Question

how does active transport help maintain cellular homeostasis?
degrading foreign dna
removing excess protein products
maintaining proper molecule concentrations

Explanation:

Active transport is a process that moves molecules against their concentration gradient, using energy. Cellular homeostasis refers to the stable internal environment of a cell. By moving molecules (such as ions) into or out of the cell as needed, active transport helps maintain the proper concentrations of these molecules inside and outside the cell. This is crucial for various cellular functions like nerve impulse transmission, muscle contraction etc. Degrading foreign DNA is more related to processes like restriction - modification systems in bacteria (not directly active transport). Removing excess protein products is more about protein degradation pathways (like the proteasome pathway) rather than active transport.

Answer:

maintaining proper molecule concentrations