Question

1. The following explains why the kidneys do not have an active (uses ATP) absorption mechanism for iron ions:

   		iron ions can diffuse across membranes: hence they are passively reabsorbed.
   		iron ions cannot pass the glomerular basement membrane because of their charge: hence no need to reabsorb.
   		iron ions in the plasma are not filtered because they are bound to proteins: hence no need to reabsorb.
   		none of the above.

Answer 1

none of the above
Explanation:
Kidney plays a significant role in iron absorption and maintaining homeostasis but kidney do not have an active ATP uses mechanism for iron ion absorption as they are absorbed by secondary active transport ,It is the transport of a solute in the direction of its electrochemical gradient and it does not directly require ATP. here two different molecules will interact with a single membrane transporter that has to be be translocated across the cell membrane.