HESI A2 Biology Exam
2025/2026 – Verified
Questions & Correct Answers
| Updated Real Exam
Cellular Structure and Function (Questions 1-30)
1. Question: What is the primary function of the cell membrane? Options:
o A. Protein synthesis
o B. Selective permeability
o C. Energy production
o D. DNA storage Answer: B. Selective permeability Rationale: The phospholipid
bilayer regulates entry/exit of substances, maintaining cellular homeostasis via
passive and active transport processes.
2. Question: Which organelle is known as the "powerhouse" of the cell? Options:
o A. Nucleus
o B. Mitochondria
o C. Ribosome
o D. Golgi apparatus Answer: B. Mitochondria Rationale: Mitochondria generate
ATP through cellular respiration, providing energy for cellular processes.
3. Question: Prokaryotic cells differ from eukaryotic cells by lacking? Options:
o A. Cell wall
o B. Nucleus
o C. Ribosomes
o D. Cytoplasm Answer: B. Nucleus Rationale: Prokaryotes have DNA in
nucleoid region; eukaryotes enclose DNA in nucleus for organized genetic
control.
4. Question: The fluid mosaic model describes the cell membrane as? Options:
o A. Rigid structure
o B. Dynamic with embedded proteins
o C. Static lipid layer
o D. Carbohydrate barrier Answer: B. Dynamic with embedded proteins
Rationale: Proteins and lipids move laterally, enabling transport, signaling, and
flexibility in cellular interactions.
5. Question: Which structure synthesizes proteins? Options:
o A. Lysosome
o B. Ribosome
o C. Endoplasmic reticulum
, o D. Vacuole Answer: B. Ribosome Rationale: Ribosomes translate mRNA into
polypeptides, essential for protein synthesis in cellular function.
6. Question: What is the role of lysosomes? Options:
o A. Lipid synthesis
o B. Intracellular digestion
o C. Photosynthesis
o D. Calcium storage Answer: B. Intracellular digestion Rationale: Lysosomes
contain hydrolytic enzymes breaking down waste, maintaining cellular
homeostasis.
7. Question: The rough endoplasmic reticulum is studded with? Options:
o A. Mitochondria
o B. Ribosomes
o C. Chloroplasts
o D. Cilia Answer: B. Ribosomes Rationale: RER facilitates protein folding and
modification post-translation for secretory pathways.
8. Question: Which is a function of the Golgi apparatus? Options:
o A. DNA replication
o B. Protein packaging
o C. ATP synthesis
o D. Cell division Answer: B. Protein packaging Rationale: Golgi modifies, sorts,
and packages proteins/lipids into vesicles for transport.
9. Question: Centrioles are involved in? Options:
o A. Cell motility
o B. Mitotic spindle formation
o C. Lipid transport
o D. Waste removal Answer: B. Mitotic spindle formation Rationale: Centrioles
organize microtubules during mitosis, ensuring accurate chromosome segregation.
10. Question: The nucleolus is responsible for? Options:
o A. rRNA synthesis
o B. DNA storage
o C. Protein degradation
o D. Energy conversion Answer: A. rRNA synthesis Rationale: Nucleolus
assembles ribosomal subunits, critical for translation in protein synthesis.
11. Question: Passive transport requires? Options:
o A. Energy input
o B. Concentration gradient
o C. Carrier proteins only
o D. ATP hydrolysis Answer: B. Concentration gradient Rationale:
Diffusion/osmosis moves molecules down gradient, conserving energy in cellular
membranes.
12. Question: Active transport is exemplified by? Options:
o A. Simple diffusion
o B. Sodium-potassium pump
o C. Facilitated diffusion
o D. Osmosis Answer: B. Sodium-potassium pump Rationale: Uses ATP to move
ions against gradient, maintaining membrane potential in cellular signaling.
, 13. Question: Endocytosis involves? Options:
o A. Exocytosis
o B. Engulfing materials
o C. Pinching off membrane
o D. Channel proteins Answer: B. Engulfing materials Rationale:
Phagocytosis/pinocytosis imports large particles, essential for nutrient uptake in
cells.
14. Question: What maintains cell shape? Options:
o A. Cytoskeleton
o B. Nucleus
o C. Plasma membrane
o D. Vacuoles Answer: A. Cytoskeleton Rationale: Microtubules, actin,
intermediate filaments provide structural support and motility.
15. Question: Chloroplasts are found in? Options:
o A. Animal cells
o B. Plant cells
o C. Bacterial cells
o D. Fungal cells Answer: B. Plant cells Rationale: Contain thylakoids for
photosynthesis, converting light to chemical energy in plants.
16. Question: The cell wall in plants provides? Options:
o A. Flexibility
o B. Rigid support
o C. Permeability
o D. Energy Answer: B. Rigid support Rationale: Cellulose matrix protects against
osmotic pressure, maintaining turgor in plant cells.
17. Question: Facilitated diffusion uses? Options:
o A. ATP
o B. Channel proteins
o C. Vesicles
o D. Pumps Answer: B. Channel proteins Rationale: Proteins aid polar molecules
across hydrophobic membrane without energy.
18. Question: Osmosis is the movement of? Options:
o A. Solutes
o B. Water
o C. Proteins
o D. Gases Answer: B. Water Rationale: Water diffuses across semi-permeable
membrane toward hypertonic side, balancing solutions.
19. Question: Hypertonic solution causes cells to? Options:
o A. Swell
o B. Shrink
o C. Burst
o D. Divide Answer: B. Shrink Rationale: Water exits cell via osmosis, leading to
crenation in animal cells or plasmolysis in plants.
