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Chapter 2 Flashcards

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1
Q

Which of the following properties of water is directly responsible for its high boiling point and surface tension?

A) High molecular weight
B) Strong covalent bonds
C) Hydrogen bonding
D) Van der Waals forces

A

C) Hydrogen bonding
Water has a high boiling point and surface tension because of the strong hydrogen bonds between water molecules. These bonds require a significant amount of energy to break, leading to the anomalously high boiling point and surface tension.

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2
Q

What is the significance of the difference in hydrogen ion concentration across a biological membrane?

A) It determines the pH of the cell.
B) It is essential for the maintenance of cell volume.
C) It drives the synthesis of ATP through chemiosmosis.
D) It causes membrane depolarization.

A

C) It drives the synthesis of ATP through chemiosmosis
The difference in hydrogen ion concentration (proton gradient) across a membrane is a critical aspect of energy transformation in cells. This gradient is used to synthesize ATP, the primary energy currency of the cell, through a process called chemiosmosis.

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3
Q

Which statement best explains the importance of hydroxide ions (OH⁻) in biological systems?

A) They stabilize the tertiary structure of proteins.
B) They are involved in the ionization of weak acids and bases.
C) They are a primary source of energy for cellular processes.
D) They help maintain the electrical neutrality of the cell.

A

B) They are involved in the ionization of weak acids and bases
Hydroxide ions play a key role in the ionization of weak acids and bases, which is crucial in maintaining the proper pH balance in biological systems. This ionization is important for enzyme activity, protein structure, and other cellular processes.

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4
Q

Why is the surface tension of water important in biological systems?

A) It allows for the formation of hydrogen bonds in biomolecules.
B) It facilitates the capillary action necessary for water transport in plants.
C) It decreases the energy required for cellular processes.
D) It increases the solubility of gases in water.

A

B) It facilitates the capillary action necessary for water transport in plants
The high surface tension of water is critical for capillary action, which is essential for the transport of water (and nutrients dissolved in it) from roots to leaves in plants. This is vital for plant physiology.

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5
Q

Which of the following statements about water is incorrect?

A) Water’s high heat of vaporization is due to strong intermolecular forces.
B) Water ionizes to form H⁺ and OH⁻ ions, critical for biomolecular function.
C) Water’s low molecular weight contributes to its high boiling point.
D) Water has anomalously high physical properties compared to other molecules of similar size.

A

C) Water’s low molecular weight contributes to its high boiling point
This statement is incorrect because water’s high boiling point is due to hydrogen bonding, not its molecular weight. Water actually has a relatively low molecular weight, yet it has a high boiling point due to the strong intermolecular hydrogen bonds.

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6
Q

Which of the following best explains why ice floats on water?

A) Water has a higher boiling point than most liquids.
B) Water’s solid form (ice) is less dense than its liquid form.
C) Ice is held together by strong covalent bonds that repel water molecules.
D) Ice forms a crystalline structure that traps air bubbles, making it buoyant.

A

B) Water’s solid form (ice) is less dense than its liquid form.

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7
Q

Why does water have such anomalously high boiling and melting points compared to other substances of similar molecular weight?

A) Water has a high molecular weight.
B) Water molecules are held together by strong hydrogen bonds.
C) Water has a strong metallic bond.
D) Water has weak van der Waals forces.

A

B) Water molecules are held together by strong hydrogen bonds.

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8
Q

What causes the permanent dipole in a water molecule?

A) The similar electronegativities of oxygen and hydrogen.
B) The unequal sharing of electrons between oxygen and hydrogen atoms.
C) The symmetrical shape of the water molecule.
D) The presence of ionic bonds within the water molecule.

A

B) The unequal sharing of electrons between oxygen and hydrogen atoms.

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8
Q

What is the primary reason for the negative volume of melting in water?

A) Water molecules become more tightly packed when they freeze.
B) Ice has a higher density than liquid water.
C) Ice occupies more space due to the hydrogen-bonded crystalline structure.
D) The dipole-dipole interactions in water increase as it freezes

A

C) Ice occupies more space due to the hydrogen-bonded crystalline structure.

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9
Q

Which of the following statements about water’s solvent properties is true?

A) Water is a non-polar solvent, dissolving non-polar substances easily.
B) Water’s ability to dissolve many substances is due to its polar nature.
C) Water cannot dissolve ionic compounds.
D) Water dissolves substances by breaking covalent bonds.

A

B) Water’s ability to dissolve many substances is due to its polar nature.

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10
Q

What does it mean when we say that hydrogen bonding in water is “cooperative”?

A) Water molecules can only donate hydrogen bonds, not accept them.
B) A water molecule that donates a hydrogen bond becomes a better hydrogen bond acceptor.
C) Water molecules form hydrogen bonds only when no other molecules are present.
D) Hydrogen bonds between water molecules are weak and easily broken.

A

B) A water molecule that donates a hydrogen bond becomes a better hydrogen bond acceptor.

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10
Q

The high surface tension of water is primarily due to:

A) Van der Waals forces between water molecules.
B) Hydrogen bonding between water molecules.
C) The ionic nature of water.
D) Water’s ability to form covalent bonds

A

B) Hydrogen bonding between water molecules.

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11
Q

How does the hydrogen bonding in water differ when comparing its liquid and solid states?

A) Hydrogen bonds are stronger in the liquid state, allowing more compact molecule arrangement.
B) Hydrogen bonds in the solid state (ice) form a rigid, open lattice, spacing molecules further apart.
C) Hydrogen bonds are absent in the solid state, making ice denser than water.
D) Hydrogen bonding only occurs in the liquid state, not in the solid state

A

B) Hydrogen bonds in the solid state (ice) form a rigid, open lattice, spacing molecules further apart.

