Chapter 3 Review Quiz

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. Although van der Waals forces are small, hydrophobic substances form cohesive droplets in aqueous solutions due to:

Ionic bonding between water molecules correct incorrect

Hydrogen bonding between water molecules, forming cages around the nonpolar droplets correct incorrect

Stabilization of the hydrophobic phase by van der Waals interactions between water molecules correct incorrect

The strong van der Waals forces between the nonpolar molecules correct incorrect

Formation of insoluble lipid droplets correct incorrect

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. Molecules tend to diffuse through a semi-permeable membrane:

Only if the molecules are smaller than the holes in the membrane and if their concentration is equal on both sides of the membrane correct incorrect

Only from regions of low concentration to regions of high concentration correct incorrect

From regions of high concentration to regions of low concentration of solute correct incorrect

From regions of high concentration to regions of low concentration only if hydraulic force is applied on both sides intermittently correct incorrect

From regions of low concentration to regions of high concentration only if hydraulic force is applied on the side of high concentration correct incorrect

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. In general, hydrogen bonds:

Are weaker than covalent bonds but stronger than ionic bonds correct incorrect

Occur between polar molecules having hydrogen atoms attached to carbon atoms correct incorrect

Are relatively unimportant, as few ions exist within cells correct incorrect

Are weaker than covalent bonds but stronger than van der Waals forces correct incorrect

Are important in chemistry, but unimportant when considering living things because hydrogen bonds are toxic correct incorrect

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. In COPD (chronic obstructive pulmonary disease), patients are unable to pass carbon dioxide from blood plasma into alveolar air as rapidly as normal. Under these conditions, the patient would probably be:

In acidosis, with a plasma pH above 7.45 correct incorrect

In alkalosis, with a plasma pH below 7.35 correct incorrect

In acidosis, with a plasma pH below 7.35 correct incorrect

In alkalosis, with a plasma pH above 7.45 correct incorrect

Dead; the system could not compensate for this situation correct incorrect

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. Homeostasis maintains a blood plasma pH ranging between 7.35 and 7.45. The kidneys control the amount of bicarbonate ion (which acts as a base in aqueous solution), and the lungs control the amount of carbon dioxide in plasma. If a person suffered acidosis (caused, perhaps, by drinking acid), the body would react by:

The respiratory system would hypoventilate, keeping more CO₂ in the plasma correct incorrect

The lungs would hyperventilate, keeping CO₂ levels high in plasma correct incorrect

The kidneys would remove HCO₃^- from blood plasma and excrete it into the urine correct incorrect

The kidneys would remove CO₂ and excrete it into blood plasma rather than into urine correct incorrect

The lungs would hyperventilate, decreasing CO₂ in the plasma, and the kidneys would save HCO₃^- and excrete it into blood plasma correct incorrect

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. Amphipathic molecules are likely to be found within cell membranes because:

They are soluble in both lipids and aqueous solution and can help stabilize the membrane in contact with the aqueous environment outside the cell correct incorrect

They are especially soluble in lipids such as those present in membranes correct incorrect

Amphipathic molecules are soluble only in aqueous solvents correct incorrect

Membranes are composed of nonpolar molecules such as triacylglycerols and cholesterol correct incorrect

Membranes are self-forming, so amphipathic molecules can form long chains of polymers which can interact with microfilaments and microtubules of the cytoskeleton correct incorrect

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. An artificial kidney uses the process of:

Dialysis across a semipermeable membrane to remove excess quantities of ionic and polar waste materials from blood correct incorrect

Dialysis across a semipermeable membrane to remove excess quantities of nonpolar waste materials from blood correct incorrect

Dialysis across an impermeable membrane to remove excess quantities of polar macromolecular waste materials from blood correct incorrect

Dialysis across an impermeable membrane to remove excess quantities of nonpolar waste materials from blood correct incorrect

Dialysis across a semipermeable membrane to remove excess quantities of protein from blood correct incorrect

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. The pH of blood plasma is maintained between 7.35 and 7.45. Plasma pH can be predicted by using the Henderson/Hasselbalch equation:



The partial pressure of carbon dioxide is controlled by a system which includes sensors in the carotid arteries. When the plasma pH falls during acidosis, this system helps restore pH to normal levels by causing the respiratory system to:

Maintain constant rates of respiration to maintain homeostasis correct incorrect

Hypoventilate correct incorrect

Hyperventilate correct incorrect

Excrete more bicarbonate into the urine correct incorrect

Excrete carbon dioxide into the urine correct incorrect

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. Erythrocytes are considered hypotonic when compared to:

Distilled water correct incorrect

0.9% (w/v) sodium chloride solutions correct incorrect

Syrup correct incorrect

Isotonic saline correct incorrect

Isobars correct incorrect

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. Without knowing the structures of the molecules, you could predict that hydrogen bonds could not form between molecules of:

C₆H₁₂O₆ correct incorrect

CH₃OH correct incorrect

H₂O correct incorrect

CH₄ correct incorrect

C₁₇H₃₅COOH correct incorrect

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. Macromolecules usually have minimal effect on the osmotic environment of a cell because:

