

•Medical studies & testingMedical studies & testing– Usually on volunteersUsually on volunteers

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How a Theory Develops:How a Theory Develops:

• TheoryTheory - -A very well tested explanation A very well tested explanation that unifies a broad range of observations.that unifies a broad range of observations.

– Examples of theories:Examples of theories:

• Theory of BiogenesisTheory of Biogenesis– All living things come from other living things.All living things come from other living things.

Verified by PasteurVerified by Pasteur

• Theory of EvolutionTheory of Evolution

• The Cell TheoryThe Cell Theory

• Big Bang theoryBig Bang theory

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• Some explanations in life need more Some explanations in life need more than one theory.than one theory.– Fig. 1-13Fig. 1-13– Examples:Examples:

•Theory of EvolutionTheory of Evolution

•Cell TheoryCell Theory

•Theory of Plate TectonicsTheory of Plate Tectonics

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Section 3Section 3

Studying LifeStudying Life

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• What is biology?What is biology?– study of lifestudy of life

– BiologyBiology –understanding the living world.–understanding the living world.

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Characteristics of Living Characteristics of Living ThingsThings• All living things share these characteristics:All living things share these characteristics:

1.1. made of cellsmade of cells2.2. reproducereproduce3.3. a genetic code (DNA)a genetic code (DNA)4.4. grow & developgrow & develop5.5. use materials & energyuse materials & energy6.6. respond to their environmentrespond to their environment7.7. maintain their internal env. (homeostasis)maintain their internal env. (homeostasis)8.8. evolveevolve

– Fig. 1-14Fig. 1-14

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• Made up of cells:Made up of cells:– CellCell –a collection of living matter –a collection of living matter

enclosed by a barrier that separates it enclosed by a barrier that separates it from its surroundings.from its surroundings.•Cell -the Cell -the smallest unit of lifesmallest unit of life..

•Cells -complex & highly organized.Cells -complex & highly organized.

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• Orgs. can be unicellular or Orgs. can be unicellular or multicellular.multicellular.– UnicellularUnicellular –single celled –single celled

•Ex: Ex: bacteriabacteria

– MulticellularMulticellular –many celled–many celled•Ex:Ex: humanshumans

– Fig. 1-15Fig. 1-15

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• Reproduction:Reproduction:– There are There are 22 types of reproduction: types of reproduction:

•AsexualAsexual– ““A” before a word means w/out. A” before a word means w/out. – The new org. has a single parent. The new org. has a single parent. – Offspring are exact duplicates of the parent. Offspring are exact duplicates of the parent.

(clones)(clones) – Fig. 1-16 Fig. 1-16 shows “budding” of a hydra.shows “budding” of a hydra.

•SexualSexual– Cells from 2 different parents unite to make the Cells from 2 different parents unite to make the

11stst cell of the org. cell of the org.

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• Based on Genetic Code:Based on Genetic Code:– Offspring resemble their parents.Offspring resemble their parents.– All living orgs. have DNA.All living orgs. have DNA.

•DNA DNA =Deoxyribonucleic Acid=Deoxyribonucleic Acid

•Determines the traits of every org. on Earth.Determines the traits of every org. on Earth.

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• Growth & Development:Growth & Development:– All living things grow to some extent.All living things grow to some extent.

•Growth = increase in size.Growth = increase in size.

•However, multicellular orgs. go through However, multicellular orgs. go through developmentdevelopment..

– Development involves cells dividing & becoming Development involves cells dividing & becoming specialized or “specialized or “differentiated”differentiated”..

– Ex: Ex: Stem cells can become:Stem cells can become: nerve cellsnerve cells skin cellsskin cells liver cellsliver cells brain cellsbrain cells

•Fig. 1-17Fig. 1-17

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• Need for Materials & Energy:Need for Materials & Energy:

– MetabolismMetabolism –set of chem. reactions –set of chem. reactions through which an org. builds up/breaks through which an org. builds up/breaks down materials.down materials.

– All orgs. need energy All orgs. need energy (E)(E)..•Plants, some bacteria, & most algae get E Plants, some bacteria, & most algae get E

from the sun.from the sun.

•Animals get E from food.Animals get E from food.

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• Response to the Env:Response to the Env:

– All orgs. sense & respond to stimuli in All orgs. sense & respond to stimuli in their env.their env.

– StimulusStimulus –a signal to which an org. –a signal to which an org. responds.responds.

•Ex:Ex: plant seeds respond to warmth & water. plant seeds respond to warmth & water.

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• Maintaining Internal Balance:Maintaining Internal Balance:

– HomeostasisHomeostasis –process by which orgs. –process by which orgs. maintain a maintain a relativelyrelatively stable internal env. stable internal env.•Ex: Ex: home heating/cooling system.home heating/cooling system.

•Another example, the bird in Another example, the bird in fig. 1-19.fig. 1-19.– When it is cold it hunches down & adjusts its When it is cold it hunches down & adjusts its

feathers for maximum insulation.feathers for maximum insulation.

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• Evolution:Evolution:

– EvolutionEvolution – –process by which modern process by which modern orgs. have descended from ancient orgs. orgs. have descended from ancient orgs. over long periods of time.over long periods of time.

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Characteristics of Living Characteristics of Living Things:Things:Characteristic ExamplesLiving things are made up of units called cells.Living things reproduce.

Living things are based on a universal genetic code.

Living things grow and develop.

Living things obtain and use materials and energy.

Living things respond to their environment.Living things maintain a stable internal environment.

Taken as a group, living things change over time.

Many microorganisms consist of only a single cell. Animals and trees are multicellular.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Flies begin life as eggs, then become maggots, and then become adult flies.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.

Leaves and stems of plants grow toward light.