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11
Q

How does hydrogen bonding contribute to the structure of ice?

A) Hydrogen bonds cause water molecules to be closer together in ice than in liquid water.
B) Hydrogen bonds in ice form a lattice structure that spaces water molecules farther apart than in liquid water.
C) The hydrogen bonds in ice are weaker than in liquid water, allowing molecules to move freely.
D) Hydrogen bonds do not play a significant role in the structure of ice.

A

B) Hydrogen bonds in ice form a lattice structure that spaces water molecules farther apart than in liquid water.

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12
Q

Which of the following is a direct consequence of water’s polar nature?

A) Water has a high boiling point relative to its molecular weight.
B) Water is a poor solvent for ionic compounds.
C) Water molecules cannot form hydrogen bonds with each other.
D) Water easily dissolves non-polar substances.

A

A) Water has a high boiling point relative to its molecular weight

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13
Q

What makes water an excellent solvent for ionic and polar compounds?

A) Its non-polar nature allows it to dissolve a wide range of substances.
B) The cooperative hydrogen bonding in water repels non-polar substances.
C) The high polarity of water enables it to interact strongly with ionic and polar compounds, dissolving them.
D) Water’s low density makes it an excellent solvent.

A

C) The high polarity of water enables it to interact strongly with ionic and polar compounds, dissolving them.

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14
Q

In what way does the cooperative nature of hydrogen bonding in water influence its solvent properties?

A) It makes water unable to dissolve ionic compounds.
B) It enhances water’s ability to break down and dissolve substances by maintaining strong bonds between its molecules.
C) It prevents water from forming hydrogen bonds with solute molecules.
D) It reduces water’s effectiveness as a solvent for polar substances.

A

B) It enhances water’s ability to break down and dissolve substances by maintaining strong bonds between its molecules.

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15
Q

What is the primary driving force behind hydrophobic interactions in water?

A) The attraction between nonpolar molecules and water molecules.
B) The tendency of nonpolar molecules to increase entropy when dispersed in water.
C) The reorganization of water’s hydrogen-bonded network to minimize contact with nonpolar molecules.
D) The formation of hydrogen bonds between nonpolar molecules

A

C) The reorganization of water’s hydrogen-bonded network to minimize contact with nonpolar molecules.

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15
Q

How does water’s high dielectric constant influence its ability to dissolve ionic compounds?

A) It reduces the electrostatic attraction between oppositely charged ions, allowing them to dissociate.
B) It increases the attraction between ions, making them harder to dissolve.
C) It has no effect on the dissolution of ionic compounds.
D) It causes ionic compounds to precipitate out of solution.

A

A) It reduces the electrostatic attraction between oppositely charged ions, allowing them to dissociate.

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16
Q

Why is water considered an excellent solvent for polar solutes?

A) It forms strong covalent bonds with polar solutes.
B) It readily forms hydrogen bonds with the polar functional groups on these solutes.
C) It forms clathrate structures around polar solutes.
D) It dissolves polar solutes by breaking their covalent bonds.

A

B) It readily forms hydrogen bonds with the polar functional groups on these solutes.

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17
Q

What happens to water molecules when nonpolar solutes are introduced into the solution?

A) Water molecules form hydrogen bonds with the nonpolar solutes.
B) Water molecules remain disorganized and do not interact with the nonpolar solutes.
C) Water molecules reorganize into a clathrate structure around the nonpolar solutes.
D) Water molecules completely ignore the presence of nonpolar solutes.

A

C) Water molecules reorganize into a clathrate structure around the nonpolar solutes.

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18
Q

Which of the following is not a colligative property?

A) Freezing point depression
B) Boiling point elevation
C) Vapor pressure lowering
D) Density of the solvent

A

D) Density of the solvent

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18
Q

What happens to the freezing point of a solution when a non-volatile solute is added?

A) It increases
B) It decreases
C) It remains the same
D) It fluctuates based on the solute concentration

A

B) It decreases

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19
Q

Why does the boiling point of a solution increase when a solute is dissolved in it?

A) The solvent’s vapor pressure is increased.
B) The solution forms hydrogen bonds more easily.
C) The solvent’s vapor pressure is lowered.
D) The solution’s density increases.

A

C) The solvent’s vapor pressure is lowered.

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20
Q

What is the effect of adding a non-volatile solute to a solvent on the vapor pressure of the solvent?

A) The vapor pressure increases.
B) The vapor pressure decreases.
C) The vapor pressure remains unchanged.
D) The vapor pressure initially decreases and then increases.

A

B) The vapor pressure decreases.

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21
Q

Which of the following statements best explains why salt is added to ice in an ice-cream maker?

A) To increase the ice’s melting point
B) To decrease the freezing point of water in the ice, leading to more efficient cooling
C) To make the ice more solid
D) To lower the boiling point of water in the ice

A

B) To decrease the freezing point of water in the ice, leading to more efficient cooling

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21
Q

Osmotic pressure is directly related to:

A) The number of solute particles in the solution
B) The mass of the solute
C) The boiling point of the solvent
D) The type of solute particles

A

A) The number of solute particles in the solution

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22
Q

What is osmotic pressure?

A) The pressure required to stop the flow of solvent into a solution through a semipermeable membrane
B) The pressure needed to vaporize a solvent
C) The pressure that builds up due to the presence of solute molecules
D) The pressure needed to freeze a solution

A

A) The pressure required to stop the flow of solvent into a solution through a semipermeable membrane

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22
Q

Which colligative property is responsible for making it more difficult for water to escape into the atmosphere when a solute is added?

A) Freezing point depression
B) Boiling point elevation
C) Vapor pressure lowering
D) Osmotic pressure

A

C) Vapor pressure lowering

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23
Q

Why do cells store substances like amino acids and sugars in polymeric form to minimize osmotic pressure?

