MCQs BIOCHEMISTRY: water and macromolecule

1.
Which of the following organic groups are found in naturally occuring amino acids?
A. Guanidinium ion
B. Indole
C. Imidazole
D. All of these
Answer & Explanation
Answer: Option D


2. 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
Answer & Explanation
Answer: Option D

3. 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
Answer & Explanation
Answer: Option B

4. 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
Answer & Explanation
Answer: Option A

5. 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
Answer & Explanation
Answer: Option C

6. Molecules in which the atoms are held together by __________ bonds have the strongest chemical linkages.
A. noncovalent B. covalent
C. ionic D. hydrogen
Answer & Explanation
Answer: Option B

7.
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
Answer & Explanation
Answer: Option C

8.
Buffer solutions

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.
Answer & Explanation
Answer: Option D

9.
A Bronsted acid becomes __________ upon losing a proton.

A. highly reactive
B. its conjugate acid
C. its conjugate base
D. a hydronium ion
Answer & Explanation
Answer: Option C


10.
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
Answer & Explanation
Answer: Option D

 

11.
What is the concentration, in moles/liter, of the hydrogen ion, if pH of a solution is 7?
A. 7
B. 7 x 10-7
C. 5 x 10-7
D. 1 x 10-7
Answer & Explanation
Answer: Option D

12.
Which of the following alcohols would be most soluble in water?
A. methanol B. ethanol
C. butanol D. octanol
Answer & Explanation
Answer: Option A


13.
Which of the following acid/base pairs act as natural buffers in living systems?
A. H2CO3/HCO3-
B. H2PO4-/HPO42-
C. Histidine+/histidine
D. All of these
Answer & Explanation
Answer: Option D

14.
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
Answer & Explanation
Answer: Option A


15.
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
Answer & Explanation
Answer: Option B

 

16.
A biological polymer contains alanine, tyrosine, and lysine. Which of the following will be true about this molecule?

A. DNA
B. Strong base
C. Phospholipid
D. Protein
Answer & Explanation
Answer: Option D

17.
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
Answer & Explanation
Answer: Option C

18.
Who discovered and described the blood groups (ABO) classification?

A. Theodor Kocher
B. Karl Landsteiner
C. Otto Warburg
D. Karl Hooper
Answer & Explanation
Answer: Option B

19.
H2O and CH4 are both examples of

A. molecules
B. ions
C. acids
D. none of these
Answer & Explanation
Answer: Option A

20.
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
Answer & Explanation
Answer: Option C

21.
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
Answer & Explanation
Answer: Option D

22.
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
Answer & Explanation
Answer: Option C

23.
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
Answer & Explanation
Answer: Option D


24.
The strength of an acid depends on

A. number of neutrons gain
B. electronegativity
C. number of double bonds
D. number of protons released
Answer & Explanation
Answer: Option B


25.
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
Answer & Explanation
Answer: Option C