BCCB2000 Lecture 3 Questions

Question 1

Water has no effect on the hydrophobic parts of an amphipathic molecule. True or False?

Answer 1

False

Question 2

Molecules that are both hydrophobic and hydrophilic are ________.

Answer 2

amphipathic

Question 3

Water has no effect on the structures of macromolecules True or False?

Answer 3

False

Question 4

What is the pH of a 10-4 M solution of HCl?

Answer 4

4

Question 5

The pH of a sample of blood is 7.4. The pH of a sample of gastric juice is 1.4. The blood sample has: A. a million times lower [H+] than the gastric juice. B. 6 times lower [H+] than the gastric juice. C. 5.29 times lower [H+] than the gastric juice. D. 6,000 times lower [H+] than the gastric juice. E. 0.189 times the [H+] as the gastric juice.

Answer 5

A. a million times lower [H+] than the gastric juice.

Question 6

Cells (e.g. red blood cells) may be incubated, without losing their integrity or shape, in a 150mM solution of NaCl but not with 300mM urea. Select the most appropriate statements below. A. A 300mM solution of urea is isosmotic to a solution of 150mM NaCl. B. The 300mM urea solution is isotonic to cells. C. The cells are essentially impermeable to 150mM NaCl D. The 300mM urea solution is hypotonic to cells E. The 300mM urea solution is toxic to cells F. The 150mM NaCl solution is hypotonic to cells G. The 150mM NaCl solution is isotonic to cells

Answer 6

A, C, D, G

Question 7

The properties of cellular macromolecules are influenced by changes in pH. True or False?

Answer 7

True

Question 8

Which statement does not explain the polarity of water? A. Oxygen is more electronegative than hydrogen. B. Water molecules have a bent geometry (V-shape). C. The oxygen in water has sp2 hybrid orbitals. D. In water the hydrogen carries a partial positive charge (δ+)

Answer 8

C. The oxygen in water has sp2 hybrid orbitals.

Question 9

Oil and water do not form a solution due to ________. A. the hydrophobic effect B. the inability of oil to hydrogen bond with water C. the nonpolarity of oil D. A, B, & C E. A and C only

Answer 9

D. A, B, & C

Question 10

Water is excluded from cellular membranes and does not contribute to the stability of membrane structures. True or False?

Answer 10

False

Question 11

Dissolved solutes alter some physical properties of the solvent water because they: A. change the temperature of the water. B. change the hydrogen bonding of the water. C. change the concentration of the water. D. change the ionic bonding of the water. E. change the pH of the water.

Answer 11

C. change the concentration of the water.

Question 12

Which of the following statements correctly describe water and hydrogen bonds: A. Water molecules can form hydrogen bonds with hydrogen atoms attached by covalent bonds to oxygen and carbon atoms but not to those of nitrogen B. Hydrogen bonds are important in biochemistry because, although weak, they are numerous and can be made and broken relatively easily and rapidly C. Hydrogen bonds occur between water molecules in the liquid state but not in ice D. The occurrence of hydrogen bonds between water molecules gives liquid water a regular three dimensional structure E. A water molecule can act as a hydrogen bond donor but not a hydrogen bond acceptor

Answer 12

B. Hydrogen bonds are important in biochemistry because, although weak, they are numerous and can be made and broken relatively easily and rapidly

Question 13

The solution equilibrium constant (Keq) for water is 1.8 x 10-16M. However, the ioinization equilibrium constant (Kw) for water is 1.0 x 10-14M2. Why? A. The solution equilibrium (Keq) includes the concentration of water B. There are more reactants than products in the ionization equilibrium (Kw) compared with the solution (Keq) equilibrium C. The ionization equilibrium (Kw) includes the concentration of water D. The concentration of water is effectively a constant E. There are more reactants than products in the solution (Keq) equilibrium compared with the ionization (Kw) equilibrium F. The ionization equilibrium constant (Kw) is multiplied by 55.5M G. The solution equilibrium constant (Keq) is multiplied by 55.5M

Answer 13

C, D, G

Question 14

Which of the following is true about the properties of aqueous solutions? A. Hydrogen bonds form readily in aqueous solutions. B. Charged molecules are generally insoluble in water. C. An increase in pH from 5.0 to 6.0 reflects an increase in the hydroxide ion concentration ([OH-]) of 20%. D. A decrease in pH from 8.0 to 6.0 reflects a decrease in the proton concentration ([H+]) by a factor of 100.

Answer 14

A. Hydrogen bonds form readily in aqueous solutions.

Question 15

Why do electrolytes dissolve readily in water?

Answer 15

water molecules can cluster about cations and anions

Question 16

Compare solution A with pH = 4 to solution B with pH = 6 A. The concentration of hydronium ion in solution A is 100 times that in solution B B. The hydroxide concentrations are equal in the two solutions since pH only measures the concentration of H+. C. Solution A has greater buffering capacity than solution B D. The concentration of hydronium ion in solution A is twice that in solution B

Answer 16

A. The concentration of hydronium ion in solution A is 100 times that in solution B

Question 17

Oxygen has very good solubility in water and that is how oxygen can be transported easily in blood plasma in humans. True or False?