A) Polymers occupy less space in the cell.
B) Polymers exert less osmotic pressure than their monomeric forms.
C) Polymers are more reactive and help speed up cellular processes.
D) Polymers help maintain the cell’s structure

A

B) Polymers exert less osmotic pressure than their monomeric forms.

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23
Q

When a weak acid like HF is dissolved in water, how does the reaction proceed to equilibrium?

A) The forward reaction continuously speeds up until equilibrium is reached.
B) The reverse reaction speeds up as the concentration of products increases.
C) The rate of the forward reaction remains constant.
D) The reaction goes to completion without reaching equilibrium.

A

B) The reverse reaction speeds up as the concentration of products increases.

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24
Q

What would happen to a cell if it stored all of its glucose in monomeric form rather than as a polymer like glycogen?

A) The cell would experience lower osmotic pressure.
B) The cell would maintain the same osmotic pressure.
C) The cell would experience higher osmotic pressure, leading to possible lysis.
D) The cell’s osmotic pressure would decrease, causing it to shrivel.

A

C) The cell would experience higher osmotic pressure, leading to possible lysis.

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24
Q

At equilibrium in the dissociation of HF in water, what is true about the rates of the forward and reverse reactions?

A) The forward reaction rate is greater than the reverse reaction rate.
B) The reverse reaction rate is greater than the forward reaction rate.
C) The forward and reverse reaction rates are equal.
D) Both reaction rates are zero.

A

C) The forward and reverse reaction rates are equal.

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25
Q

How does the presence of solute molecules affect osmotic pressure?

A) It decreases osmotic pressure.
B) It increases osmotic pressure.
C) It has no effect on osmotic pressure.
D) It increases the rate of solvent diffusion through the membrane.

A

B) It increases osmotic pressure.

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26
Q

Which of the following is true as a weak acid reaction (e.g., HF in water) approaches equilibrium?

A) The concentration of HF increases continuously.
B) The concentrations of F⁻ and H₃O⁺ decrease until equilibrium is reached.
C) The rate of formation of HF increases as the concentrations of F⁻ and H₃O⁺ increase.
D) The concentrations of HF, F⁻, and H₃O⁺ remain constant before equilibrium is reached.

A

C) The rate of formation of HF increases as the concentrations of F⁻ and H₃O⁺ increase.

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26
Q

Before equilibrium is reached, the concentrations of the reactants and products?

A

Reactants and product

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27
Q

initially, reactants have a ______ rate of reaction than the rate of reaction of the product

A

Higher

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28
Q

At equilibrium, the rate of the forward reaction is_________ to the rate of the reverse reaction

A

Equal

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29
Q

According to Le Châtelier’s Principle, what happens when the concentration of a reactant in a system at equilibrium is increased?

A) The equilibrium shifts to produce more reactants.
B) The equilibrium shifts to produce more products.
C) The equilibrium remains unchanged.
D) The equilibrium shifts to reduce the concentration of the reactant.

A

B) The equilibrium shifts to produce more products.

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30
Q

What happens to the rates of the forward and reverse reactions when a stress is applied to a system at equilibrium?

A) The rate of the forward reaction increases, and the rate of the reverse reaction decreases.
B) The rates of both reactions remain the same.
C) The rates of the forward and reverse reactions change to reestablish equilibrium.
D) The rate of the reverse reaction increases, and the rate of the forward reaction decreases.

A

C) The rates of the forward and reverse reactions change to reestablish equilibrium.

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31
Q

In the lungs, where the concentration of oxygen (O₂) is high, which direction does the hemoglobin (Hb) and oxygen (O₂) equilibrium shift?

A) Toward the formation of hemoglobin (Hb)
B) Toward the formation of oxyhemoglobin (HbO₂)
C) The equilibrium does not shift.
D) Toward the release of oxygen from hemoglobin

A

B) Toward the formation of oxyhemoglobin (HbO₂)

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32
Q

What happens to the oxygen-hemoglobin equilibrium in tissues where the concentration of oxygen (O₂) is low?

A) The equilibrium shifts to produce more oxyhemoglobin (HbO₂).
B) The equilibrium shifts to release oxygen from hemoglobin.
C) The equilibrium remains unchanged.
D) The equilibrium shifts to increase the concentration of oxygen in the tissues.

A

B) The equilibrium shifts to release oxygen from hemoglobin.

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33
Q

At high altitudes, where oxygen levels are lower, what is a likely physiological response according to the oxygen-hemoglobin equilibrium?

A) The body produces less hemoglobin to conserve oxygen.
B) The equilibrium shifts toward the formation of oxyhemoglobin (HbO₂).
C) The equilibrium shifts toward the release of oxygen from hemoglobin.
D) The equilibrium remains the same, but the oxygen-hemoglobin binding strength increases.

A

C) The equilibrium shifts toward the release of oxygen from hemoglobin.

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34
Q

Which of the following is NOT a symptom of hypoxia experienced at high altitudes?

A) Increased respiratory rate
B) Headache
C) Decreased red blood cell production
D) Decreased physical coordination

A

D) Decreased physical coordination

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35
Q

How does the body adapt to lower oxygen levels at high altitudes over time?

A) By decreasing hemoglobin levels
B) By decreasing red blood cell count
C) By increasing red blood cell production
D) By producing more oxygen

A

C) By increasing red blood cell production

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36
Q

If the concentration of a product is increased in a system at equilibrium, what does Le Châtelier’s Principle predict will happen?

A) The equilibrium will shift to the right, forming more products.
B) The equilibrium will shift to the left, forming more reactants.
C) The equilibrium will remain unchanged.
D) The system will create new reactants and products equally.

A

B) The equilibrium will shift to the left, forming more reactants.

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37
Q

What is the pH of a neutral aqueous solution at 25°C?

