MCB 450 EXAM 1 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Question:
1. Why is water considered a polar molecule?
Answer:
Oxygen is more electronegative than hydrogen creating an unequal distribution of electrons and a dipole
moment
Question:
2. What property of water allows it to dissolve ionic compounds?
Answer:
Its polarity stabilizes separated ions through hydration shells
Question:
3. What is the biological significance of hydrogen bonding in water?
Answer:
It contributes to protein folding DNA stability and high heat capacity
Question:
4. Rank the following interactions from strongest to weakest: hydrogen bonds van der Waals interactions
covalent bonds ionic interactions
Answer:
Covalent > Ionic > Hydrogen Bond > Van der Waals
Question:
5. Why are hydrophobic interactions considered entropy-driven?
Answer:
Clustering hydrophobic molecules releases ordered water molecules increasing system entropy
Question:
6. What is the major force driving membrane formation?
Answer:
The hydrophobic effect
Question:
7. Define a Brønsted-Lowry acid
Answer:
A proton donor
Question:
8. Define a Brønsted-Lowry base
Answer:
A proton acceptor
, Question:
9. What happens to a weak acid when the pH increases above its pKa?
Answer:
It becomes increasingly deprotonated
Question:
10. What is the relationship between pH and proton concentration?
Answer:
pH = -log[H■]
Question:
11. If [H■] increases tenfold how does pH change?
Answer:
It decreases by 1 unit
Question:
12. What does pKa represent?
Answer:
The pH at which half of the acid is protonated and half is deprotonated
Question:
13. At what pH is buffering most effective?
Answer:
At pH = pKa
Question:
14. Using Henderson-Hasselbalch what is the ratio of A■ to HA when pH = pKa + 1?
Answer:
10:1
Question:
15. What is the ratio of A■ to HA when pH = pKa - 1?
Answer:
1:10
Question:
16. Why are biological buffers important?
Answer:
They resist sudden pH changes that could alter protein function
Question:
17. What occurs at the half-equivalence point of a titration?
Answer:
pH = pKa
CORRECT ANSWERS
Question:
1. Why is water considered a polar molecule?
Answer:
Oxygen is more electronegative than hydrogen creating an unequal distribution of electrons and a dipole
moment
Question:
2. What property of water allows it to dissolve ionic compounds?
Answer:
Its polarity stabilizes separated ions through hydration shells
Question:
3. What is the biological significance of hydrogen bonding in water?
Answer:
It contributes to protein folding DNA stability and high heat capacity
Question:
4. Rank the following interactions from strongest to weakest: hydrogen bonds van der Waals interactions
covalent bonds ionic interactions
Answer:
Covalent > Ionic > Hydrogen Bond > Van der Waals
Question:
5. Why are hydrophobic interactions considered entropy-driven?
Answer:
Clustering hydrophobic molecules releases ordered water molecules increasing system entropy
Question:
6. What is the major force driving membrane formation?
Answer:
The hydrophobic effect
Question:
7. Define a Brønsted-Lowry acid
Answer:
A proton donor
Question:
8. Define a Brønsted-Lowry base
Answer:
A proton acceptor
, Question:
9. What happens to a weak acid when the pH increases above its pKa?
Answer:
It becomes increasingly deprotonated
Question:
10. What is the relationship between pH and proton concentration?
Answer:
pH = -log[H■]
Question:
11. If [H■] increases tenfold how does pH change?
Answer:
It decreases by 1 unit
Question:
12. What does pKa represent?
Answer:
The pH at which half of the acid is protonated and half is deprotonated
Question:
13. At what pH is buffering most effective?
Answer:
At pH = pKa
Question:
14. Using Henderson-Hasselbalch what is the ratio of A■ to HA when pH = pKa + 1?
Answer:
10:1
Question:
15. What is the ratio of A■ to HA when pH = pKa - 1?
Answer:
1:10
Question:
16. Why are biological buffers important?
Answer:
They resist sudden pH changes that could alter protein function
Question:
17. What occurs at the half-equivalence point of a titration?
Answer:
pH = pKa
