BIO111 Final Exam Actual Exam V2 | BIO111 General Biology (BIO111
Final Exam) | UCLA
1. Which property of water allows it to resist drastic temperature changes and maintain
homeostasis in organisms?
A. Low surface tension
B. Non-polar covalent bonding
C. High specific heat
D. High density as a solid
Answer: C
Rationale: Water’s high specific heat is due to the energy required to break hydrogen
bonds before molecules can move faster. This allows large bodies of water to stabilize
climate and organisms to maintain internal temperature. This property is vital for
metabolic processes to occur within narrow thermal ranges.
2. In the tertiary structure of a protein, which type of interaction is typically responsible for
forming disulfide bridges?
A. Ionic bonding
B. Hydrogen bonding between the backbone
C. Covalent bonding between cysteine residues
D. Hydrophobic interactions
Answer: C
Rationale: Disulfide bridges are strong covalent bonds formed between the sulfur atoms of
two cysteine side chains. These bonds provide significant stability to the protein’s overall
three-dimensional shape. They are much stronger than hydrogen or ionic interactions
found in other structural levels.
3. Which organelle is responsible for the synthesis of lipids and the detoxification of poisons?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
,Rationale: The smooth endoplasmic reticulum lacks ribosomes and specializes in lipid
synthesis and carbohydrate metabolism. It also plays a critical role in detoxifying drugs and
poisons, especially in liver cells. This contrasts with the rough ER, which focuses primarily
on protein synthesis.
4. According to the Fluid Mosaic Model, what prevents phospholipids from packing too tightly
at low temperatures?
A. Saturated fatty acids
B. Integral proteins
C. Peripheral proteins
D. Cholesterol
Answer: D
Rationale: Cholesterol acts as a fluidity buffer within the plasma membrane by hindering
the close packing of phospholipids. At low temperatures, it prevents solidification by
maintaining space between the lipids. Conversely, it reduces fluidity at high temperatures
by restricting movement.
5. A cell is placed in a solution where the solute concentration is higher than inside the cell.
The solution is:
A. Hypertonic
B. Isotonic
C. Hypotonic
D. None of the above
Answer: A
Rationale: A hypertonic solution has a higher concentration of non-penetrating solutes
compared to the cell’s interior. This causes water to leave the cell via osmosis, leading to
cell shrinkage or plasmolysis. Understanding tonicity is essential for grasping how cells
manage water balance.
6. Which molecule acts as the final electron acceptor in aerobic cellular respiration?
A. NAD+
B. FAD
C. Oxygen
D. Water
Answer: C
, Rationale: In the electron transport chain, oxygen accepts low-energy electrons and
combines with hydrogen ions to form water. This step is crucial because it allows the chain
to continue functioning by removing electrons. Without oxygen, the production of ATP via
oxidative phosphorylation would cease.
7. During glycolysis, what is the net gain of ATP per molecule of glucose?
A. 32 ATP
B. 4 ATP
C. 2 ATP
D. 36 ATP
Answer: C
Rationale: Glycolysis requires an initial investment of 2 ATP molecules to activate glucose.
Although 4 ATP are produced by substrate-level phosphorylation, the net result is only 2
ATP. This pathway serves as the foundational metabolic step for both aerobic and
anaerobic respiration.
8. Where do the light-dependent reactions of photosynthesis take place within the
chloroplast?
A. Thylakoid membrane
B. Stroma
C. Inner membrane space
D. Outer membrane
Answer: A
Rationale: The light reactions occur in the thylakoid membranes where chlorophyll and
other pigments are located. These pigments capture solar energy to produce ATP and
NADPH. These products are then utilized in the Calvin cycle occurring in the stroma.
9. If a DNA sample contains 20% Cytosine, what percentage of the sample is Adenine?
A. 30%
B. 20%
C. 40%
D. 80%
Answer: A
Rationale: Chargaff’s rule states that the amount of Cytosine equals Guanine, so C+G =
40%. The remaining 60% must be shared equally between Adenine and Thymine.
