Biology Breakdown for HESI A2 2024/2025
100% Verified Questions with Concept-Based Explanations
Prepared for HESI A2 Exam Preparation
June 06, 2025
Contents
1 Cell Biology 2
2 DNA and Genetics 7
3 Physiology 11
4 Human Systems 16
1
,1 Cell Biology
1. Which organelle is primarily responsible for detoxifying harmful substances in a
liver cell?
A. Mitochondrion
B. Smooth Endoplasmic Reticulum
C. Golgi Apparatus
D. Lysosome
Answer: B. Smooth Endoplasmic Reticulum Explanation: The smooth endo-
plasmic reticulum (SER) is crucial in liver cells for detoxifying drugs, alcohol, and
other toxins by enzymatic modification, making them water-soluble for excretion.
Mitochondria produce energy, the Golgi apparatus modifies proteins, and lysosomes
degrade waste.
2. What is the primary source of energy for a cell during anaerobic conditions?
A. Glucose
B. Lactic Acid
C. ATP
D. Oxygen
Answer: A. Glucose Explanation: In anaerobic conditions, cells rely on glycol-
ysis, which breaks down glucose to produce ATP without oxygen. Lactic acid is
a byproduct in some cells, ATP is the energy currency, and oxygen is absent in
anaerobic processes.
3. How does the structure of the plasma membrane contribute to selective permeabil-
ity?
A. Protein channels block all molecules
B. Phospholipid bilayer allows only nonpolar molecules to pass
C. Cholesterol prevents all diffusion
D. Carrier proteins facilitate specific molecule transport
Answer: D. Carrier proteins facilitate specific molecule transport Explanation:
The plasma membranes phospholipid bilayer allows small, nonpolar molecules to
pass, but carrier proteins enable selective transport of specific polar or large molecules,
ensuring controlled exchange. Other options misrepresent membrane functions.
4. What role do ribosomes play in a eukaryotic cell?
A. DNA replication
B. Protein synthesis
C. Lipid production
D. Energy storage
2
, Answer: B. Protein synthesis Explanation: Ribosomes translate mRNA into
proteins, a critical process for cell function and structure. DNA replication occurs
in the nucleus, lipids are made in the ER, and energy is stored as ATP or glycogen.
5. Which process allows a white blood cell to engulf a bacterium?
A. Osmosis
B. Phagocytosis
C. Pinocytosis
D. Diffusion
Answer: B. Phagocytosis Explanation: Phagocytosis is the process by which
cells like white blood cells engulf large particles, such as bacteria, to destroy them.
Osmosis and diffusion involve small molecules, and pinocytosis engulfs fluids, not
solids.
6. What is the primary function of the nucleolus within the nucleus?
A. DNA storage
B. Ribosomal RNA synthesis
C. Protein degradation
D. Cell division regulation
Answer: B. Ribosomal RNA synthesis Explanation: The nucleolus assembles
ribosomal RNA (rRNA) and combines it with proteins to form ribosomes. DNA is
stored throughout the nucleus, proteins are degraded by lysosomes, and cell division
is regulated by other nuclear components.
7. How does active transport differ from passive transport?
A. Active transport requires energy, passive does not
B. Passive transport uses ATP, active does not
C. Active transport occurs only in plant cells
D. Passive transport moves molecules against a gradient
Answer: A. Active transport requires energy, passive does not Explanation:
Active transport uses ATP to move molecules against their concentration gradient,
while passive transport relies on diffusion down the gradient, requiring no energy.
Other options are incorrect.
8. What structure in a plant cell provides rigidity and support?
A. Cell membrane
B. Cell wall
C. Cytoplasm
D. Vacuole
3
100% Verified Questions with Concept-Based Explanations
Prepared for HESI A2 Exam Preparation
June 06, 2025
Contents
1 Cell Biology 2
2 DNA and Genetics 7
3 Physiology 11
4 Human Systems 16
1
,1 Cell Biology
1. Which organelle is primarily responsible for detoxifying harmful substances in a
liver cell?
A. Mitochondrion
B. Smooth Endoplasmic Reticulum
C. Golgi Apparatus
D. Lysosome
Answer: B. Smooth Endoplasmic Reticulum Explanation: The smooth endo-
plasmic reticulum (SER) is crucial in liver cells for detoxifying drugs, alcohol, and
other toxins by enzymatic modification, making them water-soluble for excretion.
Mitochondria produce energy, the Golgi apparatus modifies proteins, and lysosomes
degrade waste.
2. What is the primary source of energy for a cell during anaerobic conditions?
A. Glucose
B. Lactic Acid
C. ATP
D. Oxygen
Answer: A. Glucose Explanation: In anaerobic conditions, cells rely on glycol-
ysis, which breaks down glucose to produce ATP without oxygen. Lactic acid is
a byproduct in some cells, ATP is the energy currency, and oxygen is absent in
anaerobic processes.
3. How does the structure of the plasma membrane contribute to selective permeabil-
ity?
A. Protein channels block all molecules
B. Phospholipid bilayer allows only nonpolar molecules to pass
C. Cholesterol prevents all diffusion
D. Carrier proteins facilitate specific molecule transport
Answer: D. Carrier proteins facilitate specific molecule transport Explanation:
The plasma membranes phospholipid bilayer allows small, nonpolar molecules to
pass, but carrier proteins enable selective transport of specific polar or large molecules,
ensuring controlled exchange. Other options misrepresent membrane functions.
4. What role do ribosomes play in a eukaryotic cell?
A. DNA replication
B. Protein synthesis
C. Lipid production
D. Energy storage
2
, Answer: B. Protein synthesis Explanation: Ribosomes translate mRNA into
proteins, a critical process for cell function and structure. DNA replication occurs
in the nucleus, lipids are made in the ER, and energy is stored as ATP or glycogen.
5. Which process allows a white blood cell to engulf a bacterium?
A. Osmosis
B. Phagocytosis
C. Pinocytosis
D. Diffusion
Answer: B. Phagocytosis Explanation: Phagocytosis is the process by which
cells like white blood cells engulf large particles, such as bacteria, to destroy them.
Osmosis and diffusion involve small molecules, and pinocytosis engulfs fluids, not
solids.
6. What is the primary function of the nucleolus within the nucleus?
A. DNA storage
B. Ribosomal RNA synthesis
C. Protein degradation
D. Cell division regulation
Answer: B. Ribosomal RNA synthesis Explanation: The nucleolus assembles
ribosomal RNA (rRNA) and combines it with proteins to form ribosomes. DNA is
stored throughout the nucleus, proteins are degraded by lysosomes, and cell division
is regulated by other nuclear components.
7. How does active transport differ from passive transport?
A. Active transport requires energy, passive does not
B. Passive transport uses ATP, active does not
C. Active transport occurs only in plant cells
D. Passive transport moves molecules against a gradient
Answer: A. Active transport requires energy, passive does not Explanation:
Active transport uses ATP to move molecules against their concentration gradient,
while passive transport relies on diffusion down the gradient, requiring no energy.
Other options are incorrect.
8. What structure in a plant cell provides rigidity and support?
A. Cell membrane
B. Cell wall
C. Cytoplasm
D. Vacuole
3