They are not soluble correct incorrect

They have no charge on their surfaces correct incorrect

The hydrophobic side chains are turned inward correct incorrect

Although they may make up a large amount of cellular mass, their molar concentrations are small correct incorrect

They are never found within cells and are always negatively charged correct incorrect

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. The most important buffer present in blood plasma is:

HSO₃^-/H₂SO₃ correct incorrect

HPO₄^-2/H₂PO₄^- correct incorrect

Na₂HPO₄/NaH₂PO₄ correct incorrect

HCO₃^-/H₂CO₃ correct incorrect

Na₂CO₃/H₂CO₃ correct incorrect

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. Bones contain a mineral component similar to hydroxyapatite, which sets up an equilibrium in aqueous physiological solution: [Ca₃(PO₄)₂]₃^.Ca(OH)₂ 10 Ca²⁺ + 6 PO₄^3- + 2 OH^- The equilibrium constant for this ionization reaction is 10^-26.4. This would indicate that bone should be:

Relatively soluble under physiological conditions correct incorrect

Soluble only in basic solutions correct incorrect

Soluble in calcium phosphate solutions correct incorrect

Relatively insoluble under physiological conditions correct incorrect

Based on the reaction and the equilibrium constant, it is impossible to predict solubility correct incorrect

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. Acid strength is:

Directly proportional to K_a correct incorrect

Inversely proportional to K_a correct incorrect

Not related to K_a correct incorrect

Equal to 1/K_a correct incorrect

Directly proportional to 1/K_a correct incorrect

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. Consider the equilibrium between ammonia, nitrogen, and hydrogen. 3 H₂ + N₂ ↔ 2 NH₃
If extra hydrogen were added to this system at equilibrium:

Nothing would happen, because the system is already at equilibrium correct incorrect

The concentration of ammonia would decrease correct incorrect

The concentrations of ammonia, hydrogen, and nitrogen would all increase correct incorrect

The equilibrium constant would increase correct incorrect

The concentration of nitrogen would decrease correct incorrect

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. The strength of an acid is:

Directly proportional to the value of the pK_a of the acid correct incorrect

Inversely proportional to pK_a correct incorrect

Not related to pK_a correct incorrect

Equal to 1/pK_a correct incorrect

Directly proportional to 1/K_a correct incorrect

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. In a buffer solution made up of a weak acid and its salt, if the salt concentration is 100 times the concentration of acid, the pH will be:

The same as the pK correct incorrect

One unit below the pK correct incorrect

Two units below the pK correct incorrect

One unit above the pK correct incorrect

Two units above the pk correct incorrect

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. The weakest acid in the following list is:

Carbonic acid correct incorrect

Phosphoric acid correct incorrect

Acetic acid correct incorrect

Hydrochloric acid correct incorrect

Sulfuric acid correct incorrect

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. Given a choice between acid A and acid B,

Acid A is stronger if its conjugate base is stronger than that of Acid B correct incorrect

Acid A is stronger if its conjugate base is weaker than that of Acid B correct incorrect

Acid A is stronger if its conjugate base is a more complex ion than that of Acid B correct incorrect

Acid A is stronger if its conjugate base is a noble gas correct incorrect

There is no way to compare acid strength based on any of these factors correct incorrect

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. A solution having a pH of 5 would have this many times as much hydrogen ion concentration as a solution having a pH of 9:

100 correct incorrect

1000 correct incorrect

10000 correct incorrect

100000 correct incorrect

1000000 correct incorrect

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. Carbon dioxide reacts with water to form carbonic acid which then ionizes according to the following equilibrium reaction: CO₂ +H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃^-
All of the components of the reaction are water soluble, but carbon dioxide is a gas. If you dissolve some sodium bicarbonate in water and then add hydrochloric acid, you should see:

Carbon dioxide bubbling out correct incorrect

Carbon dioxide dissolving correct incorrect

Nothing. Carbon dioxide is an invisible gas correct incorrect

The solution should turn red correct incorrect

The solution should turn blue correct incorrect

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. Hydrophobic molecules are:

Generally nonpolar and relatively insoluble in aqueous solutions correct incorrect

Generally polar and relatively insoluble in aqueous solutions correct incorrect

Generally nonpolar and relatively soluble in aqueous solutions correct incorrect

Generally polar and relatively soluble in aqueous solutions correct incorrect

Neither nonpolar nor soluble in aqueous solutions correct incorrect

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. The mineral component of bone is in equilibrium with a number of ionic substances in aqueous physiological solution: [Ca₃(PO₄)₂]₃^.Ca(OH)₂ ↔ 10 Ca²⁺ + 6 PO₄^3- + 2 OH^- When blood plasma is more acidic than usual, the bone could act as a buffer by:

Providing H₂CO₃ to neutralize excess acid correct incorrect

Providing H₃PO₄ to neutralize excess acid correct incorrect

Dissolving somewhat to release phosphate and hydroxyl ion correct incorrect

Forming more rapidly correct incorrect

Remaining chemically inert correct incorrect