Therefore, Adenine accounts for exactly 30% of the total nitrogenous bases.
Final Exam) | UCLA
1. Which property of water allows it to resist drastic temperature changes and maintain
homeostasis in organisms?
A. Low surface tension
B. Non-polar covalent bonding
C. High specific heat
D. High density as a solid
Answer: C
Rationale: Water’s high specific heat is due to the energy required to break hydrogen
bonds before molecules can move faster. This allows large bodies of water to stabilize
climate and organisms to maintain internal temperature. This property is vital for
metabolic processes to occur within narrow thermal ranges.
2. In the tertiary structure of a protein, which type of interaction is typically responsible for
forming disulfide bridges?
A. Ionic bonding
B. Hydrogen bonding between the backbone
C. Covalent bonding between cysteine residues
D. Hydrophobic interactions
Answer: C
Rationale: Disulfide bridges are strong covalent bonds formed between the sulfur atoms of
two cysteine side chains. These bonds provide significant stability to the protein’s overall
three-dimensional shape. They are much stronger than hydrogen or ionic interactions
found in other structural levels.
3. Which organelle is responsible for the synthesis of lipids and the detoxification of poisons?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
,Rationale: The smooth endoplasmic reticulum lacks ribosomes and specializes in lipid
synthesis and carbohydrate metabolism. It also plays a critical role in detoxifying drugs and
poisons, especially in liver cells. This contrasts with the rough ER, which focuses primarily
on protein synthesis.
4. According to the Fluid Mosaic Model, what prevents phospholipids from packing too tightly
at low temperatures?
A. Saturated fatty acids
B. Integral proteins
C. Peripheral proteins
D. Cholesterol
Answer: D
Rationale: Cholesterol acts as a fluidity buffer within the plasma membrane by hindering
the close packing of phospholipids. At low temperatures, it prevents solidification by
maintaining space between the lipids. Conversely, it reduces fluidity at high temperatures
by restricting movement.
5. A cell is placed in a solution where the solute concentration is higher than inside the cell.
The solution is:
A. Hypertonic
B. Isotonic
C. Hypotonic
D. None of the above
Answer: A
Rationale: A hypertonic solution has a higher concentration of non-penetrating solutes
compared to the cell’s interior. This causes water to leave the cell via osmosis, leading to
cell shrinkage or plasmolysis. Understanding tonicity is essential for grasping how cells
manage water balance.
6. Which molecule acts as the final electron acceptor in aerobic cellular respiration?
A. NAD+
B. FAD
C. Oxygen
D. Water
Answer: C
, Rationale: In the electron transport chain, oxygen accepts low-energy electrons and
combines with hydrogen ions to form water. This step is crucial because it allows the chain
to continue functioning by removing electrons. Without oxygen, the production of ATP via
oxidative phosphorylation would cease.
7. During glycolysis, what is the net gain of ATP per molecule of glucose?
A. 32 ATP
B. 4 ATP
C. 2 ATP
D. 36 ATP
Answer: C
Rationale: Glycolysis requires an initial investment of 2 ATP molecules to activate glucose.
Although 4 ATP are produced by substrate-level phosphorylation, the net result is only 2
ATP. This pathway serves as the foundational metabolic step for both aerobic and
anaerobic respiration.
8. Where do the light-dependent reactions of photosynthesis take place within the
chloroplast?
A. Thylakoid membrane
B. Stroma
C. Inner membrane space
D. Outer membrane
Answer: A
Rationale: The light reactions occur in the thylakoid membranes where chlorophyll and
other pigments are located. These pigments capture solar energy to produce ATP and
NADPH. These products are then utilized in the Calvin cycle occurring in the stroma.
9. If a DNA sample contains 20% Cytosine, what percentage of the sample is Adenine?
A. 30%
B. 20%
C. 40%
D. 80%
Answer: A
Rationale: Chargaff’s rule states that the amount of Cytosine equals Guanine, so C+G =
40%. The remaining 60% must be shared equally between Adenine and Thymine.
Therefore, Adenine accounts for exactly 30% of the total nitrogenous bases.
