Here! I reposted the question!

I would say without it, the nutrients would not be able to get anywhere.

Explanation:

Blood is like a river. Say in the bottom of that river are pebbles. The beavers down the stream need those pebbles,they are essential. But say one day the river stops flowing(the blood in our body) and nutrients aren't going where their supposed to be. Then the  places that need those nutrients aren't getting them. Then its all chaos.

Hope this helps. I really want brainliest!  :)

when it gains or loses electrons

i think its c if i'm wrong