One of the challenges that scientists face when classifying a new fossil is that any tiny detail is all that separates one species from another. Further exploration is required to identify another set of characteristics that may help in deciding which organism belongs or create a new class.
Answer:
the defention of environment is the surroundings or conditions in which a person, animal, or plant lives or operates
Explanation:
because the natural world, as a whole or in a particular geographical area, especially as affected by human activity.
Answer: The immune system
Explanation:
The immune system is a complex network of proteins and cells that defends the body against infection or any invasion. The human defense system in the body is actually made up of entire organs and vessel systems like the lymph vessels. The immune system is made up of organs that control the production and maturation of certain defense cells.
Initially, all living things are subjected to attack from disease causing agents. Even bacteria, so small that more than a million could fit on the head of a pin, have systems to defend against infection by viruses. This kind of protection gets more sophisticated as organisms become more complex.
