(S)-Zearalenone, a natural product isolated from the fungus Gibberella zeae, exhibits useful biological activity, including antibiotic properties. In a total synthesis of (S)-zearalenone, an intramolecular Stille coupling process was employed as the penultimate procedure.3 The resulting coupling product was then treated with HCl to cleave the OR groups, thereby converting them into OH groups (as seen in Section 13.6), giving (S)-zearalenone. Draw the structure of (S)-zearalenone:

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.