Difference Between Unicellular and Multicellular Organisms

The one element taxonomy that scientists use to categorize all living organisms into groups based on certain characteristics. In this, taxonomy can be broken down into more specific kingdoms. In all, there are six kingdoms and four of these four types can further be divided into two groups such as Eukaryotic or prokaryotic organisms.

Eukaryotic organisms

This organism is unique because it can be both unicellular and multicellular. To fit this category, a cell must have membrane-bound organelles. These cells have a nucleus that consists of DNA, mitochondria for energy, and other organelles to carry out the cell functions. Eukaryotes include mammals, plants, fungi, and protists.

(Image will be uploaded soon)

Prokaryotic Organisms

On the other hand, prokaryotes consist of a single cell with no membrane-bound organelles. This organism has to adopt other ways of carrying out reproduction, feeding, and waste excretion.  Bacteria, archaea, and cyanobacteria are examples of prokaryotes.

(Image will be uploaded soon)

What is a Unicellular Organism?

A unicellular organism is an organism that is made up of a single cell and the life processes such as reproduction, feeding, digestion, and excretion occur in one single cell. There are some examples of unicellular organisms like Amoeba, bacteria, and plankton. These unicellular organisms are typical microscopic which cannot be seen with naked eyes. Unicellular organisms are of different types including bacteria, protozoa, and unicellular fungi. Asexual reproduction is famous among unicellular organisms. To make you more understanding, below are the details of types of bacteria.

(Image will be uploaded soon)

Types of Unicellular Organisms

Bacteria

The structure of bacteria is too tiny and every bacterial cell is different from an animal and plant cell. The size of the bacterial cell is about micrometres across. Even bacteria are of a single cell but it consists of different parts like Chromosomal DNA, Plasmid DNA, Cell Wall, Cell Membrane, and Flagellum.

Protozoa

It is a type of unicellular organism that lives in water or in damp places. Protozoa have an adaptation that it behaves like an animal a bit. It produces pseudopodia that let it move to surround food and let it take inside the cell. Once the process of taking food inside is done, contractile vacuoles appear inside the cell then combine with the surface to remove waste.

Yeast 

Yeast is another type of unicellular fungi. It may be possible you are familiar with seeing mushrooms and toadstools. Yeast has cell walls like plant cells and no chloroplasts which mean sugar is the main nutrition for them as they are not able to make their own food by photosynthesis. 

Cyanobacteria

The cyanobacterium is also known as Blue-Green Algae (BGA). It is the process of characteristics of both bacteria and algae. It resembles algae as photosynthesis for food production whereas the prokaryotic nature of BGA forms it similar to bacteria. Other than this, diatoms, euglena, chlorella, and Chlamydomonas are included in the example of cyanobacteria. 

Functions of Unicellular Organisms

There are many unicellular organisms that live in extreme environments like hot springs, thermal ocean vents, polar ice, and frozen tundra. These unicellular organisms are called extremophiles. This unicellular organism is specially adapted to live in places where multicellular organisms cannot survive because they are resistant to extremes of temperature or pH. Although, not every unicellular organism are extremophile because many live under the same range of living condition as multicellular organisms, but still necessary things to all life forms on earth. For instance, phytoplankton is a type of unicellular that lives in the ocean. 

What are Multicellular Organisms?

A multicellular organism, tissue, or organ is an organism that is made up of many cells. Animals, plants, and fungi are multicellular organisms. Multicellular organisms are much bigger in size and are very complex and intricate in their composition along with structure. Human beings, animals, plants, insects are examples of multicellular organisms. 

Examples of a Multicellular Organism

These organisms delegate biological responsibilities like barrier function, digestion, circulation, respiration, and sexual reproduction to a particular organ such as the heart, skin, lungs, stomach, and sex organs. These organs are composed of many different cells and cell types that work together to perform a particular task. For instance, cardiac muscle cells have more mitochondria than produce adenosine triphosphate to beat and power the circulation of blood through a circulatory system. 

(Image will be uploaded soon)

Organisms

Organisms are made up of numerous cells that are categorized as multicellular organisms. The formation of unicellular organisms took one billion years to appear on the planet. Humans are the best example of multicellular organisms that are created by the fusion of two single cells specialized for sexual reproduction commonly producing an egg and the sperm. 

Only fusion is the single egg gamete with a single sperm leads to the formation of a zygote or fertilized egg cell. The zygote contains both sperm and egg which are the genetic material. 

Plants

Plants are mostly photosynthetic eukaryotes belonging to the Plantae kingdom. Plants are multicellular organisms in the majority of cases. Photosynthesis by primary chloroplasts formed from endosymbiosis with cyanobacteria provides the majority of the energy for green plants. Some plants are parasitic or mycotrophic, meaning they lack the capacity to make chlorophyll or photosynthesize yet nevertheless produce blooms, fruits, and seeds. Sexual reproduction and generational alternation are prevalent in plants, however, asexual reproduction is also common.

Let us learn more in detail with the help of differentiation between organisms and multicellular organisms. 

Difference between Unicellular and Multicellular Organisms