1. is a component of bone and is required for metabolic reactions. 2. contributes to growth of bones, teeth, and connective tissue and is needed for the immune system. contributes to growth of bones, teeth, and connective tissue and is needed for the immune system. 3. is needed for proper thyroid function. is needed for proper thyroid function. 4. is the most prevalent positive ion in fluids outside cells and is needed for water balance, muscle contraction, and nerve impulses. is the most prevalent positive ion in fluids outside cells and is needed for water balance, muscle contraction, and nerve impulses. 5. is a component of vitamin B12 and red blood cells is a component of vitamin B12 and red blood cells

1. Calcium

2. Calcium

3. Iodine

4. Sodium

5. Cobalt

Explanation:

Calcium is an essential nutrient which provide rigidity to skeleton by virtue of insoluble salts it form with phosphoric acid hydroxyapatite. It plays important role in muscle contraction, hormone release, nerve conduction, blood coagulation, bone and teeth growth and metabolic process like enzymatic reactions.

Iodine is important in the normal functioning of the thyroid gland, it is required for the synthesis of thyroxine (T4) and tri-iodothyronine (T3) which affect many metabolic processes.

Sodium is the most abundant positive ion, there are approximately 3000mmol of sodium in extracellular fluid. It account for the osmotic activity of the extracellular fluid compartment. It is also an important in the development of action potential for muscle and nerve conduction.

Cobalt is and important component of both vitamin B12 (cyanocobalamin) and red blood cells.