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A View of Life

Chapter 1: pp. 1 - 24

Warm-Up Question

What is the definition of the word life?

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1.1 Defining Life

Living organisms can be Microscopic:

Bacteria

Paramecium

Living organisms can be Macroscopic (Multi-cellular):

Snow goose

HumansCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(Bacteria): © Dr. Dennis Kunkel/Phototake; (Paramecium): © M. Abbey/Visuals Unlimited; (Morel): © Royalty-Free Corbis; (Sunflower): © Photodisc Green/Getty Images; (Snow goose): © Charles Bush Photography

Bacteria Paramecium Morel Sunflower Snow goose

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1.1 Defining LifeLiving things:

All made of chemical elements

All are organized: atoms → molecules → cells

Cells (Unicellular or Multi-cellular).The basic structural and functional unit of all

living things Cells are produced from preexisting cellsCells are the smallest units to perform all vital

physiological functions

Levels of Biological Organization

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OrganComposed of tissues functioning

together for a specific task

TissueA group of cells with a common

structure and function

CellThe structural and functional

unit of all living things

MoleculeUnion of two or more atoms ofthe same or different elements

AtomSmallest unit of an element composed of

electrons, protons, and neutrons

BiosphereRegions of the Earth’s crust,

waters, and atmosphereinhabited by living things

Ecosystem A community plus

the physical environment

CommunityInteracting populations in a

particular area

PopulationOrganisms of the same

species in a particular area

OrganismAn individual; complex

individuals contain organ systems

Organ SystemComposed of several organs

working together

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A. LT are Organized

Each level of organization builds on the previous

Acquires emergent properties:

Interactions between the parts making up the whole

All emergent properties follow the laws of physics and chemistry

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B. Living Things: Acquire & Process Food

LT maintain organization with energy and nutrientsMetabolism is all the chemical reactions that

occur in a cell or in an organism.The sun is the ultimate source of energyHomeostasis - Maintenance of internal conditions

within certain boundariesTemp, moisture, acidityMonitored by internal systemsFeedback mechanisms

energy input,

from sun

NutrientCycling

Producers(plants, and other self-

feeding organisms)

ConsumersAnimals, most fungi, many

protists, many bacteria

energy output (mainly metabolic heat)

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C. Living Things: Respond to Stimuli

Living things interact with the environment and other LT

Response ensures survival of the organism and it often results movement Vulture can detect and find carcass a mile away and soar toward dinner

Monarch butterfly senses approach of fall and migrates south

Microroganisms can sense light or chemicals

Even leaves of plants follow sun

Activities as a result of Responses are termed behavior

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D. Living Things: Reproduce and Develop Every LT can

reproduce or make another organism like itself

Simply split in two

Union of egg and sperm, followed by many cell divisions

Must reproduce to ensure continued existence and maintain population

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E. Living Things: Adapt to Change

Adaptation

Modifications that make organisms better able to function in a particular environment

These take a long period time

Leads to evolution Population changes over many generations

to better suit their environment

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1.2 Evolution, the Unifying Concept of Biology

Organisms share the same basic characteristics Cells organized in a similar manner

Genes are composed of DNA

Same metabolic reactions to acquire energy

Suggests they are descended from a common ancestor Evolutionary tree

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Evolutionary Tree of Life

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BACTERIA

ARCHAEA

EUKARYA

Protists

commonancestor(first cells)

cell with nucleus

Past

Time

Present

Photosyntheticprotist

HeterotrophicProtist

Plants

Fungi

Animalscommon ancestor

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A. Organizing Diversity

Taxonomy: ID and group organisms according to certain rules

Levels are, from least inclusive to most inclusive:Species, genus, family, order, class, phylum, kingdom,

and domain

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Domains

Bacteria - Microscopic unicellular prokaryotes

Archaea - Bacteria-like unicellular prokaryotes, living in extreme aquatic environments

Eukarya – Eukaryotes (protists, plants, fungi, animals)

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Scientific Names

Binomial nomenclature (two-word names)- used to assign each organism with two part name

