See this is due to reason that mitochondria and ribosome etc are part of cell but they are not directly working for body see if you have studied physics then maybe you have heard that atom is the smallest unit but we also know that they are made of proton , neutron etc thats why
if you understood then please upvote

The cell is called the smallest unit of the body because it is the basic structural and functional unit of all living organisms. The cell is the building block of tissues, organs, and systems in the body. The human body is made up of trillions of cells, each performing a specific function and working together to keep the body healthy.

Size of cell compared to organelles

Although there are organelles in the cell that are smaller than the cell itself, these organelles cannot survive or function independently without the cell. For instance, mitochondria, which are responsible for energy production in the cell, cannot survive without the cell. Similarly, centrosomes, which are involved in cell division, cannot function without the cell.

Functions of cells

Cells have various functions, including:

1. Maintenance of homeostasis: Cells help to maintain the internal environment of the body by regulating the levels of ions, nutrients, and other substances.

2. Energy production: Cells produce energy in the form of ATP through various metabolic pathways.

3. Reproduction: Cells are responsible for the reproduction of organisms through cell division.

4. Communication: Cells communicate with each other through various signaling pathways to coordinate their functions.

Conclusion

In conclusion, the cell is called the smallest unit of the body because it is the basic building block of all living organisms. Although there are organelles in the cell that are smaller than the cell itself, these organelles cannot function on their own without the cell. Cells have various functions, including maintenance of homeostasis, energy production, reproduction, and communication.