A) 0
B) 7
C) 10
D) 14

A

B) 7

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38
Q

If the pH of a solution is 4, what is the pOH of the solution at 25°C?

A) 4
B) 7
C) 10
D) 14

A

C) 10

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39
Q

Which of the following is NOT a characteristic of an acid according to the Arrhenius definition?

A) Sour taste
B) Turns blue litmus red
C) Reacts with carbonates to produce CO₂
D) Turns red litmus blue

A

D) Turns red litmus blue

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40
Q

Which of the following is a property of a base according to the Arrhenius definition?

A) Sour taste
B) Reacts with metals to produce hydrogen gas
C) Turns red litmus blue
D) Produces CO₂ when reacting with carbonates

A

C) Turns red litmus blue

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41
Q

According to the Arrhenius definition, which of the following compounds is classified as a base?

A) HCl
B) NaOH
C) CH₃COOH
D) NH₃

A

B) NaOH The Arrhenius definition of a base is a substance that dissociates in water to produce hydroxide ions (OH⁻).

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42
Q

Which of the following correctly describes a Brønsted-Lowry acid?

A) A substance that accepts a proton
B) A substance that donates a proton
C) A substance that dissociates to form OH⁻ ions
D) A substance that reacts with fats to form soaps

A

B) A substance that donates a proton

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42
Q

What is the product of the reaction between an acid and a base?

A) Hydrogen gas and a salt
B) Water and carbon dioxide
C) A salt and water
D) A salt and carbon dioxide

A

C) A salt and water

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43
Q

Which of the following acids would be correctly classified under both the Arrhenius and Brønsted-Lowry definitions?

A) H₂O
B) NH₃
C) HCl
D) NaOH

A

C) HCl

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44
Q

Which of the following is a characteristic reaction of acids with carbonates?

A) Production of hydrogen gas
B) Formation of a precipitate
C) Release of carbon dioxide gas
D) Formation of soap

A

C) Release of carbon dioxide gas

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44
Q

Which reaction best illustrates the Brønsted-Lowry concept of acid-base behavior?

A) NaOH → Na⁺ + OH⁻
B) HCl + H₂O → H₃O⁺ + Cl⁻
C) H₂O + CO₂ → H₂CO₃
D) NaCl → Na⁺ + Cl⁻

A

B) HCl + H₂O → H₃O⁺ + Cl⁻

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45
Q

Which of the following is a common property of bases?

A) Sour taste
B) Bitter taste
C) Reacts with carbonates to produce CO₂
D) Turns blue litmus red

A

B) Bitter taste

46
Q

In the reaction HCl (aq) + H₂O (l) → Cl⁻ (aq) + H₃O⁺ (aq), which species acts as the Brønsted-Lowry acid?

A) HCl
B) H₂O
C) Cl⁻
D) H₃O⁺

A

A) HCl

47
Q

In the reaction HCl (aq) + H₂O (l) → Cl⁻ (aq) + H₃O⁺ (aq), which species acts as the Brønsted-Lowry base?

A) HCl
B) H₂O
C) Cl⁻
D) H₃O⁺

A

B) H₂O

47
Q

Which statement best describes the Brønsted-Lowry theory of acids and bases?

A) Acids and bases can only exist in aqueous solutions.
B) An acid donates a proton, while a base accepts a proton.
C) Acids dissociate in water to produce H⁺ ions, and bases produce OH⁻ ions.
D) Bases can only neutralize acids in water.

A

B) An acid donates a proton, while a base accepts a proton.

48
Q

Which of the following is an example of a Brønsted-Lowry acid-base reaction that does not occur in water?

A) NH₃ + HCl → NH₄Cl
B) HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)
C) H₂SO₄ + H₂O → HSO₄⁻ + H₃O⁺
D) NaOH (aq) → Na⁺ (aq) + OH⁻ (aq)

A

A) NH₃ + HCl → NH₄Cl

49
Q

Which of the following statements distinguishes the Brønsted-Lowry theory from the Arrhenius theory?

A) Brønsted-Lowry theory is only applicable in aqueous solutions.
B) Brønsted-Lowry theory considers acids and bases only as ionic compounds.
C) Brønsted-Lowry theory includes acid-base reactions in non-aqueous solutions.
D) Brønsted-Lowry theory is only applicable to organic compounds.

A

C) Brønsted-Lowry theory includes acid-base reactions in non-aqueous solutions.

50
Q

Which of the following reactions demonstrates the Brønsted-Lowry theory in a non-aqueous environment?

A) HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)
B) H₂SO₄ + H₂O → HSO₄⁻ + H₃O⁺
C) HCl (g) + NH₃ (g) → NH₄Cl (s)
D) NaOH (s) → Na⁺ (aq) + OH⁻ (aq)

A

C) HCl (g) + NH₃ (g) → NH₄Cl (s)

51
Q

In a Brønsted-Lowry acid-base reaction, what occurs during the proton transfer?

A) The base donates a proton to the acid.
B) The acid donates a proton to the base.
C) The acid and base exchange electrons.
D) The base accepts an electron pair from the acid.

A

B) The acid donates a proton to the base.

51
Q

In the reaction HCl (aq) + H₂O (l) → Cl⁻ (aq) + H₃O⁺ (aq), which of the following pairs represents a conjugate acid-base pair?

A) HCl and H₂O
B) HCl and Cl⁻
C) H₂O and H₃O⁺
D) Cl⁻ and H₃O⁺

A

B) HCl and Cl⁻

52
Q

Why is the Brønsted-Lowry definition of acids and bases considered an improvement over the Arrhenius definition?

A) It only applies to aqueous solutions.
B) It includes acid-base reactions in the gas phase and non-aqueous solutions.
C) It limits the types of compounds that can be classified as acids or bases.
D) It simplifies the understanding of acid-base chemistry.