Latin-based to avoid confusion First word = genus of organism e.g. Homo Second word = specific epithet or genus of a

species within the genus e.g. Sapience Always italicized as a Genus species (Homo

sapiens) Genus may be abbreviated e.g. Escherichia Coli as

E. Coli

B. Common Descent with Modification

Natural Selection – a process by which the environment selects traits to be passed on to the next generation

Biotic and abiotic influence Mutations fuel by the intro of variations All individuals can reproduce but not

all do with same success rate

Natural selection

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Organization of the Biosphere

Biosphere – air, land, and water where organisms exist

Population - Members of a species within an area

Community - A local collection of interacting populations making Ecosystems

Food webs

Chemical cycling and energy flow

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Terrestrial Ecosystems: A GrasslandCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

WASTE MATERIAL, DEATH,AND DECOMPOSITION

heat

heat

heat

heat

heat

solarenergy

Chemical cycling

Energy flow

heat

heat

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Human Populations

Humans modify ecosystems & upset natural nutrient cycles Ex: tropical rainforest, coral reefs

However, humans depend upon healthy ecosystems for Food

Medicines

Raw materials

Other ecosystem processes

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BiodiversityBiodiversity – total # & relative

abundance of species

The variability of their genes

The ecosystems in which they live

Extinction is – the death of a species

Estimates of 400 species/day lost worldwide

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The Scientific Method: A Flow Diagram

Observation

New observationsare made, and previous

data are studied.

Hypothesis

Input from varioussources is used to formulate

a testable statement.

Conclusion

The results are analyzed,and the hypothesis issupported or rejected.

Scientific Theory

Many experiments andobservations support a

theory.

Experiment/Observations

The hypothesis istested by experiment

or further observations.

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Courtesy Leica Microsystems Inc.

Warm-Up Question

What are the steps of the scientific process? Explain the purpose of each step.

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1.4 The Scientific MethodScientific method is a standard series of steps

in gaining new knowledge through research.Begins with observation

Use of senses to understand a natural eventAfter making the observation use inductive

reasoning to lead to...Hypothesis - A tentative explanation for what

was observed

Can be testedPast experiences can influence

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The Scientific Method: Experimentation

Experimentation Use deductive reasoning to determine how to test

If, then logic

Predicts how groups should differ if hypothesis is valid If prediction happens, hypothesis is unchallenged

If not, hypothesis is unsupportable

Experimental Design

How the scientist will conduct the experiment Ensures they are testing what they want Control group Experimental Group Could use a model

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Controlled Experiments

Experimental (Independent) variable

Applied one way to experimental group

Applied a different way to control group

Response (dependent) variable

Variable that is measured to generate data

Expected to yield different results in control versus experimental group

A couple of biologist had twins, one they called John and the other - control.

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Results

Results or Data

Observable, objective

Mathematical Data – graph/table

Statistical Data - probability that random variation could have caused the results

Low probability (less than 5%) is good

Higher probabilities make it difficult to dismiss random chance as the sole cause of the results

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ConclusionAnalyze data to reach conclusion as to

whether the hypothesis is supported or not

Conclusions are what the scientist thinks caused the results

Could lead to the hypothesis for another experiment

Report findings in scientific journals to be Peer reviewed

Others then attempt to duplicate or dismiss

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Scientific Theory

Scientific Theory:

Joins together two or more related hypotheses

Supported by broad range of observations, experiments, and data

Ex: cell, homeostasis, gene, ecosystem, evolution

Scientific Principle / Law:

Widely accepted set of theories

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A Field Study

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a. Scientist making observations

b. Normal mountain bluebird nesting behavior

c. Resident male attacking a male model near nest

residentmale

femalemate

malebluebirdmodel

d. Observation of two experimental nests provided data for graph.

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nestconstruction

first egglaid

hatchingof eggs

Stage of Nesting Cycle

Approaches tomale model

Approaches tofemale mate

nest 2nest 1

© Erica S. Leeds