20. Question: Isotonic solution means? Options:
o A. Equal solute concentration
o B. High solute outside
2025/2026 – Verified
Questions & Correct Answers
| Updated Real Exam
Cellular Structure and Function (Questions 1-30)
1. Question: What is the primary function of the cell membrane? Options:
o A. Protein synthesis
o B. Selective permeability
o C. Energy production
o D. DNA storage Answer: B. Selective permeability Rationale: The phospholipid
bilayer regulates entry/exit of substances, maintaining cellular homeostasis via
passive and active transport processes.
2. Question: Which organelle is known as the "powerhouse" of the cell? Options:
o A. Nucleus
o B. Mitochondria
o C. Ribosome
o D. Golgi apparatus Answer: B. Mitochondria Rationale: Mitochondria generate
ATP through cellular respiration, providing energy for cellular processes.
3. Question: Prokaryotic cells differ from eukaryotic cells by lacking? Options:
o A. Cell wall
o B. Nucleus
o C. Ribosomes
o D. Cytoplasm Answer: B. Nucleus Rationale: Prokaryotes have DNA in
nucleoid region; eukaryotes enclose DNA in nucleus for organized genetic
control.
4. Question: The fluid mosaic model describes the cell membrane as? Options:
o A. Rigid structure
o B. Dynamic with embedded proteins
o C. Static lipid layer
o D. Carbohydrate barrier Answer: B. Dynamic with embedded proteins
Rationale: Proteins and lipids move laterally, enabling transport, signaling, and
flexibility in cellular interactions.
5. Question: Which structure synthesizes proteins? Options:
o A. Lysosome
o B. Ribosome
o C. Endoplasmic reticulum
, o D. Vacuole Answer: B. Ribosome Rationale: Ribosomes translate mRNA into
polypeptides, essential for protein synthesis in cellular function.
6. Question: What is the role of lysosomes? Options:
o A. Lipid synthesis
o B. Intracellular digestion
o C. Photosynthesis
o D. Calcium storage Answer: B. Intracellular digestion Rationale: Lysosomes
contain hydrolytic enzymes breaking down waste, maintaining cellular
homeostasis.
7. Question: The rough endoplasmic reticulum is studded with? Options:
o A. Mitochondria
o B. Ribosomes
o C. Chloroplasts
o D. Cilia Answer: B. Ribosomes Rationale: RER facilitates protein folding and
modification post-translation for secretory pathways.
8. Question: Which is a function of the Golgi apparatus? Options:
o A. DNA replication
o B. Protein packaging
o C. ATP synthesis
o D. Cell division Answer: B. Protein packaging Rationale: Golgi modifies, sorts,
and packages proteins/lipids into vesicles for transport.
9. Question: Centrioles are involved in? Options:
o A. Cell motility
o B. Mitotic spindle formation
o C. Lipid transport
o D. Waste removal Answer: B. Mitotic spindle formation Rationale: Centrioles
organize microtubules during mitosis, ensuring accurate chromosome segregation.
10. Question: The nucleolus is responsible for? Options:
o A. rRNA synthesis
o B. DNA storage
o C. Protein degradation
o D. Energy conversion Answer: A. rRNA synthesis Rationale: Nucleolus
assembles ribosomal subunits, critical for translation in protein synthesis.
11. Question: Passive transport requires? Options:
o A. Energy input
o B. Concentration gradient
o C. Carrier proteins only
o D. ATP hydrolysis Answer: B. Concentration gradient Rationale:
Diffusion/osmosis moves molecules down gradient, conserving energy in cellular
membranes.
12. Question: Active transport is exemplified by? Options:
o A. Simple diffusion
o B. Sodium-potassium pump
o C. Facilitated diffusion
o D. Osmosis Answer: B. Sodium-potassium pump Rationale: Uses ATP to move
ions against gradient, maintaining membrane potential in cellular signaling.
, 13. Question: Endocytosis involves? Options:
o A. Exocytosis
o B. Engulfing materials
o C. Pinching off membrane
o D. Channel proteins Answer: B. Engulfing materials Rationale:
Phagocytosis/pinocytosis imports large particles, essential for nutrient uptake in
cells.
14. Question: What maintains cell shape? Options:
o A. Cytoskeleton
o B. Nucleus
o C. Plasma membrane
o D. Vacuoles Answer: A. Cytoskeleton Rationale: Microtubules, actin,
intermediate filaments provide structural support and motility.
15. Question: Chloroplasts are found in? Options:
o A. Animal cells
o B. Plant cells
o C. Bacterial cells
o D. Fungal cells Answer: B. Plant cells Rationale: Contain thylakoids for
photosynthesis, converting light to chemical energy in plants.
16. Question: The cell wall in plants provides? Options:
o A. Flexibility
o B. Rigid support
o C. Permeability
o D. Energy Answer: B. Rigid support Rationale: Cellulose matrix protects against
osmotic pressure, maintaining turgor in plant cells.
17. Question: Facilitated diffusion uses? Options:
o A. ATP
o B. Channel proteins
o C. Vesicles
o D. Pumps Answer: B. Channel proteins Rationale: Proteins aid polar molecules
across hydrophobic membrane without energy.
18. Question: Osmosis is the movement of? Options:
o A. Solutes
o B. Water
o C. Proteins
o D. Gases Answer: B. Water Rationale: Water diffuses across semi-permeable
membrane toward hypertonic side, balancing solutions.
19. Question: Hypertonic solution causes cells to? Options:
o A. Swell
o B. Shrink
o C. Burst
o D. Divide Answer: B. Shrink Rationale: Water exits cell via osmosis, leading to
crenation in animal cells or plasmolysis in plants.
20. Question: Isotonic solution means? Options:
o A. Equal solute concentration
o B. High solute outside
