In the following pictures two organisms are shown On the lef

In the following pictures, two organisms are shown. On the left is a paramecium, which is a unicellular animal that lives in fresh water. On the right is Halobacterium salinarum, which is a species of archaea (a type of prokaryotic organism). Paramecium lives in fresh water, while H. salinarum lives in salt flats where the concentration of the brine can reach over 100 g/mL. In your own words, describe the challenge that each organism faces regarding maintaining the appropriate water content of-their internal environment. What must each of them do successfully to stay alive when it comes to water?

Solution

Paramecium lives in pond (fresh water) so its body is hypertonic compared to the surrounding. Without a osmoregulatory mechanism paramecium would swell and burst as a result of excessive water influx. It regulates water balance by contractile vacuole. As the water moves into the organism by osmosis, the contractile vacuole will swell and burst out water to the surrounding.

Halobacterium salinarum grow in hypersaline environments, to adapt to such extreme environments it concentrates solutes inside their cells to maintain osmotic balance with the external environment. Halobacterium contains a highly concentrated salt solution (KCl), so the osmotic pressure inside and outside the cell is balanced.