Kangaroo Biology question

A kangaroo rat is a mammal that lives in hot desert regions of America.
In Kangaroo rats, the tissue surrounding the collecting duct contains a high concentration of ions. Explain how this feature enables kangaroo rats to survive in the desert (3 marks).

Reply 1

username3724872

Haven't done Biology in months but I hope this helps:
High concentration of ions mean low water potential in the tissue, which causes water molecules to diffuse from an area of high water potential (or water concentration if you're doing GCSE) to an area of low water potential. This ensures that the kangaroo rat collects as much water, in the collecting duct, as possible, despite not having a large source from the environment.
PLEASE NOTE: I have no idea what the mark scheme says so please check with the mark scheme.