Despite changes in the temperature of the environment, a robin maintains a constant body temperature.

Plants that live in the desert survive because they have become adapted to the conditions of the desert.

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Branches of Biology:Branches of Biology:

• Some branches of biology:Some branches of biology:– Zoology Zoology –study animals–study animals– BotanyBotany-study plants-study plants– PaleontologyPaleontology-study of ancient life-study of ancient life– Molecular/Cell biologists-Molecular/Cell biologists- study of the study of the

smallest life forms.smallest life forms.– Population biologists & ecologistsPopulation biologists & ecologists –study –study

of the largest systems on Earth.of the largest systems on Earth.

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Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

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Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

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Biology in Everyday Life:Biology in Everyday Life:

• Read this section in class…Read this section in class…

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Section 4Section 4

Tools & ProceduresTools & Procedures

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A Common Measurement A Common Measurement System:System:• Scientists use the metric system for data & Scientists use the metric system for data &

performing experiments.performing experiments.– Metric system:Metric system:

• -a decimal system of measurements w/ units that are -a decimal system of measurements w/ units that are based on based on multiples of 10multiples of 10..

• International System of UnitsInternational System of Units–revised version of the –revised version of the metric system.metric system.

– Abbreviated as Abbreviated as SISI– Les Systeme International d’unites (French)Les Systeme International d’unites (French)

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Common Metric Units

Length Mass1 meter (m) =100 centimeters (cm)

1 meter = 1000 millimeters (mm)

1000 meters = 1 kilometer (km)

1 kilogram (kg) = 1000 grams (g)

1 gram = 1000 milligrams (mg)

1000 kilograms = 1 metric ton (t)

Volume Temperature1 liter (L)= 1000 milliliters (mL)

1 liter = 1000 centimeters (cm3)

0 ºC = freezing point of water

100 ºC= boiling point of water

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Analyzing Biological Data:Analyzing Biological Data:

• Once scientists collect data, they put Once scientists collect data, they put it in tables & graphs.it in tables & graphs.– Graphs make it easier to analyze data.Graphs make it easier to analyze data.

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Fig. 1-24, p. 25Fig. 1-24, p. 25

Water Released & Absorbed by TreeWater Released & Absorbed by TreeWater Released and Absorbed by Tree

TimeAbsorbedby Roots

(g/h)

Releasedby Leaves

(g/h)8 AM

10 AM

12 PM2 PM4 PM6 PM8 PM

5

2

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641

1

12

17

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Water released by leaves

Water absorbed by roots

Rel

ati

ve

Rat

es

(g/h

)

20

Time

0

15

10

5

8 AM 10 AM 12 PM 2 PM 4 PM 6 PM 8 PM

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• Today, computers help analyze data.Today, computers help analyze data.– Examples:Examples:

•They help determine structure of molecules.They help determine structure of molecules.

•They enable us to look through a DNA They enable us to look through a DNA molecule.molecule.

•Computers gather satellite data.Computers gather satellite data.– Global climate changesGlobal climate changes

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Microscopes:Microscopes:

• MicroscopeMicroscope -device that magnifies -device that magnifies images of structures.images of structures.

• There are There are 22 main types of main types of microscopes:microscopes:– Light microscopeLight microscope– Electron microscopeElectron microscope

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• Light Microscopes:Light Microscopes:

– Most commonMost common– Can magnify up to 1000x.Can magnify up to 1000x.

– Compound light microscopesCompound light microscopes –uses light –uses light to pass through the specimen & uses 2 to pass through the specimen & uses 2 lenses to form an image.lenses to form an image.•We use the light microscope to:We use the light microscope to:

– Study dead orgs. & their parts.Study dead orgs. & their parts.– Observe tiny orgs. & cells while alive.Observe tiny orgs. & cells while alive.

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• Electron Microscopes:Electron Microscopes:

– When scientists look at even smaller When scientists look at even smaller objects they rely on objects they rely on Electron Electron Microscopes Microscopes (EM)(EM)..

•Electron microscopes use a Electron microscopes use a beam of beam of electronselectrons, rather than light, to produce , rather than light, to produce images.images.

– The best EM can make images 1000x more The best EM can make images 1000x more detailed than a light microscope.detailed than a light microscope.

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• There are There are 22 types of EM: types of EM:

– Transmission EM (TEM)Transmission EM (TEM)– Scanning EM (SEM)Scanning EM (SEM)

•The TEM produces images that are a cross The TEM produces images that are a cross section of an object.section of an object.

•The SEM produces 3D images of an object.The SEM produces 3D images of an object.

•There is a negative to the use of EM’s.There is a negative to the use of EM’s.– You cannot view living thingsYou cannot view living things..

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TEM

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SEM

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Lab Techniques:Lab Techniques:

• Biologists use many ways to study Biologists use many ways to study cells.cells.

• 22 common ways are:common ways are:– Cell culturesCell cultures– Cell fractionationCell fractionation

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• Cell cultures:Cell cultures:

– A group of cells grown in a nutrient A group of cells grown in a nutrient solution from a single original cell.solution from a single original cell.

– Cell cultures are used for:Cell cultures are used for:•Testing cell responses under controlled Testing cell responses under controlled

conditions.conditions.

•Studying the interactions b/t cells.Studying the interactions b/t cells.

•Selecting specific cells for further study.Selecting specific cells for further study.

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• Cell fractionation:Cell fractionation:

– The technique in which cells are broken The technique in which cells are broken into pieces & the different cell parts are into pieces & the different cell parts are separated.separated.

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Working Safely in Biology:Working Safely in Biology:

• Always follow safety rules.Always follow safety rules.

• Wash hands after every scientific Wash hands after every scientific activity.activity.

• Always wear protective gear when Always wear protective gear when called for.called for.