Tuesday, March 31, 2009

What are the Hierarchical Levels of Life Forms

Life on Earth is incredibly extensive and to make it easier to study, biologists have broken living systems up into generalized hierarchical levels as given below:

1) Molecules
2) Organelles
3) Cells
4) Tissues
5) Organs 6) Organisms
7) Populations
8) Communities
9) Ecosystems
10) Biosphere

The lowest level of the biological hierarchy begins with molecules. Examples include proteins, DNA, lipids, etc. Many such specialized molecules are organized into cells, the basic unit of life. There are single-celled organisms such as bacteria, amoeba, yeast, etc., in which the body consists of a single cell. When the body consists of more than one cell it is called multicellular. Multicellular organisms are collection of various types of specialized cells. A group of specialized cells carrying out a specific function is called a tissue. For example, muscle tissue, nervous tissue, connective tissue, etc. When different types of tissues are organized together to perform a common function it is called an organ. Examples include, liver, stomach, heart, etc. When a number of organs function together to accomplish a specific function of the body, it forms an organ system. For example, the stomach, liver, intestine, pancreas, salivary glands, etc. work together to form the digestive system. In an organism there are a number of organ systems that work in an associated way to form the organism and its life activities. Each individual organism is a member of a large population, which exists in a habitat.

A population is a group of organisms belonging to a species. A group of different species that live and interact in a particular area or environment is known as a community. The communities, along with the environment in which they exist, are known as ecosystems. An ecosystem consists of biomes, which are large geographical areas of the world. Each biome is a part of the biosphere, which includes the entire living population on the Earth along with its physical environment.

Tags: Bio Technology, Bio Genetics , Life Forms, organisms

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