Chapter 1

The Science of Biology

What were your first questions?

WHY?What?How?

What is Science?Science asks the same questions you did as

a young child.What is that?Why does it do what it does?How does that happen?What happens if …?

Science (Science (knowledge) is a ) is a process that investigates and process that investigates and attempts to understand and attempts to understand and

explain events in natureexplain events in nature.

Goal of ScienceGoal of ScienceProvide natural explanations for events

in the natural world.

Give examples of this

Use explanations to understand patterns in nature and to make useful predictions about natural events

Give examples of this

Since Science is a process, how do we go about doing “Science”?

The Scientific Method of course!!1. Ask a question based on an

observation

2. Do some research or infer

3. Propose a hypothesis

4. Conduct a controlled experiment

5. Collect data and make observations

6. Analyze data

7. Draw a conclusion

ObservingObserving and Asking QuestionsQuestions – Scientific investigations begin with observationobservation,

the act of noticing and describing events or processes in a careful, orderly way.

– Researchers observed that marsh grass grows taller in some places than others.

– A question is formed: Why do marsh grasses grow to different heights in different places?

Inferring & Forming a HypothesisHypothesis – Through observations and research, scientists

form inferencesinferences, or logical interpretations based on what is already known.

– These lead to a hypothesishypothesis, or a scientific explanation for a set of observations that can be tested in ways that support or reject it.

–

What kind of hypothesis could be made concerning the marsh grass growth?

– Researchers inferred that something limits grass growth in some places. Based on their knowledge of salt marshes, they hypothesizedhypothesized that marsh grass growth is limited by available nitrogen.

Design a Controlled ExperimentControlled Experiment• Design an experiment that keeps track of various

factors that can change, or variables– Only one variable is changed at a time

• Manipulative or Independent variableManipulative or Independent variable

– The variable that is observed and that changes in response to the independent variable is called the dependent variable dependent variable (also called the respondingresponding variable).

– All other variables should be kept unchanged, or controlled

• Controlled variableControlled variable

For the marsh grass experiment, identify each of the following variables:

• Manipulative or independent variable– Nitrogen fertilizer is added to the soil

• Control variables– Similar plant density, soil, plant type, sunlight,

amount of water, temperature…

• Dependent or responding variable– The rate at which the grass grows or its height.

Control and ExperimentalExperimental Groups An experiment typically has two groups:

1.An experimental group experimental group contains the independent variable

2.A control group control group is exposed to the same conditions as the experimental group except for one independent variable.

How will scientists keep track of experimental observationsand then analyze the results?

• Collecting DataData– Quantitative dataQuantitative data

• NumbersNumbers– How many blades of grass were found per meter?– How high, wide, long…was the grass?– How much nitrogen was found in the blades of grass?

– QualitativeQualitative• DescribeDescribe

– Which way did the grass grow?– What color was the grass?– Where there any other plants growing around it?

Recording the dataHow is data recorded?

Use charts, photos, drawings or graphs

This graph shows how grass height changed over time.

What might have been a source of error in this experiment?

The larger the sample size, the more reliably researchers can analyze variation and evaluate differences between experimental and control groups.

What conclusion could be drawn from the data collected?

Use experimental data as evidence to support, refute, or revise the hypothesis being tested, and to draw a valid conclusion.

Marsh grasses grew taller than controls by adding nitrogen.Marsh grasses grew taller than controls by adding nitrogen.

What if our hypothesis is not supported in our experiment?

– Close but no cigar. • Reevaluated and

revised the original hypothesis

• Make new predictions

• Redesign the experiment

Do you know where bees come from?

Recipe for Bees

1. Kill a bull during the first thaw of winter

2. Build a shed

3. Place the dead bull on branches and herbs inside the shed

4. Wait for summer. The decaying body of the bull produces bees

Words from a Roman poet about 2000 years ago

Spontaneous Generation Life arises from non-living matter or just suddenly

appear.Abiogenisis

Meat grows maggots Corn produces rats Bread breeds mold

So what do you think of this theory?

