The statement that is not true is: A healthy ecosystem can support an unlimited number of life forms.
Any ecosystem has its limits. No matter is a healthy, in perfect shape, and very large ecosystem, there's always a limit as to how much life forms can the ecosystem support. If the number of life forms surpasses the ability of the ecosystem to support them, than the ecosystem will crash, be destroyed, and experience a lot of changes, with the death of lot of life forms involved in the process as well.
There isn't such thing as an ecosystem that has the ability to support an infinite number of life forms, there's only ecosystems that are able to support limited number of life forms.