A

B) It includes acid-base reactions in the gas phase and non-aqueous solutions.

53
Q

How does the choice of solvent affect the classification of acids and bases according to the Brønsted-Lowry definition?

A) Acids and bases only exist in water.
B) Acids and bases cannot exist in non-polar solvents.
C) The solvent can change which substances act as acids or bases.
D) The solvent has no effect on acid-base behavior.

A

C) The solvent can change which substances act as acids or bases.

54
Q

Label the acid, base, conjugate acid, and conjugate base in each reaction

HCl + OH- → Cl ̶ + H2O

A

HCl: Acid (donates a proton to OH⁻)
OH⁻: Base (accepts a proton from HCl)
Cl⁻: Conjugate base (formed after HCl donates a proton)
H₂O: Conjugate acid (formed after OH⁻ accepts a proton)

55
Q

Label the acid, base, conjugate acid, and conjugate base in each reaction

H2O + H2SO4 → HSO4
̶ + H3O

A

H₂SO₄: Acid (donates a proton to H₂O)
H₂O: Base (accepts a proton from H₂SO₄)
HSO₄⁻: Conjugate base (formed after H₂SO₄ donates a proton)
H₃O⁺: Conjugate acid (formed after H₂O accepts a proton)

56
Q

Which of the following statements is true regarding the reaction of HCl with H₂O?

A) The equilibrium lies far to the left, favoring the reactants.
B) The equilibrium lies far to the right, favoring the products.
C) The reaction is reversible, but HCl does not dissociate completely.
D) HCl behaves as a Brønsted-Lowry base.

A

B) The equilibrium lies far to the right, favoring the products.

Explanation:
The dissociation of HCl in water is a strong acid reaction, meaning it almost completely dissociates into H⁺ and Cl⁻ ions. This indicates that the equilibrium lies far to the right, favoring the products.

57
Q

In the reaction of HCl with H₂O, which species acts as the Brønsted-Lowry acid?

A) H₂O
B) Cl⁻
C) H₃O⁺
D) HCl

A

D) HCl

58
Q

What type of arrows are used to represent the ionization of weak acids?

A) A single arrow pointing to the right
B) A double arrow
C) A single arrow pointing to the left
D) No arrows, as weak acids do not ionize

A

B) A double arrow

58
Q

Which of the following is the conjugate base of HCl?

A) H₂O
B) Cl⁻
C) H₃O⁺
D) OH⁻

A

B) Cl⁻

59
Q

Which of the following statements about strong acids is correct?

A) Strong acids never fully dissociate, even in dilute solutions.
B) Strong acids ionize partially in water.
C) Strong acids are 100% dissociated in solutions of 1.0 M or less.
D) Strong acids are weak at high concentrations.

A

C) Strong acids are 100% dissociated in solutions of 1.0 M or less.

59
Q

Which of the following statements best describes a conjugate acid-base pair?

A) They are always found in different chemical reactions.
B) They differ by one neutron in their formulas.
C) They differ by one proton in their formulas.
D) They always contain strong acids and strong bases.

A

C) They differ by one proton in their formulas.

60
Q

If HF is a weak acid, what can be inferred about its ionization in water?

A) It ionizes completely, similar to HCl.
B) It ionizes partially and establishes an equilibrium.
C) It does not ionize at all.
D) It forms a strong base upon ionization.

A

B) It ionizes partially and establishes an equilibrium.

60
Q

The six common strong acids are:

A

Hydrochloric Acid (HCl)
Hydrobromic Acid (HBr)
Hydroiodic Acid (HI)
Sulfuric Acid (H₂SO₄) (only the first dissociation is strong)
Nitric Acid (HNO₃)
Perchloric Acid (HClO₄)

61
Q

The six common strong bases are:

A

Sodium Hydroxide (NaOH)
Potassium Hydroxide (KOH)
Lithium Hydroxide (LiOH)
Calcium Hydroxide (Ca(OH)₂)
Barium Hydroxide (Ba(OH)₂)
Strontium Hydroxide (Sr(OH)₂)

62
Q

What is the main function of buffers in biological systems?

A) To increase the pH of body fluids.
B) To prevent large fluctuations in pH.
C) To decrease the pH of body fluids.
D) To neutralize strong acids and bases.

A

B) To prevent large fluctuations in pH.

63
Q

Which organs are primarily responsible for regulating the pH of body fluids?

A) Liver and pancreas
B) Heart and lungs
C) Lungs and kidneys
D) Stomach and intestines

A

C) Lungs and kidneys

63
Q

Which of the following best describes a buffer solution?

A) A solution that neutralizes any added acid.
B) A solution that neutralizes any added base.
C) A solution containing an acid-base conjugate pair that resists changes in pH.
D) A solution that contains only a strong acid or a strong base.

A

C) A solution containing an acid-base conjugate pair that resists changes in pH.

63
Q

What distinguishes a strong acid from a weak acid?

A) Strong acids have more hydrogen atoms than weak acids.
B) Strong acids completely dissociate in water, while weak acids do not.
C) Weak acids have a higher pH than strong acids.
D) Weak acids are found in biological systems, while strong acids are not.

A

B) Strong acids completely dissociate in water, while weak acids do not.

64
Q

Which of the following is a characteristic of a weak acid?

A) It completely dissociates in water.
B) It dissociates poorly in water, releasing few protons.
C) It cannot participate in buffer solutions.
D) It has no conjugate base.

A

B) It dissociates poorly in water, releasing few protons.

65
Q

Why are weak acids commonly used in buffer solutions?

A) Because they completely dissociate, allowing the buffer to absorb more acid.
B) Because they can donate protons and accept them back, maintaining equilibrium.
C) Because they neutralize strong bases immediately.
D) Because they have a higher pH than strong acids.

