Chapter 50, Problem 1U

Which of the following is NOT an ion homeostatically maintained in vertebrates?

a. Cl^–

b. Na⁺

c. Ca²⁺

d. Fl^–

Summary Introduction

Introduction:

Homeostasis is the regulation of the internal environment of the body at constant level. The overall amount of solute and water that leaves or enters the body must be balanced to maintain the homeostasis.

Answer to Problem 1U

Correct answer:

${\text{Fl}}^{-}$ is NOT an ion homeostatically maintained in vertebrates. Therefore, option d. is correct.

Explanation of Solution

Reason for the correct statement:

The vertebrates maintain homeostasis for concentration of solute present in the extracellular matrix and for the concentration of inorganic ions. The homeostasis of specific inorganic ions such as ${\text{Cl}}^{\text{-}}$, ${\text{Na}}^{\text{+}}$ and ${\text{Ca}}^{\text{2+}}$ is important for the body due to their important functions. So they are maintained at constant levels.

Option d. is given as “ ${\text{Fl}}^{-}$”.

As, “the inorganic ion that is not maintained by vertebrate’s homeostasis is ${\text{Fl}}^{-}$”, is the right answer.

Hence, option d. is correct.

Reasons for the incorrect statements:

Option a. is given as “ ${\text{Cl}}^{\text{-}}$”.

Chloride ion is the major anion present in the extracellular fluid whose concentration is maintained by homeostasis of vertebrates. So, it is a wrong answer.

Option b. is given as “ ${\text{Na}}^{\text{+}}$”.

Sodium ion is the major cation present in extracellular fluid whose concentration is maintained by homeostasis of vertebrates. So, it is a wrong answer.

Option c. is given as “ ${\text{Ca}}^{\text{2+}}$”.

The divalent ion such as calcium has important function and is maintained at constant level (homeostasis) by vertebrates. So, it is a wrong answer.

Hence, options a., b., and c. are incorrect.

Conclusion

Vertebrates do not maintain constant level (homeostasis) of ${\text{Fl}}^{-}$