Question

Many fresh water animals cannot live for long in sea water and vice versa mainly because;
A) Change in nitrogen level
B) Change in thermal tolerance
C) Variation in light intensity
D) Osmotic problems

Answer 1

Hint: The water in the sea water is saline and thus hypertonic to the cells of the body that contributes to exosmosis.

Complete answer:
- In sea water, the salinity, or the salt level, is much greater, but fresh water is not completely free of salt. Sea water consists of different elements, and when they break down, they form ions that are electrically charged. Good electricity conductors are these particles. This suggests that energy flows more easily and effectively via sea water than it does from fresh water.
- The biological differences are interesting. In all forms of water, fish, amphibians, and plants usually do not survive. Their normal growth lends them to their preferred amount of salt content. It is about as productive to take a fresh water fish and place him in a seawater tank as leaving him on the shore.
- He apparently can't be able to survive. However, there are alligators who have adapted to the environment of freshwater and seawater.

Now, let us find the solution from the options-
- A fish is hypertonic to its environment in freshwater, meaning fish is saltier and water flows continuously through Osmosis through the fish body.
- When freshwater fish are put in sea water, in contrast to the environment, freshwater fish are hypotonic or less salty. This suggests that water constantly flows out of the body of the fish which contributes to the fish’s demise. Therefore, many freshwater species do not remain in sea water for long and vice versa, largely due to osmotic issues. Thus, the option A. B and C are incorrect.

Thus, the correct answer is option (D) Osmotic problems.

Note: In sea water, the explanation why freshwater fish do not live and vice versa does have a lot to do with a principle called tonicity of any liquid. It is the capacity of a solution, in simple words, to exert osmotic pressure on a membrane. There are three types of tonicity: hypertonic, hypotonic, and isotonic.