NAS2 Part 4 Review

What is an inorganic compound?

A substance that does not contain both carbon and hydrogen.

What is an organic compound?

A substance that contains both carbon and hydrogen.

What key feature distinguishes organic compounds from inorganic compounds in this section?

Organic compounds contain both carbon and hydrogen; inorganic compounds do not contain both together.

True or false: Every compound that contains carbon is organic.

False. Carbon dioxide (CO₂) contains carbon but is classified as inorganic because it does not contain both carbon and hydrogen.

Why is water (H₂O) classified as inorganic?

It contains hydrogen but no carbon, so it does not contain both carbon and hydrogen.

Why is hydrochloric acid (HCl) classified as inorganic?

It contains hydrogen but no carbon.

Why is carbon dioxide (CO₂) an important exception to the idea that inorganic compounds lack carbon?

CO₂ contains carbon but no hydrogen, so it is still inorganic under the section’s definition.

Which major inorganic compound groups are emphasized as essential to human functioning?

Water, salts, acids, and bases.

How are many organic compounds joined within living organisms?

Their atoms are joined by covalent bonds.

A molecule contains carbon, hydrogen, and oxygen. Based only on the section’s classification rule, is it organic or inorganic?

Organic, because it contains both carbon and hydrogen.

A compound contains carbon and oxygen but no hydrogen. How would this section classify it?

Inorganic, because it does not contain both carbon and hydrogen.

True or false: Inorganic compounds can never contain hydrogen.

False. Water and hydrochloric acid are inorganic compounds that contain hydrogen.

True or false: Inorganic compounds can never contain carbon.

False. A few inorganic compounds, such as carbon dioxide, contain carbon.

Approximately what percentage of an adult’s body weight can be water?

As much as about 70 percent.

Where is body water found?

Inside cells and in the spaces between cells within tissues and organs.

How does water in synovial fluid support joint function?

It lubricates joint movements and reduces friction.

How does water in pleural fluid assist breathing?

It reduces friction as the lungs expand and recoil.

How do watery fluids aid the digestive tract?

They help food move through the tract.

Why can adjacent abdominal organs move with little friction?

Watery fluids lubricate their surfaces.

Give one example of water cushioning the central nervous system.

Water cushions the brain within the skull.

How does water protect the eyes?

It cushions and protects delicate nerve tissue.

How does water protect a developing fetus?

It cushions the fetus in the womb.

What is the difference between water’s lubricating and cushioning roles?

Lubrication reduces friction between moving surfaces; cushioning absorbs or limits physical trauma.

What is a heat sink?

A substance or object that absorbs and dissipates heat without a corresponding large rise in temperature.

Why can water absorb heat produced by body reactions without the body temperature rising sharply?

Water acts as a heat sink and can absorb substantial heat with relatively little temperature change.

Trace the cooling process involving blood flow near the skin.

Warm blood moves from the core to vessels beneath the skin, transfers heat to the environment, and cooler blood returns toward the core.

Trace evaporative cooling from sweating.

Sweat glands release warm water; the water evaporates; evaporation carries heat away from the body.

Why does sweating cool the body most directly?

Evaporation of water removes heat from the skin.

True or false: Water cools the body because sweat becomes colder before it evaporates.

False. Cooling occurs because evaporation carries heat away.

How do peripheral blood flow and sweating work together during heat loss?

Blood brings core heat toward the skin, and evaporation of sweat removes heat from the body surface.

Name four broad roles of water emphasized in the section.

Lubricant and cushion, heat sink, component of liquid mixtures, and participant in chemical reactions.

What is a mixture?

A combination of two or more substances in which each retains its own chemical identity.

How does a mixture differ from a compound?

Mixture components are not chemically bonded into a new substance; a compound contains chemically bonded atoms.

What three types of water-based liquid mixtures are described?

Solutions, colloids, and suspensions.

What is a solution?

A homogeneous liquid mixture in which a solvent dissolves one or more solutes.

What is a solvent?

The liquid component that dissolves another substance.

What is a solute?

A substance dissolved in a solvent.

What does homogeneous mean in describing a solution?

The solute particles are evenly distributed throughout the mixture.

In sugar water, which substance is the solvent and which is the solute?

Water is the solvent; sugar is the solute.

After a sugar solution is stirred thoroughly, how should the sugar-to-water ratio compare on opposite sides of the glass?

It should be the same because the solution is homogeneous.

If more sugar is fully dissolved in the same amount of water, what changes and what stays uniform?

The concentration increases, but the dissolved sugar remains evenly distributed.

Why is water often called the universal solvent?

It dissolves a very wide range of ionic and polar substances and is the body’s most abundant solvent.

Why do most chemical reactions in the body occur in water-based fluids?

Reactants are commonly dissolved in water, allowing them to interact.

Why can polar water molecules dissolve ionic compounds?

Water’s partially positive and negative regions attract and surround oppositely charged ions.

Why can water dissolve many polar covalent compounds?

Water’s charged regions interact with the polar regions of those molecules.

What does hydrophilic mean?

Water-loving; able to interact with and readily dissolve in water.

What does hydrophobic mean?

Water-fearing; nonpolar and not readily soluble in water.

Why is sugar hydrophilic?

Its molecules contain polar hydrogen–oxygen bonds that interact with water.

