Invitation to BiologyChapter 11.1 Impacts/Issues:The Secret Life of Earth

Biology The systematic study of life

We have encountered only a fraction of the organisms that live on EarthScientists constantly discover new speciesExtinction rates are accelerating

Video: Lost worlds and other wondersExploring New GuineaA rare golden-mantled tree kangaroo

1.2 Lifes Levels of Organization

The building blocks (atoms) that make up all living things are the same ones that make up all nonliving things

The unique properties of life emerge as certain kinds of molecules become organized into cellsLifes Levels of OrganizationAtomFundamental building block of all matter

MoleculeAn association of two or more atoms

CellSmallest unit of life

OrganismAn individual; consists of one or more cellsLifes Levels of OrganizationPopulationGroup of individuals of a species in a given area

CommunityAll populations of all species in a given area

EcosystemA community interacting with its environment

BiosphereAll regions of Earth that hold lifeNature and Life

NatureEverything in the universe, except what humans have manufactured

Emergent propertyA characteristic of a system that does not appear in any of a systems component partsLevels of Organization in Nature

Animation: Lifes levels of organizationActive Figure: Levels of organization1.3 Overview of Lifes Unity

All living things have similar characteristicsRequire energy and nutrientsSense and respond to changeReproduce with the help of DNAEnergy Sustains Lifes Organization

One-way flow of energy through the biosphere and cycling of nutrients among organisms sustain lifes organization

EnergyThe capacity to do work

NutrientSubstance that is necessary for survival, but that an organism cant make for itselfOrganisms and Energy Sources

ProducersOrganisms that make their own food using energy and simple raw materials from the environmentExample: plants

ConsumersOrganisms that get energy and carbon by feeding on tissues, wastes, or remains of other organismsExample: animals

Energy Flow and Material Cycling

Animation: One-way energy flow and materials cyclingOrganisms Sense and Respond to ChangeOrganisms sense and respond to change to keep conditions in their internal environment within a range that favors cell survival (homeostasis)

HomeostasisSet of processes by which an organism keeps its internal conditions within tolerable ranges

ReceptorMolecule or structure that responds to a stimulusResponse to StimuliOrganisms Grow, Develop and Reproduce

Organisms grow, develop, and reproduce based on information encoded in DNA, which they inherit from their parents

GrowthIncrease in size, volume, and number of cells in multicelled species

DevelopmentMultistep process by which the first cell of a new individual becomes a multicelled adultOrganisms Grow, Develop and Reproduce

ReproductionProcess by which parents produce offspring

InheritanceTransmission of DNA from parents to offspring

DNA (Deoxyribonucleic acid)Molecule that carries hereditary information about traits1.4 Introduction to Lifes DiversityThe millions of species on Earth vary greatly in details of body form and function

Each species is given a unique two-part name that includes genus and species names

SpeciesA type of organism

GenusGroup of species that share a unique set of traitsClassification Systems

Classification systems group species according to traits and organize information about species

One system sorts all organisms into one of three domains: Bacteria, Archaea, and Eukarya

The eukaryotes include plants, protists, fungi and animalsLifes Diversity: Three-Domain Classification System

Animation: Lifes diversityProkaryotes

ProkaryotesSingle celled organisms in which DNA is not contained in a nucleus

BacteriumA member of the prokaryotic domain Bacteria

ArchaeansA member of the prokaryotic domain ArchaeaEukaryotes

EukaryotesOrganisms whose cells typically have a nucleus

FungusEukaryotic consumer that obtains nutrients by digestion and absorption outside the body

ProtistsEukaryotes that are not plants, animals, or fungiEukaryotes

PlantTypically a multicelled, photosynthetic producer

AnimalMulticelled consumer that develops through a series of embryonic stages and moves about during all or part of the life cycle

Animation: Three domains1.5 The Nature of Scientific Inquiry

Critical thinkingMental process of judging the quality of information before deciding whether or not to accept itThe Scope and Limits of Science

Science is a way of looking at the natural world which helps us to communicate our experiences without bias by focusing only on testable ideas about observable phenomenaScience does not address the supernatural

ScienceThe systemic study of nature1.6 How Science Works

Researchers make and test potentially falsifiable predictions about how the natural world works

Generally, scientific inquiry involves forming a hypothesis (testable assumption) about an observation then making and testing predictions based on the hypothesis

A hypothesis that is not consistent with the results of scientific tests is modified or discarded

Common Research Practices

1. Observe some aspect of nature

2. Frame a question about your observation

3. Propose a hypothesis (a testable explanation of the observation)Common Research Practices

4. Make a prediction a statement based on a hypothesis, about some condition that should exist if the hypothesis is not wrong

5. Test the accuracy of the prediction by experiments or gathering information (tests may be performed on a model) Common Research Practices

6. Assess the results of the tests (data) to see if they support or disprove the hypothesis

7. Conclusions: Report all steps of your work and conclusions to the scientific communityMaking Observations: A Field StudyA Scientific Theory

Scientific theoryA hypothesis that has not been disproven after many years of rigorous testingUseful for making predictions about other phenomena

Laws of Nature

Law of natureGeneralization that describes a consistent and universal natural phenomenon for which we do not yet have a complete scientific informationExample: gravity

Examples of Scientific TheoriesAnimation: An example of the scientific method1.7 The Power of Experiments

Natural processes are often influenced by many interacting variables

VariableA characteristic or event that differs among individuals

The Power of Experiments

Experiments simplify interpretations of complex biological systems by focusing on the effect of one variable at a time

ExperimentA test to support or falsify a prediction

Experimental and Control Groups

Experimental groupA group of objects or individuals that display or are exposed to a variable under investigation

Control groupA group of objects or individuals that is identical to an experimental group except for one variable

Potato Chips and Stomachaches

Example: Butterflies and BirdsQuestionWhy does a peacock butterfly flick its wings?

Two hypothesesExposing wing spots scares off predatorsWing sounds scare off predators

Two predictionsIndividuals without spots are eaten more oftenIndividuals without sounds are eaten more oftenPeacock Butterfly DefensesExperiments and Results

Four groups of butterflies were exposed to predators (birds)Butterflies without spotsButterflies without soundsButterflies without spots or soundsControl group

Test results support both original hypotheses

Results: Peacock Butterfly ExperimentSampling Error

Biology researchers experiment on subsets of a group, which may result in sampling error

Sampling errorDifference between results derived from testing an entire group of events or individuals, and results derived from testing a subset of the groupSampling Error

Probability

Researchers try to design experiments carefully in order to minimize sampling error

Statistically significantRefers to a result that is statistically unlikely to have occurred by chanceAnimation: Sampling error1.8 Impacts/Issues RevisitedBiologists constantly discover new speciesMouse lemur (Microcebus lehilahytsara), discovered in Madagascar in 2005

Digging Into Data:Peacock Butterfly Predator Defenses