Levels of Organisation in Animal kingdom – Class 11 | Chapter – 4 | Short Notes Series PDF

Levels of Organisation in Animal kingdom: The animal kingdom is also classified on the basis of the level of organization other than symmetry, germ layers, and body cavity.  Though the animals are multicellular, the level of organization varies from cellular and tissue level.


Levels of Organisation in Animal kingdom

Cellular level

The cellular level is the most important level. A cell is the crucial unit of life and the littlest unit equipped for increasing itself. While the design and capacity of cells shift significantly contingent upon the living being, all cells share a couple of cells. Cells are made out of natural atoms, contain nucleic acids (like DNA and RNA), are loaded up with cytoplasm, and have a lipid-based film. Cells additionally have many designs called organelles inside their cytoplasm that fill different cell roles.  

Tissue level 

Tissue is the most important layer that plays a major role in the protection of the organ, and tissues allow only the required one into the organ and keep the organ safe.

Tissues are groups of similar cells from the same origin that work together to perform a specific function. Basic tissues in humans are classified into  Connective tissues, which are made up of fibrous cells that give organs shape and structure. Muscle tissue is composed of cells that can contract and allow  moving 
The outer layers of organs, the skin, and the stomach are made up of epithelial tissues. Nervous tissue, the spinal cord, and the brain is made up of specialized cells that transform information through electrochemical signals.

Organ level

An organ is a structure composed of various tissues that carry out specific bodily functions. Most organs contain tissues. The organ level is composed of the level combination of tissues together in one to perform a specific function.  Organs can be solid or hollow, and their size and complexity vary greatly. Organs include the heart, lungs, and brain next to this level organism level and which is a very complex level is composed of different organs to perform a particular thing to maintain the body 

Organ systems in different groups of animals exhibit various patterns of complexities. For example, the digestive system in Platyhelminthes has only a single opening to the outside of the body that serves as both mouth and anus, and is hence called incomplete. A complete digestive system has two openings, mouth and anus. Similarly, the circulatory system may be of two types:
(i) open type in which the blood is pumped out of the heart and the cells and tissues are directly bathed in it and
(ii) closed type in which the blood is circulated through a series of vessels of varying diameters (arteries, veins and capillaries).

However, there are arguments in the scientific community that there are three additional levels of structural organization.

These are

  • Atomic or chemical level of organization

  • Cell organelle level of organization

  • Organism level of organization

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By Team Learning Mantras