21-1 What is the goal of Science? Investigate and understand natureExplain events in natureUse those explanations to make useful predictions
3What is Science?An organized way of using evidence to learn about the natural worldBody of knowledge that scientists have built up after years of using this process
4The Scientific Method Stating Problem/Observations Hypothesis ExperimentationData collection and analysisConclusionAnswer to problemValidity (restate data)Prove/Disprove hypothesisErrorsImprovements
5Observations *using the senses to gather/collect data Quantitative-observations based on numbers or quantitiesEx.Counting/measuring7 birds, 14 miles, 200 peopleQualitative-observations based on descriptionEx. Color/textureblue neck, large teeth, soft cushion
6Objective vs. Subjective Observations Objective-without a predetermined point of view, unbiasedSubjective-with a predetermined point of view, biased (dangerous-Jews inferior to Germans)
7HypothesisA possible answer to a scientific question or an explanation for a series of observations.Ex. Use hypothesis to discover how infected disease was contracted:-spread by human contact?-spread through insect bites?-spread through contaminated air/water/food?**All of these are then tested to find the correct explanation.
8Experimentation Controlled steps used to test the hypothesis Controlled Experiment-only 1 variable is changed and all others are kept unchanged, or controlled.
9VariablesIndependent/Manipulated: the one that is deliberately changed/tested (only 1); on X axis.Dependent/Responding: the one that is measured and changes in RESPONSE to the independent variable; on Y axis.Controls: those that remain constant/unchanged
10Data Collection and Analysis Clear, precise, and objectiveDisplayed in table/graphUnderstanding and making sense of observationsWhat does your data tell you about the experiment?
11Conclusion Analyzing data brings you to a final decision/conclusion Evidence found supports or refutes hypothesiswill test correct or wrong
12Role of ExperimentsProcedures used to study a phenomenon under known conditionsAllows you to predict what will happen if a hypothesis is not wrongCan never prove a hypothesis 100% correct
13Experimental Design Control group Experimental group A standard for comparisonIdentical to experimental group except no independent variable presentExperimental groupIndependent variable present and being tested
14CONTROL GROUP EXPERIMENTAL GROUP Draw samples from some aspect of natureCONTROL GROUPThe variable beingtested is absentEXPERIMENTAL GROUPThe variable beingtested is presentCompile resultsCompile resultsCompare and analyze the test resultsReport on experimental design, test results, and conclusions drawn from results
151-2 Spontaneous Generation Belief that living things arose from non-living thingsExamples:Maggots come from meatMice from wheatBeetles from cow dung
17Francesco Redi and 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 Variables: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.
18What is Redi’s Conclusion? Spontaneous generation does not occur.
19The Return of Spontaneous Generation Anton van Leeuwenhoek – uses a microscope to find tiny organisms swimming in pond water. “animalcules”John Needham (mid 1700’s) performs an experiment that refutes RediLazzaro Spallanzani – improves Needham’s experiment
20What are the controlled variables? What are the independent variables? Figure 1-10 Spallanzani’s ExperimentSection 1-2What are the controlled variables?What are the independent variables?Gravy is boiled.Flask isopen.Gravy is teemingwith microorganisms.Flask issealed.Gravy is free ofmicroorganisms.Gravy is boiled.What are the dependent variables?
22The debate continuesIn the 1800’s some believe the air contained a “life force” perpetuating the belief of spontaneous generation.Louis Pasteur –1864, his experiment finally disproved spontaneous generation
23Figure 1-11 Pasteur’s Experiment Section 1-2Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
24Figure 1-11 Pasteur’s Experiment Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
25Figure 1-11 Pasteur’s Experiment Broth is boiled.Broth is free ofmicroorganismsfor a year.Curved neckis removed.Broth isteeming with microorganisms.
26Pasteur’s Conclusions All living things must come from other living things.Opening the jar (Redi) exposes the contents to come in contact with organisms in the air, just as breaking neck of flask(pg.13)What improvement did Pasteur make to Redi’s experiment?
27What is a Theory?A well tested explanation that unites many observations (evidence builds up to make hypothesis very well supported)Can be proven wrong when new data arises to refute it.May be revised or replaced by a more useful explanation.
28List 5 things that all living things do: 1-3 Studying LifeWhat do all living things have in common?List 5 things that all living things do:
35Characteristics of Living Things: Made of units called cellsReproduceBased on universal genetic codeGrow and developObtain/use materials and energyRespond to environmentMaintain stable internal environmentChange over time
37A CellCollection of living matter enclosed by barrier separating the cell from its surroundings.Smallest units of an organism that can be considered alive.Small size, but highly organized and complex.
38Asexual Reproduction New organism has a single parent (ex Asexual Reproduction New organism has a single parent (ex. Budding hydra)
39Sexual Reproduction 2 cells from different parents unite to produce new organism (ex. Sperm and egg)
40Universal Genetic Code Universal Genetic Code **Everything living is based on this the molecule of inheritance
42Required for Life… Metabolism -chemical reactions an organism uses to build up and break down materials-how cells acquire and use energy to grow and survive(ex. Digestion, making proteins)Homeostasis-keeping the internal conditions of an organism stable(ex. Body temperature, breathing, heart rate)
43Nothing Lives Without Energy Energy = Capacity to do work
44HomeostasisMaintenance of internal environment within range suitable for cell activitiesEx. pancreas maintains level of sugar in blood by secreting hormones
45Sensing and Responding Organisms sense changes in their environment and make responses to themReceptors detect specific forms of energyThe form of energy detected by a receptor is a stimulus
46Evolution - as a group all living things change over time
47Evolution Genetically based change in a line of descent over time Population changes, not individuals
48Figure 1-21 Levels of Organization BiosphereThe part of Earththat contains allecosystemsBiosphereCommunity andits nonlivingsurroundingsEcosystemHawk, snake, bison, prairie dog, grass, stream, rocks, airCommunityPopulations thatlive together in adefined areaHawk, snake, bison, prairie dog, grassGroup oforganisms of onetype that live inthe same areaPopulationBison herd
49Figure 1-21 Levels of Organization continued Individual livingthingBisonOrganismGroups ofCellsTissues, organs,and organ systemsNervous systemNervous tissueBrainCellsSmallest functionalunit of lifeNerve cellGroups of atoms;smallest unit ofmost chemicalcompoundsDNAWaterMolecules
50What are the different levels of organization in Biology What are the different levels of organization in Biology? Smallest to Largest
51AtomSmallest unit of an a element that retains the properties of that element
64Metric System-SI-International System of Units To collect data and perform experimentsDecimal system of units scaled on multiples of 10Measures: length, mass, volume, and temperature
65How can a graph help biologists to organize this data?
66Microscopes-produce magnified images of structures too small for naked eye Light Microscope-produce magnified images by focusing visible light rays.Up to 1000 times.Live and dead organismsFig (compound light microscope)Electron Microscopes- produce magnified images by focusing beams of electrons.Form images 1000 times more detailed than light microscope.Fig. 1-26Only dead organisms.Have no color. Why?