Beyond organism level, there are still higher levels of organization. The following higher levels of organization can be recognized.
Each organism is a member of a particular species. All the members or individuals of a particular species found in locality constitute a population. For example, you are an individual of the species Homo sapiens. All the members of your family will constitute the population of Homo sapiens in your family. The total number of Homo sapiens (including men, women, children) found in a city, district, state etc., constitute the population of that city, district, state. The population of a single species can interbreed to produce fertile offspring.
A group of organisms of the same species, within which individuals may exchange genetic information, is known as population.
Let us consider a given area such as a pond, a field or garden. In a pond, you will get different kinds of plants like algae, higher plants (hydrophytes), insects, animals, fish and many other living organisms. Theses constitute a biotic community. The community is considered the next higher level of organization. In other words, several populations of different species living together make a biotic community.
The biotic community as a whole is dependent upon the nonliving or physical world for its survival. For example, plants and animals of a pond survive in water. Their survival also depends upon temperature, light, pH, gases, nutrients, etc. The biotic community of any geographical area such as forests, deserts, grasslands, mountains, oceans interacts with the physical environment of that place to form an ecological unit, or ecosystem. This is the next higher level of organization.
A group of ecosystems forms a biome. Grassland, desert, sea, etc., are biomes. All the biomes on the earth constitute the biosphere. This level is the highest level of organization which includes all the zones of the world where life exists.
The planet earth along with its living organisms and atmosphere which sustains life is called biosphere.
Go to a filed. Observe and note down the types of organisms present there. Record the number of populations of these organisms. Categorize them into plant and animal populations.
Basis of Levels of Organization
It is clear from the above account that various levels of organization constitute the living world. Levels of organization in living beings can be seen in their structures and functions as well. The organization of living organisms at a given level is based on the following basic principles.
1. One of the basic principles of organization is aggregation. For example, molecules are formed by the aggregation of atoms. Molecules form cells which aggregate in an orderly sequence to form an individual. A population is formed by the aggregation of individuals. Various kinds of populations aggregate to form biotic community which in turn interacts with biotic materials to form ecosystems. All the ecosystems aggregate to form the biosphere.
2. The number of interacting substances decreases as we move from lower to higher levels of organization. For example, there are fewer communities than species.
3. At higher level of organization, the system becomes more complex in its structure and function. Higher level of organization encompasses the complexity of all the lower levels but has some additional features of its own.
4. Although the unit of a particular level of organization remains independent in respect of its activity, it becomes restricted in function when it is adopted by higher level of organization.
5. Every step of the level of organization has its own specialized structure and function. For example, flowers and leaves both are the parts of the shoot system but their structures and functions are different.
6. Collective and co-ordinate interaction leads to a higher level of organization. The formation of next higher level of organization is not possible in absence of co-operative interactions.
7. The molecular level and below represent the interactions between nonliving matters while the cellular level and higher levels of organization are living.
8. Any damage or disruption caused at a higher level may or may not affect the lower levels of organization. For example, disruption or damage to a part of a population would not mean that all individuals of the population would die.
9. Energy is required to reach the next higher level. For example, it requires energy to create cells out of molecules.