“Characteristics of Life and
Energy”
“Characteristics of Life #1”
Define biology.

Biology is the study, or science, of life.
Define life.


Life => 48 entries found.
Why is a definition of life needed? What is life?
If this strikes you as an odd question, consider it
for a moment. Of course we all have an
intuitive sense of what life is, but how would you
actually define it? Given the incredible diversity
of living things, from the mold on your old tuna
sandwich to monkeys in the rainforest, how
could one word encompass all that "life"
represents? Even biologists have a difficult time
defining the very concept they study. However,
given our knowledge of the life forms present on
Earth, it is recognized that all living things do
share a set of characteristics in common.
List the Characteristics of Life
1. Organization
All living things (organisms) are organized. This means
they are specially designed to perform different life
functions. The smallest level of organization of living
things is cells. Cells are the smallest unit of life.
2. Reproduction
All organisms have the ability to reproduce. Organisms
produce new organisms that are similar to them.
3. Adjust to Surroundings
All organisms have the ability to adjust (change) to their
surroundings--that is, organisms respond to stimuli. For
example, if a flea made a dog's nose itch (the stimulus),
the dog would scratch its nose (response to stimulus).
List the Characteristics of Life
4. Growth and Development
Organisms grow (increase in size). When they grow,
they go through changes known as development.
5. Require energy, water and minerals
All organisms need these items to function. If they do
not get any of these, the organisms die.
 If something does not have all of the
characteristics listed above, then it is not a
living thing!
Structural Organization of Living
Organisms
1. Atom = the smallest particle that
maintains its physical and chemical
properties
2. Molecule = when two or more atoms
are bonded together
3. Macromolecule = when two or more
molecules are bonded together to form
large (gigantic!) molecules
 Natural examples include proteins,
starches, lipids and nucleic acids (such
as DNA).
Structural Organization of Living
Organisms
4. Organelle = one of several structures
with specialized functions, suspended in
the cytosol of a eukaryotic cell.
5. Cell = the smallest unit of life, a cell is a
collection of organelles functioning
together.
 Some organisms, such as bacteria, are
unicellular, consisting of a single cell.
 Other organisms, such as humans, are
multicellular.
Structural Organization of Living
Organisms
6. Tissue = a collections of cells
working together to perform a
specific job.
7. Organ = a group of tissues which
perform a specific function or group
of functions.
 Common animal organs include the
heart, lungs, brain, eyes, stomach,
spleen, pancreas, kidneys, liver,
intestines, skin, uterus, bladder,
bone, etc.
Structural Organization of Living
Organisms
8. Organ system = a system composed of organs
working together to carry out a function.
 examples:
Circulatory system
Digestive system
Endocrine system
Immune system
Integumentary system
Lymphatic system
Muscular system
Nervous system
Reproductive system
Respiratory system
Skeletal system
Urinary system
Structural Organization of Living
Organisms
9. Species/organism= the basic unit of
biodiversity/several organ systems functioning
together.
10. Population = groups of individual organisms
of the same species working together to achieve
a common goal.
11. Community = the bringing together of living
things that share an environment. The individual
living beings can be plant or animal; any
species; any size.
Structural Organization of Living
Organisms
12. Ecosystem = an abbreviation of the term ecological
system. They can be as big as the Sahara desert, but as
small as a pond.
 Groups of different populations living in the same
environment.
 Balance is achieved through various types of symbiosis-predation, parasitism, mutualism, commensalism,
competition, and amensalism. Introduction of new elements,
whether abiotic or biotic, into an ecosystem tend to have a
disruptive effect.
 Different ecosystems are often separated by geographical
barriers, like deserts, mountains or oceans, or are isolated
otherwise, like lakes or rivers. As these borders are never
rigid, ecosystems tend to blend into each other. As a result,
the whole earth can be seen as a single ecosystem, or a lake
can be divided into several ecosystems, depending on the
scale used.
Structural Organization of Living
Organisms
13. Biosphere = that part of a planet's
outer shell--including air, land, surface
rocks and water--within which life occurs.
 The biosphere is the global ecological
system integrating all living beings and
their relationships, including their
interaction with the elements of the
lithosphere (rocks), hydrosphere (water),
and atmosphere (air).