Lab 3: The Role of Ions in Nutrition

Fill-in-the-blank practice flashcards covering electrolyte classification, elemental composition, and detection tests for iodide, calcium, phosphate, and iron ions.

Of the 90 naturally occurring elements on Earth, __________ are essential to living organisms.

$$25$$

The four major elements found in all living organisms are carbon, hydrogen, oxygen, and __________.

nitrogen

According to the elemental composition of the human body, oxygen makes up __________ percentage of body mass.

$$65.0\%$$

Solutions containing uncharged particles that do not conduct an electrical current are called __________.

non-electrolytes

The dissolving process shown in the equation $\text{C}_6\text{H}_{12}\text{O}_{6(s)} \rightarrow \text{C}_6\text{H}_{12}\text{O}_{6(aq)}$ represents a __________ solution.

non-electrolyte

Sodium chloride is an example of a __________ electrolyte because it completely dissociates into ions when dissolved in water.

strong

Acetic acid is classified as a weak electrolyte because it undergoes only __________ ionization in water.

$$1\%$$

The hormone responsible for regulating basal metabolic rate, which requires iodide ion for synthesis, is __________.

thyroxine

A deficiency of iodide ion can cause cells of the thyroid gland to enlarge, forming a condition known as a __________.

goiter

The U.S. Recommended Dietary Allowance (RDA) for iodine in adult men and women is __________.

$$0.15\,\text{mg}$$

Recommended Dietary Allowances (RDAs) are established to meet the nutrient requirements of __________ to __________ percent of healthy individuals.

$97\%$ to $98\%$

In the test for iodide ion, iodide is oxidized to free iodine by chlorine water according to the reaction equation __________.

$$2\text{I}^- + \text{Cl}_2 \rightarrow 2\text{Cl}^- + \text{I}_2$$

When iodine is extracted into the non-polar solvent dichloromethane, the dichloromethane layer turns a __________ color.

violet

Adult bone loss caused by the depletion of calcium reserves late in life is known as __________.

osteoporosis

The RDA of calcium for teenagers and young adults aged 11 to 24 is __________.

$$1200\,\text{mg}$$

In the milk test for calcium ion, addition of ammonium oxalate, $(\text{NH}_4)_2\text{C}_2\text{O}_4$, forms a precipitate of __________.

calcium oxalate

Phosphate ions and calcium ions together are essential to the formation of __________ and __________.

bone; tooth

Energy transfer in cells relies on phosphorus compounds in the form of __________.

ATP

Testing milk filtrate for phosphate ion involves adding concentrated nitric acid and ammonium molybdate solution to form a precipitate of __________.

ammonium phosphomolybdate

Oxygen is carried in red blood cells by the protein __________, while oxygen is stored in muscle cells by __________.

hemoglobin; myoglobin

In the U.S., iron-deficiency anemia affects approximately __________ percent of women and __________ percent of men.

$8\%$; $1\%$

The average healthy individual absorbs only about __________ percent of dietary iron.

$$10\%$$

The RDA for iron in pregnant women is __________.

$$30\,\text{mg}$$

In stomach acid, elemental iron is slowly oxidized by hydrochloric acid to the __________ ion.

iron (II)

Reaction of potassium ferricyanide, $\text{K}_3\text{Fe}(\text{CN})_6$, with iron (II) produces a __________ precipitate, whereas reaction with iron (III) produces a __________ precipitate.

dark blue; green

In Part III of the lab procedure, adding acetic acid to milk causes milk fat and __________ protein to precipitate.

casein