A

B) Because they can donate protons and accept them back, maintaining equilibrium.

66
Q

Which of the following is the primary function of a buffer in a biological system?
A) To completely neutralize all acids and bases
B) To prevent large fluctuations in pH
C) To increase the pH of the solution
D) To decrease the pH of the solution

A

B) To prevent large fluctuations in pH

67
Q

In the bicarbonate buffer system (H₂CO₃/HCO₃⁻), what happens when a small amount of acid is added to the blood? A) The pH increases significantly.
B) The pH decreases slightly.
C) The HCO₃⁻ reacts with the acid to form H₂CO₃.
D) The H₂CO₃ dissociates into CO₂ and H₂O.

A

C) The HCO₃⁻ reacts with the acid to form H₂CO₃.

67
Q

Which of the following pairs correctly represents a buffer system?
A) HCl/Cl⁻
B) NaOH/Na⁺
C) CH₃COOH/CH₃COO⁻
D) H₂O/H⁺

A

C) CH₃COOH/CH₃COO⁻

68
Q

What is the effect of adding a strong base to an ammonia buffer system (NH₃/NH₄⁺)?
A) The pH increases drastically.
B) The NH₄⁺ reacts with OH⁻ to form NH₃ and water.
C) The NH₃ concentration decreases.
D) The buffer system is destroyed.

A

B) The NH₄⁺ reacts with OH⁻ to form NH₃ and water.

68
Q

Which of the following statements is true about the phosphate buffer system? A) It is primarily used in extracellular fluid.
B) It works best at a pH close to 7.4.
C) It is an important buffer in intracellular fluid.
D) It cannot function in the presence of strong acids.

A

C) It is an important buffer in intracellular fluid.

68
Q

Which of the following is a true characteristic of weak acids in buffer solutions?
A) They fully dissociate in water.
B) They only partially dissociate in water.
C) They do not dissociate at all in water.
D) They increase the pH of the solution when added to water.

A

B) They only partially dissociate in water.

69
Q

What is buffer capacity?
A) The pH of the buffer solution
B) The ability of a buffer to resist pH change
C) The total concentration of the buffer solution
D) The range of pH values over which a buffer is effective

A

B) The ability of a buffer to resist pH change

69
Q

Which of the following factors increases the buffer capacity of a solution?
A) Increasing the volume of the buffer
B) Increasing the concentration of the buffering components
C) Decreasing the concentration of the buffering components
D) Increasing the temperature of the buffer solution

A

B) Increasing the concentration of the buffering components

69
Q

Which of the following correctly describes the relationship between pH and buffer capacity? A) A higher pH always means a higher buffer capacity.
B) pH and buffer capacity are the same properties.
C) A buffer with the same pH can have different buffer capacities.
D) Buffer capacity does not depend on the concentration of the buffer.

A

C) A buffer with the same pH can have different buffer capacities.

70
Q

In the carbonic acid-bicarbonate buffer system, what happens when CO₂ levels in the blood increase?
A) The pH of the blood increases significantly.
B) The pH of the blood decreases slightly.
C) The buffer capacity of the blood decreases.
D) The concentration of HCO₃⁻ in the blood decreases.

A

B) The pH of the blood decreases slightly.

71
Q

Which of the following correctly describes the role of the kidneys in the carbonic acid-bicarbonate buffer system?
A) The kidneys eliminate CO₂ from the body.
B) The kidneys supply HCO₃⁻ to maintain buffer capacity.
C) The kidneys convert H₂CO₃ into H₂O and CO₂.
D) The kidneys are not involved in the carbonic acid-bicarbonate buffer system.

A

B) The kidneys supply HCO₃⁻ to maintain buffer capacity.

71
Q

Which of the following statements is true regarding the buffer range? A) The buffer range is the same for all buffers.
B) The buffer range is typically within ±1 pH unit of the pKa of the acid.
C) The buffer range is dependent solely on the concentration of the buffer.
D) The buffer range extends from pH 0 to pH 14.

A

B) The buffer range is typically within ±1 pH unit of the pKa of the acid.

71
Q

What happens to blood pH when CO₂ levels rise in the body?
A) The pH increases, leading to alkalosis.
B) The pH decreases, leading to acidosis.
C) The pH remains unchanged.
D) The pH decreases, leading to alkalosis.

A

B) The pH decreases, leading to acidosis.

71
Q

Which condition is caused by a decrease in CO₂ levels in the blood? A) Acidosis
B) Alkalosis
C) Hypoxia
D) Hypercapnia

A

B) Alkalosis

72
Q

Which of the following describes the bicarbonate buffer system’s role when blood pH needs to be lowered?
A) The kidneys excrete HCO₃⁻.
B) The lungs excrete CO₂.
C) The kidneys excrete H⁺ ions.
D) The lungs retain CO₂.

A

D) The lungs retain CO₂.

73
Q

What is the role of the enzyme carbonic anhydrase in the bicarbonate buffer system?
A) It catalyzes the conversion of CO₂ and H₂O into carbonic acid.
B) It catalyzes the dissociation of HCO₃⁻ into CO₂ and H₂O.
C) It inhibits the formation of H⁺ ions.
D) It increases the pH of the blood.

A

A) It catalyzes the conversion of CO₂ and H₂O into carbonic acid.

73
Q

How do the lungs and kidneys collaborate in regulating blood pH through the bicarbonate buffer system?
A) The lungs excrete H⁺ ions, and the kidneys excrete CO₂.
B) The lungs excrete CO₂, and the kidneys excrete HCO₃⁻ or H⁺ ions as needed.
C) The kidneys excrete CO₂, and the lungs excrete HCO₃⁻.
D) Both the lungs and kidneys excrete CO₂.

