why might some kinds of living things undergo sexual reproduction at times when conditions in their environment become less favorable?

The ANSWER is:

Assuming ur doing SOS:

In organisms that most often reproduce asexually, the product of sexual reproduction is often more resistant to unfavorable environmental conditions than the individual of the species produced by mitosis. Some kinds of protists such as protozoans and algae do not usually reproduce sexually unless growing conditions have become unfavorable. Many plants do not produce seeds until the approach of winter or a dry period of the year.

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.