What is a Scientist?

What is a Scientist?Ms. Moore08/17/12

Albert EinsteinphysicistStephen Hawkingcosmology and quantum gravityScientists areScientist: a person who is studying or has expert knowledge of one or more of the natural or physical sciences

Who are your favorite scientists?

How many scientists are in this room?

What is Science?Science: organized way of using evidence to learn about the natural world

The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions.

Thinking Like a ScientistObservation: the process of gathering information about events or processes in a careful, orderly way.

Data: the information gathered from observations.Quantitative data: expressed as numbers, obtained by counting or measuring.Qualitative:

Inference: logical interpretation based on prior knowledge or experience.

Explaining EvidenceHypothesis: a proposed scientific explanation for a set of observations.These are generated by scientists using prior knowledge, logical inference, and informed, creative imagination.There can be more than one hypothesis for a question.Designing an ExperimentScientific Method : Asking a QuestionForming a HypothesisSetting up a Controlled ExperimentControlled experiment: constantManipulated/Independent variable: deliberately changed Responding/Dependent variable: changes in response to manipulationRecording and Analyzing ResultsWritten records of observations and data.Drawing a ConclusionExplanation of observations.Spontaneous GenerationSpontaneous Generation: Francesco RediObservation: Flies land on meat that is left uncovered, then maggots appear.Hypothesis: Flies produce maggotsProcedure: Covered and Uncovered JarsControlled variables: jars, type of meat, location, temperatureManipulated (Independent) variable: gauze covering that keeps flies away from meatResponding (Dependent) variable: whether maggots appearConclusion: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur

ReplicationExperiments are often repeated by other scientists to ensure accuracy of experimental procedures and results

A key assumption in science is that experimental results can be reproduces because nature behaves in a consistent manner

Needham vs. SpallanzaniSpallanzani improved Needhams work by observing work of others (Redi); however, air was omitted and could not disprove spontaneous generation. How did Pasteur finally disprove spontaneous generation?

When experiments are not possibleIt is not always possible to do an experiment to test a hypothesis:Ethical issues of humansEx: Does this chemical cause cancer in humans?Disruption of a natural systemEx: How do animals in the wild interact with each other?

TheoryAs evidence from numerous investigations builds up, a particular hypothesis may become so well supported that scientists consider it a theory.

In science, theory applies to a well tested explanation that unifies a broad range of observations.Biogenesis: generating from life

Activity: Scientific MethodStudents will work with lab groups to understand the scientific method. Each group is assigned a story and they must Ask a questionForm a hypothesisDesign an experimentIncluding all variables that would be testedStudying LifeBiology: the science that employs the scientific method to study living things.

Living Things:Made up of cells: the smallest until of an organism that can be considered alive.ReproduceSexual reproduction: cells from two different parents unite Asexual reproduction: single parent produces offspring that are identical to itselfBased on a universal genetic code written in DNAGrow and developDifferentiation: cells begin to look different from one another and perform different functions

Obtain and use material and energyMetabolism: combination of chemical reactions through which an organism builds up or breaks down materialRespond to their environmentStimuli: a signal to which an organism respondsLiving things maintain a stable internal environmentHomeostasis: organisms need to keep conditions inside their bodies as constant as possibleLiving things evolve

Levels of OrganizationMolecules: groups of atomsCells: smallest functional unit of lifeGroups of Cells: tissues, organs, organ systemsOrganism: individual living thingPopulation: group of organisms of one type that live in the same areaCommunity: populations that live together in a defined areaEcosystem: community and its non-living surroundingsBiosphere the part of Earth that contains all ecosystemsTools and ProceduresMost popular system of measurement among scientists: metric system

Metric System: decimal system of measurement whose units are based on multiples of 10

LengthLength is the distance from one point to another

What can we use to measure length in the lab?

Common Metric Units (meter = slightly longer than a yard)1 meter (m) = 100 centimeters (cm)1 meter = 1000 millimeters (mm)1000 meters = 1 kilometer (km)

MassThe amount of matter in an object is defined as mass.

How could we measure mass in lab?

Common Metric Units (1 gram = 1 paperclip)1 kilogram (kg) = 1000 grams (g)1 gram = 1000 milligrams (mg)1000 kilograms = 1 metric ton (t)

VolumeVolume is the amount of space an object takes up.

How is volume measured?

Common Metric Units1 liter (L) = 1000 milliliters (mL)1 liter = 1000 cubic centimeters (cm3)

TemperatureTemperature is used to measure hotness or coldness.

How is temperature measured?

Common Metric Units0C = freezing point of water100C = boiling point of water

Metric-English Equivalents2.54 centimeters (cm) = 1 inch (in.)

1 meter (m) = 39.37 inches (in.)

1 kilometer (km) = 0.62 miles (mi)

1 liter (L) = 1.06 quarts (qt)

236 milliliters (mL) = 1 cup (c)

1 kilogram (kg) = 2.2 pounds (lb)

28.3 grams (g) = 1 ounce (oz)

C = 5/9 x (F 32)Analyzing Biological DataWhat methods of recording data are utilized in science?

How can these tools help biologists analyze data quickly?MicroscopesMicroscopes are devices that produce magnified images of structures that are too small to see with the unaided eye

Types:Light microscopes: produce magnified images by focusing visible light raysElectron microscopes: produce magnified images by focusing beams of electronsLight MicroscopesLight microscopes can produce clear images of objects at a magnification of about 1000X

Compound light microscopes: allow light to pass through the specimen and use two lenses to form an image

Used to observe dead organisms and cells while they are still alive.Electron MicroscopesElectron microscopes are used for objects smaller than 0.2 micrometers (1/50 the diameter of a typical cell)

Electron microscopes can produce images almost 1000X more detailed than light microscopes

Types: Transmission electron microscopes (TEMs): shine a beam of electrons through a thin specimen; give great detail inside the cellScanning electron microscopes (SEMs): scan a narrow beam of electrons back and forth across the surface of a specimen; produce a realistic, 3D image of the surface of objectsLaboratory TechniquesCell cultures: cell is placed into a nutrient solution to replicate from a single original cell

When would we use cell cultures?

Cell fractionation: separate cell partsDisrupt membrane and release partsAdd liquid and transfer into centrifugeMost dense parts of cell are now in the bottom and a biologist can remove the specific part based on density

Metric Measurement LabUsing the knowledge we learned today, complete the worksheet using lab materials supplied at your table.

Who has bigger hands: practice with the scientific method