PCB 3023C Cell Biology Final Exam
Questions & Answers | Grade A | 100%
Correct
1. Which organelle is primarily responsible for the synthesis of lipids and the
detoxification of drugs?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
Explanation: The Smooth Endoplasmic Reticulum is the site of lipid synthesis, including
phospholipids and steroids, and contains enzymes that detoxify harmful substances.
2. What is the primary function of the nucleolus?
A. DNA Replication
B. mRNA Splicing
C. Ribosomal RNA synthesis and ribosome assembly
D. Protein folding
Answer: C
Explanation: The nucleolus is a dense region within the nucleus where rRNA is
transcribed and combined with proteins to form ribosomal subunits.
,3. In the fluid mosaic model, what is the role of cholesterol in the plasma
membrane?
A. It acts as a transport channel.
B. It regulates membrane fluidity at different temperatures.
C. It functions as a cell recognition marker.
D. It triggers signal transduction.
Answer: B
Explanation: Cholesterol prevents the membrane from becoming too fluid at high
temperatures and too rigid at low temperatures.
4. Which molecule acts as the final electron acceptor in the mitochondrial
electron transport chain?
A. Oxygen
B. FAD
C. Water
D. NAD+
Answer: A
Explanation: In aerobic respiration, oxygen is the final electron acceptor, combining with
electrons and protons to form water.
5. Which of the following describes a ‘hypotonic’ environment for a typical
animal cell?
A. The solute concentration outside is lower than inside.
B. The solute concentration outside is higher than inside.
C. The solute concentration is equal on both sides.
D. There is no movement of water across the membrane.
Answer: A
Explanation: In a hypotonic solution, the lower external solute concentration causes water
to enter the cell by osmosis, potentially leading to lysis.
, 6. Which cytoskeletal filament is composed of actin and is involved in muscle
contraction?
A. Microfilaments
B. Intermediate Filaments
C. Microtubules
D. Keratin filaments
Answer: A
Explanation: Microfilaments are made of actin monomers and work with myosin to
facilitate cell movement and muscle contraction.
7. What is the role of the Golgi apparatus in the cell?
A. ATP production
B. Digestion of cellular waste
C. Modifying, sorting, and packaging proteins
D. Synthesis of glucose
Answer: C
Explanation: The Golgi apparatus receives proteins from the ER, modifies them (e.g.,
glycosylation), and sorts them for transport to their final destinations.
8. During which phase of the cell cycle is DNA replicated?
A. G1 phase
B. M phase
C. G2 phase
D. S phase
Answer: D
Explanation: The S (Synthesis) phase is the specific period during interphase when the cell
replicates its genomic DNA.
Questions & Answers | Grade A | 100%
Correct
1. Which organelle is primarily responsible for the synthesis of lipids and the
detoxification of drugs?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
Explanation: The Smooth Endoplasmic Reticulum is the site of lipid synthesis, including
phospholipids and steroids, and contains enzymes that detoxify harmful substances.
2. What is the primary function of the nucleolus?
A. DNA Replication
B. mRNA Splicing
C. Ribosomal RNA synthesis and ribosome assembly
D. Protein folding
Answer: C
Explanation: The nucleolus is a dense region within the nucleus where rRNA is
transcribed and combined with proteins to form ribosomal subunits.
,3. In the fluid mosaic model, what is the role of cholesterol in the plasma
membrane?
A. It acts as a transport channel.
B. It regulates membrane fluidity at different temperatures.
C. It functions as a cell recognition marker.
D. It triggers signal transduction.
Answer: B
Explanation: Cholesterol prevents the membrane from becoming too fluid at high
temperatures and too rigid at low temperatures.
4. Which molecule acts as the final electron acceptor in the mitochondrial
electron transport chain?
A. Oxygen
B. FAD
C. Water
D. NAD+
Answer: A
Explanation: In aerobic respiration, oxygen is the final electron acceptor, combining with
electrons and protons to form water.
5. Which of the following describes a ‘hypotonic’ environment for a typical
animal cell?
A. The solute concentration outside is lower than inside.
B. The solute concentration outside is higher than inside.
C. The solute concentration is equal on both sides.
D. There is no movement of water across the membrane.
Answer: A
Explanation: In a hypotonic solution, the lower external solute concentration causes water
to enter the cell by osmosis, potentially leading to lysis.
, 6. Which cytoskeletal filament is composed of actin and is involved in muscle
contraction?
A. Microfilaments
B. Intermediate Filaments
C. Microtubules
D. Keratin filaments
Answer: A
Explanation: Microfilaments are made of actin monomers and work with myosin to
facilitate cell movement and muscle contraction.
7. What is the role of the Golgi apparatus in the cell?
A. ATP production
B. Digestion of cellular waste
C. Modifying, sorting, and packaging proteins
D. Synthesis of glucose
Answer: C
Explanation: The Golgi apparatus receives proteins from the ER, modifies them (e.g.,
glycosylation), and sorts them for transport to their final destinations.
8. During which phase of the cell cycle is DNA replicated?
A. G1 phase
B. M phase
C. G2 phase
D. S phase
Answer: D
Explanation: The S (Synthesis) phase is the specific period during interphase when the cell
replicates its genomic DNA.