A

B) The lungs excrete CO₂, and the kidneys excrete HCO₃⁻ or H⁺ ions as needed.

74
Q

Which of the following reactions occurs in the bicarbonate buffer system to lower blood pH?
A) CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺
B) H₂CO₃ → CO₂ + H₂O
C) HCO₃⁻ + H⁺ → H₂CO₃
D) NaOH + H₂CO₃ → NaHCO₃ + H₂O

A

A) CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺

74
Q

What physiological response might occur if a person experiences hyperventilation?
A) CO₂ levels increase, leading to acidosis.
B) CO₂ levels decrease, leading to alkalosis.
C) Blood pH decreases due to increased CO₂.
D) HCO₃⁻ levels rise, leading to acidosis.

A

B) CO₂ levels decrease, leading to alkalosis.

75
Q

What happens when a base is added to the blood in the presence of a protein buffer?
A) The -COO⁻ groups neutralize the base.
B) The -NH₃⁺ groups neutralize the base.
C) The phosphate buffer takes over.
D) The carbonic acid buffer system is activated.

A

B) The -NH₃⁺ groups neutralize the base.

75
Q

What role do amino acids play in the protein buffer system?
A) They release OH⁻ ions to neutralize acids.
B) They accept or release H⁺ ions in response to pH changes.
C) They produce CO₂ to buffer acids.
D) They only function in extracellular fluid.

A

B) They accept or release H⁺ ions in response to pH changes.

75
Q

Why is the carbonic acid buffer system’s buffering power considered weak at the pH of blood?
A) Because the pKa of carbonic acid is much higher than the blood pH.
B) Because the pKa of carbonic acid is much lower than the blood pH.
C) Because the pKa of carbonic acid is close to the pH of blood.
D) Because the pKa of carbonic acid is equal to the blood pH.

A

B) Because the pKa of carbonic acid is much lower than the blood pH.

75
Q

What is one limitation of the carbonic acid buffer system?
A) It does not require a functioning respiratory system.
B) It can only buffer bases, not acids.
C) It is limited by the availability of bicarbonate ions.
D) It functions independently of the pKa of carbonic acid.

A

C) It is limited by the availability of bicarbonate ions.

76
Q

Which buffer system is most effective in the intracellular fluid (ICF) and renal tubules?
A) Carbonic acid buffer
B) Phosphate buffer
C) Bicarbonate buffer
D) Protein buffer

A

B) Phosphate buffer

76
Q

Why is the phosphate buffer system not highly effective in extracellular fluid (ECF)?
A) It has a pKa that is too far from the pH of ECF.
B) It is not present in high concentrations in ECF.
C) It only buffers acids, not bases.
D) It is only active in the lungs.

A

B) It is not present in high concentrations in ECF.

77
Q

What is the primary function of the lungs in relation to the carbonic acid buffer system?
A) To increase bicarbonate concentration.
B) To excrete H⁺ ions directly.
C) To excrete CO₂, thereby reducing carbonic acid levels.
D) To produce carbonic anhydrase.

A

C) To excrete CO₂, thereby reducing carbonic acid levels.

77
Q

Which of the following best describes the function of the respiratory system in pH regulation?
A) It only affects fixed acids like lactic acid.
B) It directly eliminates hydrogen ions from the body.
C) It adjusts body pH by changing the rate and depth of breathing.
D) It is ineffective in regulating volatile acids.

A

C) It adjusts body pH by changing the rate and depth of breathing.

77
Q

What role does hemoglobin play in maintaining blood pH?
A) It only binds to oxygen.
B) It acts as a buffer by binding to CO₂ and hydrogen ions.
C) It regulates pH by excreting lactic acid.
D) It transports bicarbonate ions in the blood.

A

B) It acts as a buffer by binding to CO₂ and hydrogen ions.

78
Q

What happens to the pH of the blood during hyperventilation?
A) pH decreases due to increased CO₂.
B) pH remains unchanged.
C) pH increases due to the removal of CO₂.
D) pH decreases due to increased hydrogen ion concentration.

A

C) pH increases due to the removal of CO₂.

78
Q

Which acid is NOT regulated by the respiratory system?
A) Carbonic acid
B) Lactic acid
C) H₂CO₃
D) CO₂

A

B) Lactic acid

79
Q

How does hypoventilation affect blood pH?
A) It decreases CO₂ levels, increasing blood pH.
B) It increases CO₂ levels, decreasing blood pH.
C) It has no effect on blood pH.
D) It increases bicarbonate ion concentration.

A

B) It increases CO₂ levels, decreasing blood pH.

79
Q

What happens to the body’s pH if the kidneys fail to function properly?
A) The pH of the body remains stable.
B) The respiratory system compensates fully for the kidney failure.
C) The pH balance fails, leading to acidosis or alkalosis.
D) The kidneys begin to regulate CO₂ instead.

A

C) The pH balance fails, leading to acidosis or alkalosis.

80
Q

Which system is most effective in regulating the body’s pH?
A) Respiratory system
B) Digestive system
C) Renal system
D) Nervous system

A

C) Renal system

80
Q

What is the primary function of the kidneys in pH regulation?
A) To excrete volatile acids like CO₂.
B) To conserve and produce bicarbonate ions.
C) To eliminate CO₂ through exhalation.
D) To regulate blood pressure by removing bicarbonate.

A

B) To conserve and produce bicarbonate ions.

81
Q

What is the primary base regulated by the kidneys in the body?
A) NaCl
B) H₂CO₃
C) HCO₃⁻
D) CO₂

A

C) HCO₃⁻

82
Q

Why is the regeneration of bicarbonate important in the renal regulation of pH?
A) It increases CO₂ production.
B) It prevents the depletion of the body’s buffering capacity.
C) It enhances the filtration rate in the kidneys.
D) It decreases the production of hydrogen ions.

