Final answer:
A monophyletic group, also known as a clade, is a group of organisms that includes an ancestor and all of its descendants. It is based on the evolutionary relationships between organisms.
Step-by-step explanation:
A monophyletic group is a group of organisms that includes an ancestor and all of its descendants. It is also known as a clade. This classification is based on the evolutionary relationships between organisms. All organisms within a monophyletic group share significant genetic similarities and external/internal characteristics.
For example, consider the animal kingdom. Animals belong to different clades, such as mammals, birds, reptiles, amphibians, and fish. Each of these clades includes an ancestor and all of its descendants.
It is important to note that a monophyletic group is different from a paraphyletic group or a polyphyletic group, which do not include all descendants or share a common ancestor.