As we know, the cell is the smallest structural and functional unit of an organism. There are mainly two types of organisms, divided according to the cell. Organisms that have a single cell are unicellular, while organisms that have many cells are known as multicellular. Unicellular organisms are simpler in nature, as they mainly depend on the diffusion process for different functions, and have a single cell to perform the different functions of life. On the other hand, the multicellular organism is more complex and has numerous specialized cells that are assigned to perform specific functions within the body. Since unicellular organisms are unicellular, they are smaller in size compared to multicellular ones.

Comparative chart

What is the unicellular organism?

Organisms made up of a single cell are known as single-celled organisms. The unicellular organism has a short lifespan since the only available cell has it for different tasks at the same time. In other words, we can say that due to the workload of the cell, the unicellular organism has a short life. It would be pertinent to mention here that cell injury can even lead to the death of single-celled organisms. Single-celled organisms have a lower ratio of surface area to volume, therefore, the cell body cannot reach the large size within the body of the organism. Unicellular organisms are classified mainly into four groups; archaea bacteria, protozoa, single-celled algae, and single-celled fungi. What’s more, single-celled organisms fall into two general categories: eukaryotic organisms and prokaryotic organisms. The single-celled organism is known as one of the ancient life forms, which was simpler in nature and was sufficient for the survival and reproduction of organisms at that time. According to famous biologists, the single-celled organism existed about 3.8 million years ago. The single cell in them regulates all the functions of the body, making it difficult for them to survive. One of the main reasons for its short life is the exposure of the cell to the environment. Single-celled organisms are quite smaller, so they cannot even be seen with the naked eye. Amoeba and Paramecium are some of the prominent examples of single-celled organisms. According to famous biologists, the unicellular organism existed about 3.8 million years ago. The single cell in them regulates all the functions of the body, making it difficult for them to survive. One of the main reasons for its short life is the exposure of the cell to the environment. Single-celled organisms are quite smaller, so they cannot even be seen with the naked eye. Amoeba and Paramecium are some of the prominent examples of single-celled organisms. According to famous biologists, the single-celled organism existed about 3.8 million years ago. The single cell in them regulates all the functions of the body, making it difficult for them to survive. One of the main reasons for its short life is the exposure of the cell to the environment. Single-celled organisms are quite smaller, so they cannot even be seen with the naked eye. Amoeba and Paramecium are some of the prominent examples of single-celled organisms. that cannot even be seen with the naked eye. Amoeba and Paramecium are some of the prominent examples of single-celled organisms. that cannot even be seen with the naked eye. Amoeba and Paramecium are some of the prominent examples of single-celled organisms.

Organisms that consist of more than one cell are known as multicellular organisms. Multicellular organisms are made up of numerous cells that depend on the complexity and size of the organism. For example, human beings are one of the most complex multicellulars, we have about 37.2 trillion cells in our body. Of the numerous cells, many of them are specialized cells that perform the specific task assigned to them. In our body, these cells combine with each other to form tissues, and then the tissues combine to form the different organs within the body of the organism. Some of the prominent specialized cells in the human body that are assigned to perform the specific task are muscle cells, nerve cells, and blood cells. The multicellular organism is comparatively large and is mainly visible to the naked eye. At the same time, multicellular cells have a longer service life, since the cells have no workload, since the division of labor is available to them. In addition, they have the type of specialized cells to deal with the external environment. Multicellular organisms also started once from a single cell and then grew to host the numerous cells. They have the kind of specialized cells to deal with the external environment. Multicellular organisms also started once from a single cell and then grew to house the numerous cells. They have the kind of specialized cells to deal with the external environment. Multicellular organisms also started once from a single cell and then grew to house the numerous cells.

Unicellular organism versus multicellular organism

• The body of the unicellular organism is made up of a single cell, while the body of the multicellular organism is made up of more than one cell.
• Unicellular organisms have a shorter life compared to multicellular organisms.
• The unicellular organism is the smallest area, that most of them are not even visible to the naked eye. On the other hand, the multicellular organism is large and most of them are easily visible with the naked eye.
• The divisions of labor in single-celled organisms are at the level of organelles, while the division of labor in multicellular organisms is at the level of tissues, organs, and systems.
• Available individual cells carry out all life processes in single-celled organisms. In contrast, multicellular organisms have specialized cells to perform different tasks.