How are new living organisms produced?1. Question is stated Where do flies come from?2. Now we need to form a hypothesis

1. Francesco Redi (1668)Hypothesis: Flies lay small eggs on meat

that become maggotsSet up a controlled experiment to test his

hypothesisAnalysis: Found that by

keeping flies away from meat, no maggots appear

Conclusion: Maggots are the result of flies laying tiny eggs on meat that develop into

maggots

Variables

1. Controlled variable:

Jar, meat, location, temperature, time

2. Independent or Manipulative variable:

Gauze covering the meat jars

3. Dependant (responding) variable:

Whether maggots appear

Lazzaro Spallanzani 1776 • Designed experiment to show that life did not

arise spontaneously from food– Inferred that food spoils due to microbes in the food.

• Took 2 flasks with broth in them– Boils on but leaves it open– Boils the other but has it closed

Results – Only the closed one

prevented growth

What was wrong with what Spallanzani assumed?

No airEveryone knows that every living thing needs air to

liveWhose experiment solved Spallanzi’s air problem?

Louis Pasteur - 1859

Tested Spallanzani’s work by using a curved neck flask curved neck flask to prevent microbes from

entering flask but would let air in

Boiled broth in control and experimental flasks.

Result: No growth in curved neck flask.

Microbes collecting in bend

Pasteur’s broth in the curved necked flask stayed sterile for years until he tilted it and the airflow carried the microbes into the broth

ConclusionContamination is due to microbes in the air.

Spontaneous generation theory died here!!

Biogenesis is born!! All living things come from other living things.

Identify some scientific theories you have knowledge of.

1. Big Bang

2. Evolution

3. Relativity

A theorytheory is a well-tested explanation for a range of phenomena.

A lawlaw is a concise, specific description of how some aspect of the natural world is expected to behave in a certain situation such as the Gas laws

What is Biology?

Biology is the study of living things and how they interact with each other.

What are the characteristics of living things?

You and your partner are to brainstorm and ask yourselves the following.

• All living things have…

• All living things need…

• All living things can…

• All living things must…

What makes a living thing different from the desk you are sitting in?

• After you have brainstormed and edited your list, write them down on the chart on the next slide.

• When told to do so, go to each station in the back of the room, observe the specimen and check off if it has the characteristics you wrote down.

  Specimen

Trait

1 2 3 4 5 6 7 8 9 10

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What makes something living?Characteristics of LifeCharacteristics of Life

All living things…

1. …are made up of cells.

Unicellular or Multicellular.

2…need a constant flow of energy. Necessary for Metabolism Metabolism

All the chemical processes taking place in the organism including those that are needed for growthgrowth and those that are needed to break down break down molecules (such as digestion)

Some such as plants and some bacteria, make their own food from raw materials (Autotrophic)

Others such as animals, need to

process organic matter to obtain energy. (Heterotrophic)

3… maintain a stable, internal environment by responding to stimuli.

Maintain an internal steady state – Homeostasis.

Stimulus – anything that causes an organism to react/respond

Examples:• Increased heart rate when stressed• Goosebumps and shivering.• Pupillary response to light and darkness

– Let’s give this one a try

4. …Evolve

…as a group

• Evolution is a Evolution is a change in a species change in a species over timeover time

• Results from an species ability to adapt to changing conditions and reproduce.

5…grow and develop.

Your very first baby pictureProcess occurs by adding on more cells by cell

division (making more cells of the same kind) and cell differentiation (cells becoming different to

suit their various functions).

Red blood cell White blood cell Nerve cellsEasily flow through Change shape to Like a wire to capillaries squeeze through conduct electrical intracellular spaces impulses

6...can reproduce.

Adding on more cells or reproducing another organism

Passing on of genetic information (DNA and genes)

Not a necessary life process but needed for the continuation of the

species. Sexual (involves the fusion of two cells)

Asexual (involves only 1 cell dividing) reproduction.

7. …all living things are based on a universal genetic code

• DNAIt doesn’t matter if the

DNA of a bacterium or a human is analyzed, we all have the same 4 bases (ATCG) making up our DNA.

