Transcript What is Life?

What is Life?
Characteristics
Of
Living Things
Organisms
• Any living thing
All Living Things:
• Have cellular organization
• Contain similar chemicals
• Use energy
• Grow and develop
• Respond to the environment
• Reproduce
Cellular Organization
• Unicellular-single celled
organisms such as bacteria
• Multicellular-organisms which
are composed of many cells
Unicellular
Multicellular
Chemicals of Life
• Water-H2O
• Carbohydrates-sugars
• Proteins
• Lipids-fats
• Nucleic Acids-DNA
Energy Use
• All living things use energy for
growth and cell repair
• Energy is used for work-for
example digesting food,
pumping blood and
exchanging gases (breathing)
Growth and Development
• Growth is the process of
becoming larger
• Development is the process of
change that occurs during an
organism’s life-such as healing
and specialization
Response to Environment
• Stimulus-a change
in an organisms
environment that
causes an
organism to react
(such as changes
in temperature,
light sound, etc.)
• Response-an action
or change in
behavior (such as
flinching, shivering,
a plant bending
toward the light)
Reproduction
• Producing offspring that are
similar to the parent organisms
(birds lay eggs, plants make
seeds, bacteria divide into two
exact replicas of the original
bacteria)
Life Comes From Life
• Spontaneous generation- the mistaken
idea that living things arise from nonliving
things
• Francesco Redi-designed a controlled
experiment to disprove spontaneous
generation
• Louis Pasteur-designed an experiment to
show that microorganisms live in the air
Francesco Redi’s Experiment
• Redi Placed meat in jars, one was left uncovered
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and one was covered with cloth
He left the jars out for a few days
The jar that was left open had maggots
The jar that was covered didn’t have any
maggots
He concluded that the flies he had seen had laid
eggs on the meat
His experiment helped to disprove spontaneous
generation
Louis Pasteur’s Experiment
• Pasteur placed broth in two flasks which had
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curved necks which allowed air to enter but not
bacteria in the air
He boiled one flask but not the other one
The flask which had been boiled remained clear,
but the other one spoiled
His experiment showed not only that bacteria is
everywhere, but also that boiling can kill most
bacteria and that bacteria only form when other
bacteria are present
Energy
• Autotrophs-organisms, such as
plants, which can make their
own food
• Heterotrophs-organisms that
cannot make their own food,
they have to ingest food
Autotrophs
Heterotrophs
Water
• All living things need water
• Water is able to dissolve more
chemicals than any other
substance on earth
• Makes up 92 percent of your body
weight
Homeostasis
• The maintenance of stable
internal conditions despite
changes in its surroundings
(like sweating when your hot,
shivering when your cold, or a
plant which goes dormant in
the winter)