Target Exam

CUET

Subject

Biology

Chapter

Organisms and Populations

Question:

The organisms that are tolerant to wide range of salinity, are called:

Options:

Euryhaline

Stenohaline

Eurythermal

Stenothermal

Correct Answer:

Euryhaline

Explanation:

The correct answer is Option (1) → Euryhaline

Water is the most important factor influencing the life of organisms. Its availability is so limited in deserts that only special adaptations make it possible to live there. The productivity and distribution of plants is also heavily dependent on water. For aquatic organisms the quality (chemical composition, pH) of water becomes important. The salt concentration (measured as salinity in parts per thousand), is less than 5 in inland waters, 30-35 in the sea and > 100 in some hypersaline lagoons. Some organisms are tolerant of a wide range of salinities (euryhaline) but others are restricted to a narrow range (stenohaline). Many freshwater animals cannot live for long in sea water and vice versa because of the osmotic problems, they would face.

A few organisms can tolerate and thrive in a wide range of temperatures (they are called eurythermal), but, a vast majority of them are restricted to a narrow range of temperatures (such organisms are called stenothermal ). The levels of thermal tolerance of different species determine to a large extent their geographical distribution.