Sunday Emmanuel

@sundayemmanuel · 26 Nov 2021

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What is an organism

An organism is an individual form of life that is capable of growing and reproducing, and has one or more cells. Animals, plants, and bacteria are all organisms. All of these cells come from pre-existing cells, and multi-cellular organisms have specific cells for different functions. Inside the body, organelles or organs work together to sustain life. Organisms can also respond to stimuli, grow and maintain homeostasis.

There is an increase in complexity from unicellular organisms to multicellular organisms. Even though unicellular organisms can perform all Life processes, they still lack vital tissue, organs, or systems that are efficient and capable of ensuring their survival. As a result of this, higher organisms have advantages and some disadvantages in complexity over unicellular organisms.

Advantages of complexity in higher organisms

Complexity lead to efficiency: complexity makes higher organism to be efficient in carrying out Life processes.
It increases adaptation to the environment: complexity makes higher organisms more resistant to adverse conditions within the environment
It leads to cellular differentiation: as a result of complexity, groups of similar cells are differentiated to form tissue that carries out similar functions.

Disadvantages of complexity in higher organism

It leads to the slow rate of diffusion: complexity leads to the slow rate of diffusion of oxygen or respiratory gas to an individual cell.
Decrease in ability to regenerate: the ability to regenerate decreases with the complexity of organisms.
In the ability of individual cells to exist on their own: in complexity, cells lose their independence and become increasingly dependent on one another activities.

Groups of organisms

Viruses: viruses are noncellular organisms without a nucleus cytoplasm and cell membrane. They are invisible under the highest magnification of a light microscope. They can only be seen under an electron microscope.


Bacteria: bacteria are unicellular organisms of microscopic size the largest plane about 12 microns (1 micron=0.001 mm) long and about 1.5 microns in width. Bacteria can be seen with a light microscope. Van Leeuwenhoek first discovered bacteria in 1683.


Fungi: fungi are nongreen simple plants. They are mostly parasitic or saprophytic in nutrition. Parasitic fungi live in or on the tissue of their host while the saprophytic forms obtain their food from dead and decaying material.


Protozoa: protozoa are microscopic and unicellular organisms found in both marine and freshwater and damp soil. Some are free-living (e.g. Amoeba Proteus, paramecium caudatum) while others are parasitic (e.g.plasmodium, Entamoeba histolytica, and Trypanosome).@Henkjan de Krijger #whatisanorganism #advantagesofcomplexityinhigherorganism #disadvantagesofcomplexityinhigherorganism