cell is the smallest level of organization in a unicellular organism
From smallest to largest, a multicellular organism can be organized into cells, tissues, organ systems, and organisms.
Multicellular organisms have 5 levels of organization ranging from simplest to most complex...cells, tissues, organs, organ systems, organisms.
The first level of organization are living cells. The second level of organization are tissues. The third level of organization is an organ. The fourth level of organization is the organ system. The last level is organisms.
The highest level of organization a sponge has are Cells.
The main difference between unicellular organisms and multicellular organisms is that unicellular organisms are made up of a single cell, while multicellular organisms are made up of multiple cells that are specialized to perform different functions. Multicellular organisms have a higher level of complexity and organization compared to unicellular organisms.
The organism. The levels of organization of an individual from smallest to greatest are: atoms, molecules, cells, tissues, organs, organ systems, and organism. Not all organisms have all levels of organization, such a bacteria, protists, sponges, and more.
The level of organization not found in all living things is the tissue level. While all organisms consist of cells, not all, such as unicellular organisms like bacteria and protozoa, have tissues. Tissues are a complex organization of similar cells that work together for specific functions, which is characteristic of multicellular organisms.
an Organ System
Protists are typically organized at the cellular level, as they are unicellular organisms. They can also form colonies or multicellular structures in some cases, but their primary level of structural organization is at the cellular level.
In what is possibly the most extremely unsatisfying answer, we don't actually know. As microscopes get more and more powerful, we are discovering incredible amounts of structure at the sub-atomic level. Despite this, the common label for the smallest physical organization in ecology is simply "Organisms". At one point we thought that things couldn't get much smaller. Now we are finding vast factories with unprecedented order as we look closer at even single-celled organisms.
...they lack the distinct organization and coordination found in true tissues and organs of higher organisms. Specialized regions in multicellular protists do not have the same level of structural complexity and integrated function as tissues and organs in organisms with more advanced levels of organization.
Multicellular organisms are made up of specialized cells that work together to form tissues and organs, while colonies of unicellular organisms consist of individual cells living in close proximity but maintaining their independence. Multicellular organisms have a higher level of organization and coordination compared to colonies of unicellular organisms.