🧪 Biochemistry MCQ Quiz Hub

1. Which of the following organic groups are found in naturally occuring amino acids?
Guanidinium ion
Indole
Imidazole
All of these

2. Polyprotic acids such as H3PO4; can act as acid-base buffers
only in combination with polyprotic bases
if their concentration is kept low
at pH values around neutrality
at pH values around any of their pKa's

3. The pH of a solution is determined by
concentration of salt
relative concentration of acids and bases
dielectric constant of the medium
environmental effect

4. The reactions of molecules
are the reactions of the functional groups
are independent of the functional groups
require an enzyme in all cases
All of the above

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?
Michaelis-Menten equation
Haldanes equation
Henderson-Hasselbalch equation
Hardy-Windberg law

6. Molecules in which the atoms are held together by __________ bonds have the strongest chemical linkages.
noncovalent
covalent
ionic
hydrogen

7. Salt dissolves well in water as water molecules
form hydrogen bonds with the positively and negatively charged ions
make nonpolar covalent bonds with the positively charged ions only
surround the ions because of their charge but do not form hydrogen bonds
share electrons with the ions to make polar covalent bonds

8. Buffer solutions
will always have a pH of 7
are rarely found in living systems
cause a decrease in pH when acids are added to them.
tend to maintain a relatively constant pH.

9. A Bronsted acid becomes __________ upon losing a proton.
highly reactive
ts conjugate acid
its conjugate base
a hydronium ion

10. Most of the important functional groups in biological molecules contain
oxygen and/or nitrogen and are acidic
oxygen and a phosphate
nitrogen and a phosphate
oxygen and/or nitrogen and are polar

11. What is the concentration; in moles/liter; of the hydrogen ion; if pH of a solution is 7?
7
7 x 10-7
5 x 10-7
1 x 10-7

12. Which of the following alcohols would be most soluble in water?
methanol
ethanol
butanol
octanol

13. Which of the following acid/base pairs act as natural buffers in living systems?
H2CO3/HCO3-
H2PO4-/HPO42-
Histidine+/histidine
All of these

14. If protein is made exclusively from nonpolar amino acids; then it will this protein interact with water?
be repelled by water
It will be attracted to water
It will form a membrane in water
It will act as a buffer and stabilize the pH

15. A compound that is capable of forming hydrogen bonds with water
is probably held together by noncovalent bonds
contains at least some polar covalent bonds
should act as a good buffer for acids and bases
does not dissolve well in water

16. A biological polymer contains alanine; tyrosine; and lysine. Which of the following will be true about this molecule?
DNA
Strong base
Phospholipid
Protein

17. The effectiveness or capacity of a buffer solution can be affected by
molar concentration of the buffer components
concentration of the conjugate base to the weak acid
both (a) and (b)
temperature of buffer components

18. Who discovered and described the blood groups (ABO) classification?
Theodor Kocher
Karl Landsteiner
Otto Warburg
Karl Hooper

19. Hydrogen bonds and hydrophilic interactions are types of
weak chemical bonds that hold together the atoms within a molecule
strong chemical bonds that hold together the atoms within a molecule
weak chemical bonds that link together separate molecules
strong chemical bonds that link together separate molecules

20. H2O and CH4 are both examples of
molecules
ions
acids
none of these

21. A solution with pH = 5 is __________ than a solution with pH = 7.
2 times more basic
10 times more basic
10 times more basic
100 times more basic

22. The lone pair electrons on oxygen in a H20 molecule
carry a partial positive charge
are not important for the properties of water
carry a partial negative charge
form covalent bonds in ice

23. Which of the following statements about water is correct?
It is critical for many of the chemical processes found in living systems
Polar substances that can form hydrogen bonds will dissolve in it
Nonpolar substances like oils are not soluble in it
All of the above

24. The strength of an acid depends on
number of neutrons gain
electronegativity
number of double bonds
number of protons released

25. Which of the following statements about covalently bonded molecules is false?
Electrons are shared between the atoms that make up the molecule
Noncovalent bonds may also be present; especially if the molecule is large
Such molecules often result from the interaction of ionized atoms
The chemical bonds that hold the molecule together are relatively strong

26. Which of the following character does not apply to water?
The water molecule is asymmetric
The water molecule readily forms hydrophobic interactions
The covalent bonds in water are highly polarized
All three atoms in the water molecule readily form hydrogen bonds

27. The dissociation constant of H2O at 25° C is
10-14 M
1014 M
10-7 M
107 M

28. Weak acids generally have pKa
values less than 1
pKa values greater than 2
been seldom found in living systems
that cannot be used to buffer

29. The reason that fats contain more energy than simple sugars; is fats have many more
carbon atoms
hydrogen atoms
covalent bonds
hydrogen bonds

30. The main difference between an acid and a base is that
bases are polar molecules and acids are not
acids are polar molecules and bases are not
. bases donate hydrogen ions in water while acids accept hydrogen ions
acids donate hydrogen ions in water while bases accept hydrogen ions

31. The elements oxygen; nitrogen; and carbon
can all form covalent bonds with other elements
contain protons and neutrons in their atomic nuclei
are common elements in the molecules that make up living organisms
All of the above