Measurements in Science

SI Measurements (Standard Increments)

aka: The Metric SystemUnit Abbreviation

Length Meters m Mass Gram gVolume Liter lTime Second sTemperature Celsius `C

Kelvin `KDensity Mass/Volume g/l or g/cm3

Prefixes Abbrevation Factor of base unitkilo k 1,000deci d .1 or 1/10centi c .01 or 1/100milli m .001 or 1/1000micro u .000001 or 1/1,000,000

Symbols of measurement

Metric Conversions

Convert: 5L = ______ml 1.025cm = _______ m .035um = ______ mm 2.5mm = ______um 7.2g = _____kg .017g = ______mg

Kilo Hecto Deka Meter Deci Centi Milli Micro

Liter

Gram

1. A recipe calls for 300ml of water. You add 0.25 L. Have you put in too much, too little or the right amount?

2. You are told that you need a jar with a volume of at least 150cm3. The label on the jar you find says 0.16L. Can you use it? Remember that 1cm3 = 1ml.

Lab Safety

• Contracts must be signed and returned to me immediately.

• All Science students must complete the Safety contract before entering into the lab

• Any student who does not have a lab safety contract signed will not be allowed to conduct labs.

The right tool is what is important

Where babies really come from

Our methodThe Way we do

things hereMeasure this

Watch it or the Safety Police will

get youThey're a What?

Life is a Wonderful Thing

Used to measure out a volume of a

liquid

Theory that life came from non-

living things

Method used to solve problems

Where the heating test tube should

be pointed

Basic units of measure for

Volume

If on fire, what should be done

Studies animalsNon-essential to the

individual's life characteristic

Vessel to hold and heat a liquid

Disproved the above using the

gauze covered jar

An educated guess

What shouldn't be on top of a

heating test tube

Basic units of measure for mass

Where to go if you get chemicals

in your eyesStudies plants

Type of reproduction found

in amoeba and hydra

Instrument used to pick up small

specimens

Also disproved it using the sealed boiled flasks of

gravy

What the above is based on

What should be on your eyes if

you are heating a test tube

How tall are you in meters

Three conditions when goggles would be worn

Studies bacteria and viruses

Keeping the body in a balanced state

Device used to observe small

specimens (not microscopic ones)

Father of Microbiology who

disproves this theory

Your 5 senses allows you to do

this

Where all the lab safety equipment are in the room

How many milliliters are in a

liter

What to do if you break a piece of

glassware

Looks at how living things

interact with their environment

Building up process

Measures the mass of an object

Special type of flask used by the

above

Keep these out of the above

How you should be dressed when doing a lab with an open flame

What part of a meter is a cm?

Where all glassware should

be on your lab tables

Studies how traits are passed from

one generation to the next

Breaking down process

Used on top of a glass slide with a

wet mount

What was the big difference between

Spallanzani's work and Pasteur's

The final answer to your problem

Caution should always be

exercised when working with this

What does um stand for?

How to pull out an electrical cord

from the socket

Studies the form of the human

body

The fact that you are getting scared about

taking this test means that you are

…

What units a graduated cylinder

measures in

Life comes from life

That which changes in an

experiment

The last thing you should always do after performing a

lab

1cm3 = ______What to use when

handling something hot

Studies how living things are

classified

All the chemical reactions in an

organism

The right tool is what is important

Where babies really come from

Our methodThe Way we do

things hereMeasure this

Watch it or the Safety Police will

get youThey're a What?

Life is a Wonderful Thing

Graduated cylinder

Spontaneous generation

Scientific methodAway from all people in lab

ml

Screamed that you are on fire, stop, drop and

roll and someone will bring a fire

blanket

Zoology Reproduction

Beaker or flask Redi Hypothesis A stopper g eye wash station Botony Asexual

Forceps SpallanzaniBasic research

and prior knowledge

Goggles </= 2m

Chemicals, heating

something, glassware

Microbiology Homeostasis

Hand lens Pasteur ObservationsOn the side of the

room1000ml in a m

Let the teacher know. Do not

touch itEcology Anabolism

BalanceSwan necked

flaskOpinions and

inferencesHair tied back and sleeves rolled up

1/100 or 100thAway from the

edge of your tableGenetics Catabolism

Cover slipPasteur allowed oxygen to get in

Conclusion Chemicals micrometerGently unplug by the plug, not the

cordAnatomy Irritability

ml Biogenesis VariablesClean up

everything and put all away

1mlTest tube holders,

tongs or mittsTaxonomy Metabolism