Final answer:
Protozoa are more closely related to humans than to trees on the evolutionary tree, as they are single-celled eukaryotes with traits that align them with animals, despite not being animals themselves. They share a common ancestor with eukaryotic organisms like animals, but are distinct from plants.
Step-by-step explanation:
On the evolutionary tree, protozoa are more closely related to humans than to trees. Protozoa, which are single-celled eukaryotes, are considered to be some of the earliest ancestors of animals. They are categorized under the domain Eukarya, which encompasses all organisms with complex cells, including humans. While protozoa are not animals themselves, they share a more recent common ancestor with animals, including humans, than they do with plants.
When studying a phylogenetic tree that maps out evolutionary history, we can see that all eukaryotic organisms, such as animals, plants, protists, and fungi, diverge from a common ancestor. The branches of this tree illustrate how different groups evolved over time. Notably, protozoa occupy a branch that is separate from that of plants like trees, indicating that, despite their fundamental differences with humans, they are still more similar to humans in the grand scheme of evolutionary history.
Understanding the ecology of protozoa also provides insights into their biological roles. They serve as predators, herbivores, decomposers, and even parasitic agents in various ecosystems. Their method of obtaining nutrients and their cellular structures, which enable them to move and consume food, are features that help us relate them more to animal life forms than plant life forms.