Water, pH and Macromolecules MCQs : This section focuses on the "Water, pH and Macromolecules". These Multiple Choice Questions (MCQs) should be practiced to improve the Water, pH and Macromolecules skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Which of the following statements about water is correct?
A. It is critical for many of the chemical processes found in living systems
B. Polar substances that can form hydrogen bonds will dissolve in it
C. Nonpolar substances like oils are not soluble in it
D. All of the above
Hydrogen bonds and hydrophilic interactions are types of
A. weak chemical bonds that hold together the atoms within a molecule
B. strong chemical bonds that hold together the atoms within a molecule
C. weak chemical bonds that link together separate molecules
D. strong chemical bonds that link together separate molecules
A solution with pH = 5 is __________ than a solution with pH = 7.
A. 2 times more basic
B. 10 times more basic
C. 10 times more acidic
D. 100 times more acidic
The pH of a solution is determined by
A. concentration of salt
B. relative concentration of acids and bases
C. dielectric constant of the medium
D. environmental effect
Which of the following acid/base pairs act as natural buffers in living systems?
D. All of these
The main difference between an acid and a base is that
A. bases are polar molecules and acids are not
B. acids are polar molecules and bases are not
C. bases donate hydrogen ions in water while acids accept hydrogen ions
D. acids donate hydrogen ions in water while bases accept hydrogen ions
The effectiveness or capacity of a buffer solution can be affected by
A. molar concentration of the buffer components
B. concentration of the conjugate base to the weak acid
C. both (a) and (b)
D. temperature of buffer components
Which of the following organic groups are found in naturally occuring amino acids?
A. Guanidinium ion
D. All of these
What is the concentration, in moles/liter, of the hydrogen ion, if pH of a solution is 7?
B. 7 x 10-7
C. 5 x 10-7
D. 1 x 10-7
Which of the following indicates that the pK of an acid is numerically equal to the pH of the solution when the molar concentration of the acid and its conjugate base are equal?
A. Michaelis-Menten equation
B. Haldanes equation
C. Henderson-Hasselbalch equation
D. Hardy-Windberg law
A Bronsted acid becomes __________ upon losing a proton.
A. highly reactive
B. its conjugate acid
C. its conjugate base
D. a hydronium ion
The strength of an acid depends on
A. number of neutrons gain
C. number of double bonds
D. number of protons released
Which of the following statements about covalently bonded molecules is false?
A. Electrons are shared between the atoms that make up the molecule
B. Noncovalent bonds may also be present, especially if the molecule is large
C. Such molecules often result from the interaction of ionized atoms
D. The chemical bonds that hold the molecule together are relatively strong
The dissociation constant of H2O at 25° C is
A. 10-14 M
B. 1014 M
C. 10-7 M
D. 107 M
A. will always have a pH of 7
B. are rarely found in living systems
C. cause a decrease in pH when acids are added to them.
D. tend to maintain a relatively constant pH.
Most of the important functional groups in biological molecules contain
A. oxygen and/or nitrogen and are acidic
B. oxygen and a phosphate
C. nitrogen and a phosphate
D. oxygen and/or nitrogen and are polar
The lone pair electrons on oxygen in a H20 molecule
A. carry a partial positive charge
B. are not important for the properties of water
C. carry a partial negative charge
D. form covalent bonds in ice
The reactions of molecules
A. are the reactions of the functional groups
B. are independent of the functional groups
C. require an enzyme in all cases
D. all of the above
If protein is made exclusively from nonpolar amino acids, then it will this protein interact with water?
A. be repelled by water
B. It will be attracted to water
C. It will form a membrane in water
D. It will act as a buffer and stabilize the pH
Molecules in which the atoms are held together by __________ bonds have the strongest chemical linkages.
The reason that fats contain more energy than simple sugars, is fats have many more
A. carbon atoms
B. hydrogen atoms
C. covalent bonds
D. hydrogen bonds
Who discovered and described the blood groups (ABO) classification?
A. Theodor Kocher
B. Karl Landsteiner
C. Otto Warburg
D. Karl Hooper
Weak acids generally have pKa
A. values less than 1
B. pKa values greater than 2
C. been seldom found in living systems
D. that cannot be used to buffer
A biological polymer contains alanine, tyrosine, and lysine. Which of the following will be true about this molecule?
B. Strong base
Polyprotic acids such as H3PO4, can act as acid-base buffers
A. only in combination with polyprotic bases
B. if their concentration is kept low
C. at pH values around neutrality
D. at pH values around any of their pKa's
Which of the following alcohols would be most soluble in water?
A compound that is capable of forming hydrogen bonds with water
A. is probably held together by noncovalent bonds
B. contains at least some polar covalent bonds
C. should act as a good buffer for acids and bases
D. does not dissolve well in water
Salt dissolves well in water as water molecules
A. form hydrogen bonds with the positively and negatively charged ions
B. make nonpolar covalent bonds with the positively charged ions only
C. surround the ions because of their charge but do not form hydrogen bonds
D. share electrons with the ions to make polar covalent bonds
Which of the following will easily dissolve in a polar solvent?
A. gasoline (heptanes & octanes)
D. sodium chloride
Which of the following character does not apply to water?
A. The water molecule is asymmetric
B. The water molecule readily forms hydrophobic interactions
C. The covalent bonds in water are highly polarized
D. All three atoms in the water molecule readily form hydrogen bonds
The elements oxygen, nitrogen, and carbon
A. can all form covalent bonds with other elements
B. contain protons and neutrons in their atomic nuclei
C. are common elements in the molecules that make up living organisms
D. All of the above
H2O and CH4 are both examples of
D. none of these