21-1 What Is Science? What is the goal of science? So what is science? To understand the world around us.So what is science?An organized way of using evidence to learn about the natural world.
3Thinking Like a Scientist Scientists record observations.Information gathered using the senses. Ex: there is a person standing in the front of the room.DataQualitative data – descriptive ; ex: rough or smoothQuantitative data – numerical; counted or measured ; ex: 12 apples or 52.5 grams.Most experiments contain both types of data.An inference may follow an observation.A logical interpretation based on prior knowledge or experience.Ex: the person is a teacher.
4Observation and Inference Section 1-1Statement Observation InferenceObject A is round and orange.XObject A is a basketball.Object A is a basketball.Object B is a table-tennisball.Object C is a soccer ball.Object C is round and black and white.Object C is larger than Object B.Object B is smooth.Object B is a table-tennis ball.Each object is used in a different sport.
5Note the differencesIn laboratory exercises, record observations NOT inferencesInferences may be used when writing the conclusion to your lab.Let’s test your observation skills…You’ll need a piece of paper and a writing utensil
7Answer these questions Are there cars parked on the sides of the road?What color is the pickup truck driving in the road?Any minivans around?What does the green sign say?Were there any pedestrians on the road?What's the speed limit?
8Question 1Are there cars parked on the sides of the road?
20Observation vs. Inference On the next slide, state whether the statement is an observation or an inference.
211. There is a representation of a face on one side of the coin. 2. The Latin word "Dei" means "God."3. The coin was made by deeply religious people.4. The date 1722 is printed on one side of the coin.5. The coin was made in 1722.6. The face on the coin is a representation of the nation's president.
23Explaining and Interpreting Evidence What is a hypothesis?A proposed explanation for an observed set of facts.Must be testable by performing controlled experiments and collecting dataSome hypotheses may be supported, and others may not be supported.
24Science as a Way of Knowing Science is an ongoing process – it continually changes.Good scientists are skeptics; they question new as well as existing ideas.
251-2 How Scientists WorkAbout 2000 years ago a Roman poet wrote these directions for producing bees:Kill a bull during the first thaw of winter.Build a shed.Place the dead bull on branches and herbs inside the shed.Wait for summer. The decaying body of the bull will produce bees.
26Spontaneous Generation Aristotle proposed 2300 years ago that a “vital force” was present in the air that caused living things to arise from nonliving things.This was called spontaneous generation.In the 1600s, scientists began to question this theory.To test this theory, scientists used the scientific method.
27Flowchart Designing an Experiment State the Problem Analyze Results Section 1-2Designing an ExperimentState the ProblemAnalyze ResultsForm a HypothesisDraw a ConclusionSet Up a Controlled ExperimentPublish ResultsRecord Results
28A Different Hypothesis In the 1600s, people believed rotting meat produced maggots spontaneously.In 1668, Francesco Redi proposed that flies were landing on the meat and laying eggs, which hatched into maggots.He conducted a controlled experiment to test his hypothesis.In a controlled experiment only one variable is tested at a time.
29Redi’s Experiment on Spontaneous Generation Section 1-2OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.HYPOTHESIS: Flies produce maggots.PROCEDUREUncovered jarsCovered jarsControlled Variables:jars, type of meat,location, temperature,timeSeveraldays passIndependent Variable:gauze covering thatkeeps flies away frommeatDependent Variable:whether maggotsappearMaggots appearNo maggots appearCONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
30BiogenesisRedi concluded that living things could only come from other living things.
31Repeating Investigations In the 1700s John Needham, an English scientist, conducted an experiment to test Redi’s idea (skeptic).He said animalcules could arise from gravy, contradicting Redi’s work.He boiled gravy, sealed the flask, and days later microorganisms appeared in the flask thus “supporting” the theory of spontaneous generation.
32Repeating Investigations An Italian scholar, Lazzaro Spallanzani, didn’t believe Needham’s results (skeptic).He said Needham didn’t boil the gravy long enough, so he repeated his experiment with modifications…
33Figure 1-10 Spallanzani’s Experiment Section 1-2Gravy is boiled.Flask isopen.Gravy is teemingwith microorganisms.Flask issealed.Gravy is free ofmicroorganisms.Gravy is boiled.
34Biogenesis again…Spallanzani concluded that nonliving gravy did not produce living things. The microorganisms came from the air.
