Transcript 1.1 Defining Life

Chapter 1: pp. 1 - 24
A View of Life
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Warm-Up Question
What is the definition of the word life?
1.1 Defining Life
Living organisms can be Microscopic:
Bacteria
Paramecium
Living organisms can be Macroscopic (Multi-cellular):
Snow goose
Humans
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Bacteria
Paramecium
Morel
Sunflower
Snow goose
(Bacteria): © Dr. Dennis Kunkel/Phototake; (Paramecium): © M. Abbey/Visuals Unlimited; (Morel): © Royalty-Free Corbis;
(Sunflower): © Photodisc Green/Getty Images; (Snow goose): © Charles Bush Photography
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1.1 Defining Life

Living 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 cells
 Cells are the smallest units to perform all vital
physiological functions

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Levels of Biological Organization
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Biosphere
Regions of the Earth’s crust,
waters, and atmosphere
inhabited by living things
Ecosystem
A community plus
the physical environment
Community
Interacting populations in a
particular area
Population
Organisms of the same
species in a particular area
Organism
An individual; complex
individuals contain organ systems
Organ System
Composed of several organs
working together
Organ
Composed of tissues functioning
together for a specific task
Tissue
A group of cells with a common
structure and function
Cell
The structural and functional
unit of all living things
Molecule
Union of two or more atoms of
the same or different elements
Atom
Smallest unit of an element composed of
electrons, protons, and neutrons
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
nutrients



Metabolism is all the chemical reactions that
occur in a cell or in an organism.
The sun is the ultimate source of energy
Homeostasis - Maintenance of internal conditions
within certain boundaries
 Temp, moisture, acidity
 Monitored by internal systems
 Feedback mechanisms
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energy
input,
from sun
Producers
(plants, and other selffeeding organisms)
Nutrient
Cycling
Consumers
Animals, most fungi, many
protists, many bacteria
energy output (mainly metabolic heat)
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
common
ancestor
(first cells)
ARCHAEA
Protists
Photosynthetic
protist
Plants
cell with nucleus
EUKARYA
Fungi
Heterotrophic
Protist
Animals
common ancestor
Past
Present
Time
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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

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
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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
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B. Common Descent with Modification

Natural Selection – a process by which the
environment selects traits to be passed on to the
next generation

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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
Organization of the Biosphere

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
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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heat
Terrestrial Ecosystems: A Grassland
solar
energy
heat
heat
heat
heat
Chemical cycling
heat
WASTE MATERIAL, DEATH,
AND DECOMPOSITION
Energy flow
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Human Populations

Humans modify ecosystems & upset natural
nutrient cycles

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Ex: tropical rainforest, coral reefs
However, humans depend upon healthy ecosystems
for

Food

Medicines

Raw materials

Other ecosystem processes
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Biodiversity


Biodiversity – 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
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Observation
New observations
are made, and previous
data are studied.
Hypothesis
Input from various
sources is used to formulate
a testable statement.
Experiment/Observations
Conclusion
The hypothesis is
tested by experiment
or further observations.
The results are analyzed,
and the hypothesis is
supported or rejected.
Scientific Theory
Many experiments and
observations support a
theory.
Courtesy Leica Microsystems Inc.
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Warm-Up Question
What are the steps of the scientific process?
Explain the purpose of each step.
1.4 The Scientific Method


Scientific method is a standard series of steps
in gaining new knowledge through research.
Begins with observation

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Use of senses to understand a natural event
After making the observation use inductive
reasoning to lead to...
Hypothesis - A tentative explanation for what
was observed
Can be tested
 Past 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
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If not, hypothesis is unsupportable
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Experimental Design

How the scientist will conduct the experiment

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Ensures they are testing what they want
Control group
Experimental Group
Could use a model
Controlled Experiments

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Experimental (Independent) variable
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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
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A couple of biologist had twins, one they
called John and the other - control.
Results

Results or Data

Observable, objective
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Mathematical Data – graph/table

Statistical Data - probability that random variation
could have caused the results
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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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Conclusion


Analyze data to reach conclusion as to whether
the hypothesis is supported or not
Conclusions are what the scientist thinks
caused the results

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
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
resident
male
b. Normal mountain
bluebird nesting
behavior
male
bluebird
model
Approaches per Minute
2.0
c. Resident male
attacking a male
model near nest
Approaches to
male model
1.5
1.0
0.5
Approaches to
female mate
nest 1
nest 2
0
nest
construction
first egg
laid
hatching
of eggs
Stage of Nesting Cycle
female
mate
d. Observation of two experimental nests provided data
for graph.
© Erica S. Leeds
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