Single celled organism living in fresh water must have specialized organelles to?

Question

a retain salts

b pump water out

c retain water

d expel salts

??

Thanks

Answer 1

Either a or b, most likely b.  Organisms that live in water that is less concentrated than their bodies tend to gain water and lose salts.  Often, salts cannot move through the cell membrane, so the most likely answer is b, because the organisms natural mechanisms try to maintain the normal concentration of its body fluids.  

Answer 2

b pump water out

This is true of some, but not all, single celled organisms living in fresh water.  Some have cell walls, and live under pressure.

Answer 3

b.  Pump water out.  Because the cell has a greater concentration of solutes (like salts, sugars, etc.), water will naturally move from its area of higher concentration (outside) to its area of lower concentration (inside).  If the organism wants to avoid this influx of water, it needs to actively remove it.

Answer 4

No correct answer here. For all such functions cells use membrane transport proteins. Proteins are not organelles by definition.

Fresh water SC organisms must pump water out. And retain salts. And expel some salts (more correctly - ions).