Answer 17

False

Question 18

Choose the incorrect statement about water: A. pure water is always pH 7 B. pure water is neutral and has a concentration of H+ ions of 10-7M at 25°C C. pure water can change pH when exposed to air D. pure water has a pH of 7 at 25°C E. water can have a pH that is not pH 7

Answer 18

A. pure water is always pH 7

Question 19

The abundance of water in the cells and tissues helps to minimize temperature fluctuations. This is due to what property of water? A. density B. viscosity C. specific heat D. boiling point

Answer 19

C. specific heat

Question 20

Which substance do you expect to be most soluble in water? A. ammonia, NH3 B. methane, CH4 C. carbon dioxide, CO2 D. nitrogen, N2

Answer 20

A. ammonia, NH3

Question 21

Select from the following the correct statements concerning diffusion A. The solute and solvent molecules in solution are constantly moving and self-propelled by thermal energy gained from their environment. B. Diffusion is the non-random transport of molecules (solute) in bulk solvent (usually water). C. Diffusion results in a thorough mixing of the solute molecules within the solvent D. Solutes diffuse from an area of low concentration to an area of high concentration

Answer 21

A. The solute and solvent molecules in solution are constantly moving and self-propelled by thermal energy gained from their environment. AND C. Diffusion results in a thorough mixing of the solute molecules within the solvent

Question 22

How does the ion-product of water, Kw, relate to the equilibrium constant, Keq, for the dissociation reaction of water? A. Kw is found by multiplying Keq by the concentration of water B. Kw just another symbol for Keq , so they are equal C. Kw is found by dividing Keq by the ideal gas constant D. Kw is found by multiplying Keq by the concentrations of hydronium ion and hydroxide ion.

Answer 22

A. Kw is found by multiplying Keq by the concentration of water

Question 23

Use the words: isotonic, hypertonic, and hypotonic to complete the following paragraphs. You may use a word more than once. An [a] solution has the same osmolarity as the solution to which it is being compared. A [b] solution has a lower osmolarity than the solution to which it is being compared. A [c] solution has a higher osmolarity than the solution to which it is being compared. Higher osmolarity results in osmotic pressure, which generally leads to movement of water across a membrane. In an [d] solution, in which the osmolarity of the solution is the same as the cell cytoplasm, there will be no net water movement. In a [e] solution, water will move into the cell, causing the cell to swell and possibly burst. In a [f] solution, water will move out of the cell and it will shrink.

Answer 23

Specified Answer for: a isotonic Specified Answer for: b hypotonic Specified Answer for: c hypertonic Specified Answer for: d isotonic Specified Answer for: e hypotonic Specified Answer for: f hypertonic

Question 24

The hydrogen ion (also known as a ‘proton’) is hydrated and essentially exists minimally as H3O+ in aqueous solution True or False?

Answer 24

True

Question 25

What is osmosis?

Answer 25

movement of a water molecule across a membrane.

Question 26

The aqueous solution with the lowest pH is: A. 0.1 M acetic acid (pKa = 4.86). B. 0.1 M formic acid (pKa = 3.75). C. 10-12 M NaOH. D. 0.1 M HCl.

Answer 26

D. 0.1 M HCl.

Question 27

Compounds that ionize when dissolved in water are called ________.

Answer 27

electrolytes

Question 28

Which of the following statements describe water in the body: A. Changes to water content in a human are usually well tolerated B. Water accounts for more than one half of the mass of a human body C. Most of the water in the body is inside cells D. Water in an organism acts as an inert solvent and does not take part in reactions.

Answer 28

B and C

Question 29

The ratio of the concentration of a ________ over ________ describes the proportions of forms of a weak acid necessary to satisfy the Henderson-Hasselbalch equation.

Answer 29

conjugate base; conjugate acid OR proton acceptor; proton donor

Question 30

Water derives most of its properties from its: A. high boiling point and melting point B. cohesiveness and adhesiveness C. high dielectric constant D. polarity and hydrogen-bonding capacity E. small degree of ionization

Answer 30

D. polarity and hydrogen-bonding capacity

Question 31

A hydronium ion: A. is a hydrated proton B. is a hydrated hydrogen ion C. has the structure H3O+ D. is the usual form of one of the dissociation products of water in solution E. All of the above are true

Answer 31

E. All of the above are true

Question 32

Solutes diffuse more slowly in cytoplasm than in water because of: A. the higher viscosity of water B. the higher heat of vaporization of water C. the presence of many crowded molecules in the cytoplasm D. the absence of charged molecules inside cells

Answer 32

C. the presence of many crowded molecules in the cytoplasm

Question 33

The Henderson-Hasselbalch equation can be used to calculate: A. the pH of a solution of an organic acid B. the amount of salt and acid to add to form a specific buffer C. the pKa of a weak acid D. A, B, and C above

Answer 33

D. A, B, and C above

Question 34

Which of the following statements correctly describe the solvent properties of water: A. Water can easily dissolve non-polar molecules B. The attractive electrostatic forces between ions of different charge (such as Na+ and Cl-) are increased in water C. Molecules such as glucose which have many hydroxyl functional groups are very soluble in water D. The repulsive electrostatic forces between ions of the same charge (such as Na+ and K+) in water are decreased in water E. Water promotes the ionization of acids such as acetic acid

Answer 34

C. Molecules such as glucose which have many hydroxyl functional groups are very soluble in water D. The repulsive electrostatic forces between ions of the same charge (such as Na+ and K+) in water are decreased in water E. Water promotes the ionization of acids such as acetic acid