A

B) It prevents the depletion of the body’s buffering capacity.

82
Q

What must happen for bicarbonate formation to continue in the kidneys?
A) CO₂ must be retained in the body.
B) Hydrogen ions must be removed.
C) Bicarbonate must be excreted.
D) Water must be retained in the body.

A

B) Hydrogen ions must be removed.

82
Q

Where does the regeneration of bicarbonate primarily occur in the kidneys?
A) Glomerulus
B) Renal tubules
C) Renal cortex
D) Renal medulla

A

B) Renal tubules

83
Q

What would happen if the kidneys did not regenerate bicarbonate?
A) The body would become alkalotic.
B) The buffering capacity of the body would be depleted, leading to acidosis.
C) CO₂ levels in the blood would increase dramatically.
D) The filtration rate in the kidneys would decrease.

A

B) The buffering capacity of the body would be depleted, leading to acidosis.

84
Q

How much bicarbonate is typically filtered through the glomerulus in 24 hours?
A) 1000 mmol
B) 2100 mmol
C) 3200 mmol
D) 4300 mmol

A

D) 4300 mmol

85
Q

In a healthy body, what happens to the bicarbonate filtered by the kidneys?
A) It is mostly excreted in urine.
B) It is entirely lost, causing alkalosis.
C) Virtually all of it is recovered.
D) It is converted to CO₂.

A

C) Virtually all of it is recovered.

86
Q

Which enzyme is involved in renal bicarbonate regeneration?
A) Amylase
B) Carbonic anhydrase
C) Lactase
D) Pepsin

A

B) Carbonic anhydrase

87
Q

What are the renal responses to acidosis?
A) Increased production of bicarbonate
B) Decreased reabsorption of bicarbonate
C) Increased excretion of ammonia
D) Decreased excretion of titratable acids

A

C) Increased excretion of ammonia

87
Q

Why is the luminal side of renal tubular cells significant in bicarbonate regeneration?
A) It is highly permeable to bicarbonate ions.
B) It is impermeable to bicarbonate ions.
C) It secretes bicarbonate into the urine.
D) It converts bicarbonate into CO₂.

A

B) It is impermeable to bicarbonate ions.

88
Q

Which of the following is NOT a renal response to acidosis?
A) Increased reabsorption of bicarbonate
B) Increased excretion of titratable acids
C) Increased production of ammonia
D) Decreased production of bicarbonate

A

D) Decreased production of bicarbonate

88
Q

How long does it generally take for the effects of renal responses to acidosis to become appreciable?
A) Immediately
B) 1-2 hours
C) 12-24 hours
D) 48-72 hours

A

C) 12-24 hours

89
Q

What happens to CO₂ formed from carbonic acid in the renal tubular lumen?
A) It is excreted in the urine.
B) It diffuses across the luminal membrane into the tubular cells.
C) It remains in the lumen to neutralize acids.
D) It is converted back into bicarbonate.

A

B) It diffuses across the luminal membrane into the tubular cells.

90
Q

Which process is catalyzed by carbonic anhydrase in the kidneys? A) Conversion of bicarbonate to CO₂ and H₂O
B) Conversion of CO₂ and H₂O to bicarbonate
C) Conversion of ammonia to ammonium
D) Conversion of titratable acids to water

A

A) Conversion of bicarbonate to CO₂ and H₂O

91
Q

What is the initial step in the renal reabsorption of filtered bicarbonate (HCO₃⁻) during acidosis?
A) H⁺ is secreted into the renal tubule.
B) CO₂ combines with water within renal tubular cells.
C) H₂CO₃ dissociates into H⁺ and HCO₃⁻.
D) HCO₃⁻ enters the bloodstream.

A

B) CO₂ combines with water within renal tubular cells.

92
Q

What happens to the hydrogen ion (H⁺) after it is formed from the dissociation of carbonic acid (H₂CO₃) within renal tubular cells?
A) It is excreted directly into the bloodstream.
B) It is secreted into the renal tubule.
C) It is converted back to CO₂.
D) It remains in the renal tubular cells.

A

B) It is secreted into the renal tubule.

93
Q

What is the final fate of NH₄⁺ formed in the renal tubules during acidosis?
A) It is reabsorbed into the bloodstream.
B) It is converted back into NH₃.
C) It is excreted in the urine.
D) It is converted into urea in the kidneys.

A

C) It is excreted in the urine.

93
Q

During acidosis, what role does the phosphate buffer play in the renal excretion of acids? A) It helps reclaim bicarbonate ions.
B) It forms carbonic acid in the renal tubule.
C) It combines with H⁺ to form H₂PO₄⁻, which is excreted in the urine.
D) It neutralizes ammonia in the renal tubule.

A

C) It combines with H⁺ to form H₂PO₄⁻, which is excreted in the urine.

94
Q

How is ammonia (NH₃) produced in the kidneys during acidosis?
A) Through the direct secretion of ammonia from the renal tubular cells.
B) By the deamination of glutamine within the mitochondria of proximal tubular cells.
C) By the breakdown of urea in the renal tubules.
D) By the reabsorption of NH₄⁺ from the urine.

A

B) By the deamination of glutamine within the mitochondria of proximal tubular cells.

95
Q

During alkalosis, how do the kidneys help to restore acid-base balance?
A) By increasing the excretion of bicarbonate ions and reclaiming hydrogen ions.
B) By increasing the reabsorption of bicarbonate ions.
C) By decreasing the excretion of titratable acids.
D) By increasing the production of ammonia.

A

A) By increasing the excretion of bicarbonate ions and reclaiming hydrogen ions.

96
Q
A
97
Q
A
98
Q
A

Bio Mol prelims (4 decks)

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