What are the 5 levels of organization in order?

Biology: Levels of Organization

Organization is the arrangement of smaller components of nay structure, system or situation into larger ones and larger ones into still larger ones in hierarchy, where components of each level coordinate with one another towards a common goal. Organisation is sort of hierarchy or pyramid of levels where each level is made of components of lower level and itself becomes a component of higher level.

1. Atomic level

The basic unit or component of organization in both living and non-living object is an atom. An atom is, of course further made of still smaller particles like electrons, protons and neutrons.

 2. Molecular level

Atoms combine with one another to form molecules Examples are:

•  pure water ( H2O)
•  sodium chloride ( NaCl – also called table salt)
•  glucose ( C6H12O6)
•  proteins
•  carbohydrates
•  lipids

Macromolecules are large, biologically important molecules inside cells.

 3. Cellular Level

The subcellular components coordinate their activities to produce living cells. Living beings are made of one cell (unicellular organisms) or numerous cells (multicellular organisms). Unicellular organisms are more appropriately called acellular organisms.

They are the most abundant of all the living creatures. Unicellular or acellular organisms possess protoplasmic organisation. Multicellular organisms have higher levels of organization like cellular organization (sponges), tissue organization (coelenterates),organ organization and organ system organization.

 4. Tissue Level

In multicellular organisms the cells may be similar (colonial organisms) or organized into distinct functional units called tissue. A tissue is a group of cells with similar structure performing the same function

There are four basic types of tissue found in the human body:

• Epithelial
• Connective
• Muscular
• Neural

 5. Organ Level

Two or more tissues are organized into distinct structures called organs . Organs are specialized for performing one or more functions e.g.  pumping by heart, photosynthesis by leaves.

6. Organ system Level

Two or more organs coordinate their activities towards a common activity e.g. digestive system, respiratory system.

7. Organismic level or Individual level

Living beings are called organisms because they possess high level of organization. They are called individuals as each organism has a distinct interact or individuality.

8. Population level

All the individuals of a species found in an area where they can interact with one another is called population.

9. Community level

The populations of different species found in an area also interact with one another . They constitute a biotic community.

10.  Ecosystem Level

The biotic community of an area and its abiotic environment together form an ecosystem.

11. Biosphere level

All the ecosystems of the world interact further and form biosphere or livable space of the earth. An organism is, therefore, not only an individual but also a part of population, community, ecosystem and biosphere.

Biosphere has the highest level of organization. Organizations at level of individual and above are known as higher levels of organisation.

It represents ecological hierarchy. Organizations below the level of individual (organ system, organ, tissue, cell, molecules, atoms ) are called as lower level of organization.

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Updated October 07, 2019

By Nikole Yearout

Biology is the study of life. Since life is such a broad topic, scientists break it down into several different levels of organization to make it easier to study. These levels start from the smallest unit of life and work up to the largest and most broad category.

The levels, from smallest to largest, are: molecule, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere.

Molecules are made of atoms, the smallest unit of chemical elements. They can be found in all matter, living and non-living. Molecules make up the most basic structures of living beings. Two biological disciplines that focus on this level are biochemistry and molecular biology.

A cell is the basic unit of life. There are two kinds of cells: plant cells, which have a rigid cell wall made of cellulose molecules, and animal cells, which have flexible cell membranes. Cell biologists consider questions such as metabolism and other questions about structure and function within and between cells.

Tissue is made of cells that work together to perform a certain task. Muscle tissue, connective tissue, and neural tissue are some types of tissue. Histologists are an example of biologists who work at this level.

An organ is a system of tissues that work together on a larger scale to do certain jobs within an animal's body. Examples of organs are the brain, heart and lungs. Anatomy is an example of a biology specialty concerned with this level.

An organ system is a group of organs that work together to perform specific bodily functions. The respiratory system, for example, uses the lungs, airways and respiratory muscles to inhale oxygen and release carbon dioxide in animals. Physiologists study the function of parts of the body as they work together. Though physiologists can work at any level of biological organization, they often answer questions related to organ systems.

An organism is a recognizable, self-contained individual. Organisms can be unicellular organisms such as bacteria or amoebae, or multi-cellular organisms comprised of organs and organ systems. A human being is an example of a multi-cellular organism.

A population is a group of multiple organisms of the same species within a specific area. For example, a pride of lions in Kenya, Africa, is a population.

A community consists of all the different species within a certain area. The population of lions in Kenya, plus the populations of gazelles, giraffes, elephants, dung beetles, and all other species in that area, add up to a community.

An ecosystem is made up of all the communities in a certain area, as well as all the non-living, physical components of the environment. Rocks, water and dirt are a part of an ecosystem. Ecologists may study populations, communities, or whole ecosystems.

The biosphere is all of the ecosystems on Earth added together. Every animal, plant, bacteria, rock, and molecule is a part of the Earth's biosphere. Non-biologists, such as meteorologists and geologists, may join biologists to answer questions at this level of biology organization.

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The diagram shows five levels of organization in a multicellular organism. The most basic unit is the cell; groups of similar cells form tissues; groups of different tissues make up organs; groups of organs form organ systems; cells, tissues, organs, and organ systems combine to form a multicellular organism.

© Encyclopædia Britannica, Inc.