Compare hydrophilic and hydrophobic substances.

Hydrophilic substances are ionic or polar and dissolve readily in water; hydrophobic substances are nonpolar and do not.

True or false: Every covalent compound dissolves well in water.

False. Polar covalent compounds often dissolve, but nonpolar covalent compounds are generally hydrophobic.

A nonpolar molecule fails to dissolve in body fluid. Which term best describes it?

Hydrophobic.

What is solute concentration?

The number or amount of solute particles in a given volume or space.

What unit is commonly used in the section for blood glucose concentration?

Milligrams per deciliter (mg/dL).

What approximate blood glucose concentration is cited for a healthy adult?

About 100 mg/dL.

What is molarity?

The number of moles of solute per liter of solution.

What does the symbol M represent in a concentration such as 1 M glucose?

Moles per liter, or molarity.

How is a mole of an element related to atomic weight in the section’s calculation framework?

One mole has a mass in grams numerically equal to the element’s atomic weight.

What is molecular weight?

The sum of the atomic weights of all atoms in a compound.

Using C = 12.011 g/mol, what is the carbon contribution to one mole of glucose (C₆H₁₂O₆)?

6 × 12.011 = 72.066 g.

What molecular weight for glucose is calculated in the section?

Approximately 180.156 g per mole.

What does a 1 M glucose solution contain?

One mole of glucose dissolved to make one liter of solution.

What is Avogadro’s number?

6.02 × 10²³ particles per mole.

What feature is the same for one mole of any substance?

The number of particles: 6.02 × 10²³.

What is a millimole (mM in the section’s wording)?

One-thousandth of a mole.

Why are millimoles useful in physiology?

Many solutes in blood and tissues occur in amounts much smaller than a full mole.

How do mg/dL and molarity differ as concentration measurements?

mg/dL expresses mass per volume; molarity expresses moles per liter.

True or false: One mole of glucose and one mole of sodium chloride have the same mass.

False. They contain the same number of particles, but their molecular or formula weights—and therefore masses—differ.

What is a colloid?

A mixture with solute particles present as tiny clumps large enough to scatter light and make the mixture opaque.

Why does a colloid often appear opaque?

Its relatively large particles scatter light.

Name two familiar food examples of colloids.

Milk and cream.

What specialized body example of a colloid is described?

A thick protein mixture in the thyroid gland where thyroid hormone is stored.

What is a suspension?

A liquid mixture in which heavier particles are temporarily dispersed but settle out over time.

What is sedimentation?

The settling of suspended particles out of a liquid.

What does a sedimentation-rate blood test measure?

How quickly red blood cells settle out of plasma over a set time.

What is plasma in the sedimentation-rate example?

The watery portion of blood.

Why may red blood cells settle faster in certain diseases?

They may clump into heavier aggregates that sink more rapidly.

Compare a solution, colloid, and suspension by particle behavior.

Solutions have evenly dispersed molecular or ionic particles; colloids have larger light-scattering particles; suspensions contain heavier particles that eventually settle.

Which liquid mixture is homogeneous: solution, colloid, or suspension?

A solution.

A cloudy mixture remains dispersed because tiny particles scatter light. What type is it?

A colloid.

A mixture separates when left undisturbed. What type is it?

A suspension.

True or false: Sedimentation is expected behavior in a true solution.

False. Sedimentation characterizes a suspension, not a homogeneous solution.

Which two reaction types create or consume water?

Dehydration synthesis and hydrolysis.

What happens during dehydration synthesis?

Reactants form a covalent bond while one supplies H and the other supplies OH; water is released.

What is another name for dehydration synthesis?

A condensation reaction.

Sequence the key events of dehydration synthesis between two monomers.

One monomer loses H, the other loses OH, they form a covalent bond, and H plus OH form water.

Is water a reactant or a product in dehydration synthesis?

A product (byproduct).

What happens during hydrolysis?

Water is split into H and OH and used to break a covalent bond in a compound.

Sequence the key events of hydrolysis.

Water splits into H and OH, the bond between subunits breaks, H attaches to one fragment, and OH attaches to the other.

Is water a reactant or product in hydrolysis?

A reactant.

How are dehydration synthesis and hydrolysis opposites?

Dehydration synthesis joins subunits and releases water; hydrolysis splits a bond and consumes water.

Are dehydration synthesis and hydrolysis reversible?

Yes. They are reverse processes.

In Figure 2.14, what do monomers become when joined by dehydration synthesis?

A polymer, meaning two or more chemically bonded monomers.

In Figure 2.14, what visual clue identifies dehydration synthesis?

Two monomers join while a water molecule is released.

In Figure 2.14, what visual clue identifies hydrolysis?

Water is added as the bond between monomers is split.

True or false: Hydrolysis releases water when it breaks a polymer.

False. Hydrolysis requires the addition and splitting of water.

A reaction joins two small molecules and produces H₂O. Which process occurred?

Dehydration synthesis (condensation).

A covalent bond is broken after H₂O is added. Which process occurred?

Hydrolysis.

What is a salt?

A substance that dissociates in water into ions other than H⁺ or OH⁻.

How are salts formed at the atomic level?

Oppositely charged ions form ionic bonds after electrons are transferred.

What happens to sodium chloride when it dissolves in water?

It dissociates completely into Na⁺ and Cl⁻ ions.