Concept:Homeostasis is the maintenance of a steady internal environment in an organism despite changes in the external environment.
Explanation:A plant growing in a phosphorus-deficient soil still needs phosphorus for essential life processes.
To maintain a constant internal supply, the plant releases phosphorus from older tissues into the phloem.
The phloem then transports this phosphorus to young and actively growing parts of the plant.
As a result, the plant is able to keep its internal phosphorus level fairly stable even though the soil lacks phosphorus.
This internal regulation in response to an external deficiency is a clear example of homeostasis in living organisms.
It shows the plant balancing its internal condition despite the unfavourable condition in the soil.
Answer:The release of phosphorus into the phloem of a plant growing in a phosphorus-deficient soil is the correct example.