CVA Biology I - B10vrv1011
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CVA Biology I - B10vrv1011

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Copyright - Adapted from Pearson

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CVA Biology I - B10vrv1011 CVA Biology I - B10vrv1011 Presentation Transcript

  • Lesson OverviewLesson Overview What Is Science?What Is Science?Lesson OverviewLesson Overview1.1 What Is Science?1.1 What Is Science?
  • Lesson OverviewLesson Overview What Is Science?What Is Science?THINK ABOUT ITWhere did plants and animals come from? How did I come to be?Humans have tried to answer these questions in different ways. Someways of explaining the world have stayed the same over time. Science,however, is always changing.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?What Science Is and Is NotWhat are the goals of science?
  • Lesson OverviewLesson Overview What Is Science?What Is Science?What Science Is and Is NotWhat are the goals of science?One goal of science is to provide natural explanations for events in thenatural world. Science also aims to use those explanations to understandpatterns in nature and to make useful predictions about natural events.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?What Science Is and Is NotBiology is not just a collection of never-changing facts or unchangingbeliefs about the world.Some scientific “facts” will change soon—if they haven’t changed already –and scientific ideas are open to testing, discussion, and revision.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Science as a Way of KnowingScience is an organized way of gathering and analyzing evidence aboutthe natural world.For example, researchers can use science to answer questions abouthow whales communicate, how far they travel, and how they areaffected by environmental changes.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Science as a Way of KnowingScience deals only with the natural world.Scientists collect and organize information in an orderly way, lookingfor patterns and connections among events.Scientists propose explanations that are based on evidence, notbelief. Then they test those explanations with more evidence.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?The Goals of ScienceThe physical universe is a system composed of parts and processesthat interact. All objects in the universe, and all interactions amongthose objects, are governed by universal natural laws.One goal of science is to provide natural explanations for events in thenatural world.Science also aims to use those explanations to understand patterns innature and to make useful predictions about natural events.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Science, Change, and UncertaintyDespite all of our scientific knowledge, much of nature remains amystery. Almost every major scientific discovery raises more questionsthan it answers. This constant change shows that science continues toadvance.Learning about science means understanding what we know and whatwe don’t know. Science rarely “proves” anything in absolute terms.Scientists aim for the best understanding of the natural world thatcurrent methods can reveal.Science has allowed us to build enough understanding to make usefulpredictions about the natural world.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Scientific Methodology:The Heart of ScienceWhat procedures are at the core of scientific methodology?
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Scientific Methodology:The Heart of ScienceWhat procedures are at the core of scientific methodology?Scientific methodology involves observing and asking questions, makinginferences and forming hypotheses, conducting controlled experiments,collecting and analyzing data, and drawing conclusions.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Observing and Asking QuestionsScientific investigations begin with observation, the act of noticing anddescribing events or processes in a careful, orderly way.For example, researchers observed that marsh grass grows taller insome places than others. This observation led to a question: Why domarsh grasses grow to different heights in different places?
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Inferring and Forming a HypothesisAfter posing questions, scientists use further observations to makeinferences, or logical interpretations based on what is already known.Inference can lead to a hypothesis, or a scientific explanation for a setof observations that can be tested in ways that support or reject it.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Inferring and Forming a HypothesisFor example, researchers inferred that something limits grass growthin some places. Based on their knowledge of salt marshes, theyhypothesized that marsh grass growth is limited by available nitrogen.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Designing Controlled ExperimentsTesting a scientific hypothesis often involves designing an experimentthat keeps track of various factors that can change, or variables.Examples of variables include temperature, light, time, and availability ofnutrients.Whenever possible, a hypothesis should be tested by an experiment inwhich only one variable is changed. All other variables should be keptunchanged, or controlled. This type of experiment is called a controlledexperiment.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Controlling VariablesIt is important to control variables because if several variables arechanged in the experiment, researchers can’t easily tell which variable isresponsible for any results they observe.The variable that is deliberately changed is called the independentvariable (also called the manipulated variable).The variable that is observed and that changes in response to theindependent variable is called the dependent variable (also called theresponding variable).
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Control and Experimental GroupsTypically, an experiment is divided into control and experimental groups.A control group is exposed to the same conditions as the experimentalgroup except for one independent variable.Scientists set up several sets of control and experimental groups to tryto reproduce or replicate their observations.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Designing Controlled ExperimentsFor example, the researchers selected similar plots of marsh grass. Allplots had similar plant density, soil type, input of freshwater, and heightabove average tide level. The plots were divided into control andexperimental groups.The researchers added nitrogen fertilizer (the independent variable) tothe experimental plots. They then observed the growth of marsh grass(the dependent variable) in both experimental and control plots.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Collecting and Analyzing DataScientists record experimental observations, gathering informationcalled data. There are two main types of data: quantitative data andqualitative data.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Collecting and Analyzing DataQuantitative data are numbers obtained by counting or measuring. Inthe marsh grass experiment, it could include the number of plants perplot, plant sizes, and growth rates.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Collecting and Analyzing DataQualitative data are descriptive and involve characteristics that cannotusually be counted. In the marsh grass experiment, it might includenotes about foreign objects in the plots, or whether the grass wasgrowing upright or sideways.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Research ToolsScientists choose appropriate tools for collecting and analyzing data.Tools include simple devices such as metersticks, sophisticatedequipment such as machines that measure nitrogen content, and chartsand graphs that help scientists organize their data.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Research ToolsThis graph shows how grass height changed over time.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Research ToolsIn the past, data were recorded by hand. Today, researchers typicallyenter data into computers, which make organizing and analyzing dataeasier.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Sources of ErrorResearchers must be careful to avoid errors in data collection andanalysis. Tools used to measure the size and weight of marsh grasses,for example, have limited accuracy.Data analysis and sample size must be chosen carefully. The larger thesample size, the more reliably researchers can analyze variation andevaluate differences between experimental and control groups.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Drawing ConclusionsScientists use experimental data as evidence to support, refute, orrevise the hypothesis being tested, and to draw a valid conclusion.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Analysis showed that marsh grasses grew taller than controls by addingnitrogen.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?Drawing ConclusionsNew data may indicate that theresearchers have the right generalidea but are wrong about a fewparticulars. In that case, the originalhypothesis is reevaluated andrevised; new predictions are made,and new experiments are designed.Hypotheses may have to be revisedand experiments redone severaltimes before a final hypothesis issupported and conclusions can bedrawn.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?When Experiments Are Not PossibleIt is not always possible to test a hypothesis with an experiment. Insome of these cases, researchers devise hypotheses that can be testedby observations.Animal behavior researchers, for example, might want to learn howanimal groups interact in the wild by making field observations thatdisturb the animals as little as possible. Researchers analyze data fromthese observations and devise hypotheses that can be tested indifferent ways.
  • Lesson OverviewLesson Overview What Is Science?What Is Science?When Experiments Are Not PossibleSometimes, ethics prevents certain types of experiments—especially onhuman subjects.For example, medical researchers who suspect that a chemical causescancer, for example, would search for volunteers who have alreadybeen exposed to the chemical and compare them to people who havenot been exposed to the chemical.The researchers still try to control as many variables as possible, andmight exclude volunteers who have serious health problems or knowngenetic conditions.Medical researchers always try to study large groups of subjects so thatindividual genetic differences do not produce misleading results.