The hierarchy of biological organization extends from the smallest level of atoms and molecules, up to the largest level of the biosphere. It includes cells, tissues, organs, organ systems, organisms, populations, biocenoses, ecosystems, biomes, and ultimately the biosphere. Each level provides the structural and functional basis for organization at the next level up in the hierarchy.

1. The Hierarchy of Biological
Organization
Wilson, Avierosse D

2. What is Biological Organization?
Biological organization is the hierarchy of
complex biological structures and systems that
define life using a reductionistic approach. The
traditional hierarchy extends from atoms to
biospheres.

3. ATOM
MOLECULE
CELL
ORGANELLES
CEL
L
TISSU
E
ORGAN
SYSTEM ORGANS
ORGANISM
POPULATIO
N
BIOCENOSE
S
ECOSYSTE
M
BIOME
BIOSPHERE

4. Atom
An atom is the smallest constituent unit of
ordinary matter that has the properties of a
chemical element. Every solid , liquid, gas
and plasma is composed of neutral or
ionized atoms. Atoms are very small; typical
sizes are around 100 pm (a ten-billionth of a
meter, in the short scale). However, atoms
do not have well-defined boundaries, and
there are different ways to define their
size that give different but close values.
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6. Molecule
A molecule is an electrically neutral
group of two or more atoms held
together by chemical bonds.]Molecules
are distinguished from ions by their
lack of electrical charge. However,
in quantum physics, organic chemistry,
and biochemistry, the term molecule is
often used less strictly, also being
applied to polyatomic ions.
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8. Cell Organelles
An organelle is a specialized
subunit within a cell that has
a specific function. Individual
organelles are usually
separately enclosed within
their own lipid bilayers.
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10. Cell
The cell is the basic structural,
functional, and biological unit of
all known living organisms. A cell
is the smallest unit of life that
can replicate independently, and
cells are often called the "building
blocks of life". The study of cells
is called cell biology.
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12. Tissue
A tissue is a cellular organizational
level intermediate between cells and
a complete organ. A tissue is an
ensemble of similar cells from the
same origin that together carry out a
specific function. Organs are then
formed by the functional grouping
together of multiple tissues.
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14. Organ
An organ or viscus is a
collection of tissues joined in a
structural unit to serve a
common function. In anatomy,
a viscus is an internal organ,
and viscera is the plural form.
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16. System of Organs
An organ system is a group
of organs that work together
to perform one or more
functions. Each does a
particular job in the body, and
is made up of certain tissues.
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18. Organism
An organism is any contiguous living system, such
as an animal, plant, fungus, or bacterium. All known
types of organisms are capable of some degree
of response to stimuli, reproduction, growth and
development and homeostasis. An organism consists
of one or more cells; when it has one cell it is known
as a unicellular organism; and when it has more than
one it is known as a multicellular organism. Most
unicellular organisms are of microscopic size and are
thus classified as microorganisms. Humans are
multicellular organisms composed of many trillions of
cells grouped into specialized tissues and organs.
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20. Population
A population is a summation
of all the organisms of the
same group or species, which
live in a
particular geographical area,
and have the capability of
interbreeding.
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22. Biocenoses
A biocenoses coined
by Karl Möbius in 1877,
describes the interacting
organisms living
together in a habitat.
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24. Ecosystem
An ecosystem is a community of living organisms
in conjunction with the nonliving components of
their environment (things like air, water and mineral
soil), interacting as a system. These biotic
and abiotic components are regarded as linked
together through nutrient cycles and energy
flows. As ecosystems are defined by the network of
interactions among organisms, and between
organisms and their environment, they can be of
any size but usually encompass specific, limited
spaces (although some scientists say that the
entire planet is an ecosystem).
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26. Biome
A biome is the formation
of plants and animals that have
common characteristics due to
similar climates and can be found
over a range of continents.
Biomes are distinct from habitats,
because any biome can comprise
a variety of habitats.
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28. Biosphere
The biosphere is the global sum of
all ecosystems. It can also be termed as the zone
of life on Earth, a closed system (apart from solar
and cosmic radiation and heat from the interior of
the Earth), and largely self-regulating. By the
most general biophysiological definition, the
biosphere is the global ecological system
integrating all living beings and their relationships,
including their interaction with the elements of
the lithosphere, geosphere, hydrosphere,
and atmosphere.
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