35Repeating Investigations By the 1800s, some scientists still supported the theory of spontaneous generation.They felt sealing the flask cut off the “vital life force” in the air.In 1864, Louis Pasteur settled the debate.He designed a flask that could keep airborne microbes out without being sealed.
36Figure 1-11 Pasteur’s Experiment Section 1-2Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
37Figure 1-11 Pasteur’s Experiment Section 1-2Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
38Figure 1-11 Pasteur’s Experiment Section 1-2Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
39Figure 1-11 Pasteur’s Experiment Section 1-2Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
40Pasteur’s WorkLouis Pasteur’s work revolutionized the food and wine industry.The process of heating foods until microorganisms are killed before packaging is called “Pasteurization”.
41Alternative Investigations Controlled experiments are not always possible.Field studies - animalsMedical research – clinical trialsEnvironmental researchScientific methodology is still used:Large study groupsControlled variables
42TheoriesThe theory of biogenesis developed from many experiments that tested the hypothesis that new organisms come from existing organisms.When a hypothesis becomes very well supported it is considered a theory.A theory is defined as a well tested explanation that unifies a broad range of observations.Can theories change?Can a theory be proven true?
431-3 Studying Life Biology – -bios = life-logy = study ofLiving things share certain characteristics.
44Characteristics of Living Things Section 1-3CharacteristicExamplesLiving things are made up of units called cells.Many microorganisms consist of only a single cell. Animals and trees are multicellular.Living things reproduce.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Living things are based on a universal genetic code.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Living things grow and develop.Flies begin life as eggs, then become maggots, and then become adult flies.Living things obtain and use materials and energy.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.Living things respond to their environment.Leaves and stems of plants grow toward light.Living things maintain a stable internal environment.Despite changes in the temperature of the environment, a robin maintains a constant body temperature.Taken as a group, living things change over time.Plants that live in the desert survive because they have become adapted to the conditions of the desert.
45Branches of Biology Zoologists – Botanists – Paleontologists – animalsBotanists –plantsPaleontologists –ancient lifeMicrobiologists –microscopic lifeImmunologists –DiseaseEcologists –Organisms and their environment
46Levels of Organization Living things may be studied on many different levels.The largest and most complex level is the biosphere.The smallest level is the molecule.
47Levels of Organization Section 1-3BiosphereThe part of Earththat contains allecosystemsBiosphereEcosystemCommunity andits nonlivingsurroundingsHawk, snake, bison, prairie dog, grass, stream, rocks, airCommunityPopulations thatlive together in adefined areaHawk, snake, bison, prairie dog, grassPopulationGroup oforganisms of onetype that live inthe same areaBison herd
48Levels of Organization continued Section 1-3OrganismIndividual livingthingBisonTissues, organs,and organ systemsGroups ofCellsNervous tissueBrainNervous systemSmallest functionalunit of lifeCellsNerve cellGroups of atoms;smallest unit ofmost chemicalcompoundsMoleculesWaterDNA
491-4 Tools and Procedures Scientists use a common measurement system: The metric system, or SISome standard units of measurement are:Length –MeterRuler or meter stickVolume –LiterGraduated cylinder or pipetMass –GrambalanceTemperatureCelsiusthermometer
50Analyzing DataData tables are used to stay organized when recording data.Graphs are used to make data easier to interpret and see trends (patterns).
51Making a Graph From A Data Table Section 1-4Making a Graph From A Data TableWater Released and Absorbed by TreeAbsorbedby Roots(g/h)Releasedby Leaves(g/h)20Water released by leavesTime158 AM12Relative Rates (g/h)1010 AM1512 PM41252 PM617Water absorbed by roots4 PM9166 PM14108 AM10 AM12 PM2 PM4 PM6 PM8 PM8 PM103Time
52MicroscopesDevices that produce magnified images of structures that are too small to see with the unaided eye.Three common microscopes are:Light microscopeCan magnify up to 1000XUseful for viewing cellsElectron microscopeCan magnify up to 100,000XUseful for seeing parts of cellsDissecting (stereo) microscopeCan magnify up to 5XUseful for dissections
56Laboratory Techniques Two common techniques for studying cells are cell culture and cell fractionation.Cell cultureCells are grown in sterile dishesEspecially useful for growing stem cellsCell fractionationCells are broken apart in a blenderCell parts are separated in a centrifuge