Study of
Characteristics
of Life
copyright cmassengale
Edited by pdunning EHS
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What is Biology?
Biology is the study
of all living things
Living things are
called organisms
Organisms include
bacteria, protists,
fungi, plants, &
animals
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All Living Things Share
Common Characteristics
1. Basic Unit is the Cell
2. They Reproduce
3. All Based On
Universal Genetic
Code (DNA)
4. Grow & Develop
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Common Characteristics
5. Obtain & Use Materials &
Energy
6. Respond To Their Environment
7. Maintain A Stable Internal
Environment
8. AS A GROUP, Living Things
Evolve, That Is They Change
Over Time
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Characteristics of Organisms
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All Organisms are
made of Cells
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Cell Structure and Function
Cell basic unit of life
All organisms are made
of and develop from
cells
Some composed of only
a single cell
(unicellular) which is
usually identical to
parent
Facts About Cells
Cells are the smallest living unit
of an organism
All cells contain cytoplasm
All cells are surrounded by a cell
membrane that controls what
enters & leaves the cell
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More Cell Facts
Cells are complex &
highly organized
Cells have parts called
organelles that do
different jobs
e.g. Chloroplasts in
plants make sugars
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More Cell Facts
The simplest cells are
called Prokaryotes
These cells DO NOT
have a nucleus or
membrane-bound
organelles
Bacteria are examples
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More Cell Facts
More complex cells are
called Eukaryotes
These cells DO have a
nucleus and membranebound organelles
Plants, animals,
protists, & fungi are
examples
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Organisms are Grouped by
their Number of Cells
Unicellular Organisms
– Living Organism Made Up Of One
Cell
Multicellular Organisms
– Living Organism Made Up Of
Many, Specialized Cells
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Cells
All living things are
composed of cells
In multicellular
organisms, many are
specialized to perform
specific functions
Cells are always very
small
The size of multi-celled
organisms depends on
the number of cells
NOT their size
Copyright Cmassengale
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Living things reproduce
Copyright Cmassengale
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Organisms Reproduce to
Pass on their Genetic
Traits
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Reproduction
 All species have the ability to reproduce
Not essential to survival of individual but
is essential for continuation of a species
Copyright Cmassengale
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Two Types of Reproduction
Sexual
Reproduction
Involves 2 parents
Egg fertilized by
sperm to make a
ZYGOTE
Offspring
DIFFERENT from
parents
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Two Types of Reproduction
Asexual
Reproduction
Involves a single
organism or cell
Cell divides
Offspring
IDENTICAL to
parent
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Cells Have a Genetic Code
copyright cmassengale
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Genetic Code
DNA (deoxyribose nucleic
acid) carries the genetic
code for all organisms
All organisms contain DNA
DNA codes for the
proteins that make up cells
& do all the work
necessary for life
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Organisms Grow & Develop
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Growth & Development
Organisms grow by
producing MORE
CELLS & by cell
ENLARGEMENT
Organisms develop as
they mature into an
adult organism
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Growth
Grow occurs as the result of cell
division and cell enlargement
Cell division is the formation of
two cells from a preexisting cell
New cells enlarge as they mature
When a cell grows to a size
where its surface area isn’t big
enough for its volume, the cell
divides
Copyright Cmassengale
23
Cells Require Food & Energy
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Food Requirements
Autotrophs can make
their own food
Photoautotrophs use
sunlight to make food
(photosynthesis)
Chemoautotrophs use
chemicals such as iron
& sulfur as their
energy
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Food Requirements
Heterotrophs can NOT make their
own food
They must consume other
organisms
Herbivores eat plants
Carnivores eat meat
Omnivores eat plants & animals
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All organisms need substances
such as nutrients, water, and
gases from the environment
The stability of the environment
depends on the healthy
functioning of organisms in that
environment
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Metabolism
Sum of all the chemical reactions
in an organism
All require energy
Sunlight is the ultimate energy
for life on Earth
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Metabolism
Cellular Respiration
– Cells releasing the chemical
energy stored in foods
6O2 + C6H12O6
6CO2 + 6H2O
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Organisms Respond to Stimuli
Organisms Respond to stimuli
(Temperature, Water, Food
Supplies, etc.) In Order To
Survive & Reproduce
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Homeostasis
Keeping The Internal Environment
(Homeostasis) Of The Cell or
Organism Within The Ranges Required
For Life
Stable internal conditions of pH,
temperature, water balance, etc.
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Living Things Evolve
Groups Of Organisms
(Not Individuals)
Change Over Time In
Order To Survive
Within Changing
Environments.
Fossil records show
changes in groups of
organisms
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Explains why organisms look and
behave the way they do
Provides a basis for exploring the
relationships among different
groups of organisms
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Natural Selection
Natural selection is the
driving force in evolution
Organisms that have certain
favorable traits are better
able to successfully reproduce
than organisms that lack
these traits
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Natural Selection
Survival of organisms
with favorable traits
cause a gradual change
in populations over many
generations
Copyright Cmassengale
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Life is Organized on
Several Levels
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Levels
Atoms
Molecules
Organelles
Cells – life starts here
Tissues
Organs
System
Organism
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Levels
Population
Community
Ecosystem
Biosphere
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Quiz Next Time!
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