Question

Which organisms are called primitive and how are they different from so-called advanced organisms?

Answer 1

Hint: Primitive organisms have a simpler body design whereas advanced organisms are more complex in body design.

Complete step by step solution: To answer this question, at first, we have to know the difference between primitive and advanced organisms. Primitive organisms also are referred to as lower organisms due to the fact they are less complicated and they are prone to undergo changes in their physical functions and structures. For example, single-cell organisms are primitive organisms and the eukaryotic organisms are called to be the advanced form of the primitive organisms. The advanced organisms have higher body functions and they are more complex compared to the primitive organisms. For example, humans are considered as advanced organisms and they have different organs to perform body functions whereas the primitive organisms such as prokaryotes, all the functions are carried out by a single cell.

Additional Information: The very first organisms to have evolved are unicellular organisms. And the very first types of unicellular organisms are prokaryotes. These are organisms that have very primitive cellular features and biological functions. Multicellular organisms such as animals and plants are the most advanced forms of life owing to the multitude of life processes and features that have evolved.
The advanced animals are complex whereas the primitive lives are simple. Advanced life forms have a well structured and well-developed body system. For example - starfish is a more advanced organism than Amoeba.

Note: In organisms, the complexity in the structure of simpler forms has increased over evolutionary time due to which they ultimately become modern complex form.