Hesi A2 Biology LATEST VERSION 2026-2027 EXAM WITH
ACTUAL 180 QUESTION AND CORRECT DETAILED ANSWERS
WITH RATIONALES.RATED FIVE STARS.,,, (MOST TESTED
QUESTIONS)
QUESTION
Which type of nucleic acid is responsible for carrying the genetic code from the nucleus
to the ribosome in the cytoplasm, where protein synthesis occurs?
CORRECT ANS: Messenger RNA (mRNA) carries information about a protein sequence
to the ribosomes, the protein synthesis factories in the cell. It is coded so that every
three nucleotides (a codon) correspond to one amino acid.
EXPERT RATIONALE
Messenger RNA (mRNA) is a single-stranded RNA molecule that serves as the
intermediary between DNA and protein synthesis. During transcription, mRNA is
synthesized from a DNA template in the nucleus. This mRNA molecule then exits the
nucleus through nuclear pores and travels to the ribosome in the cytoplasm, where its
nucleotide sequence is translated into a specific amino acid sequence. The genetic code
is read in triplets called codons, each specifying a particular amino acid. Transfer RNA
(tRNA) and ribosomal RNA (rRNA) are also involved in protein synthesis but do not carry
the genetic code from the nucleus. tRNA transports amino acids to the ribosome, and
rRNA is a structural component of the ribosome.
QUESTION
What is the process by which a prokaryotic cell divides into two identical daughter cells?
CORRECT ANS: In this process, the chromosome binds to the cell membrane, where it
replicates. As the cell grows, it pinches in two, producing two identical cells.
EXPERT RATIONALE
Binary fission is the primary method of asexual reproduction in prokaryotic organisms,
such as bacteria and archaea. The process begins with the replication of the single,
circular bacterial chromosome, which attaches to the cell membrane. As the cell
elongates, the two replicated chromosomes are pulled apart. A new cell wall and plasma
membrane then form, pinching the cell inward (a process called cytokinesis) and
,dividing it into two genetically identical daughter cells. This is a rapid and efficient
means of reproduction. This is distinct from mitosis, which occurs in eukaryotic cells and
involves a more complex division of the nucleus.
QUESTION
What is the structure within a cell that contains all the DNA material necessary for the
cell's regeneration and provides the instructions for the cell's function?
CORRECT ANS: Contains all the DNA material necessary for the regeneration of the cell,
as well as all instructions for the function of the cell. Every organism has a characteristic
number of chromosomes specific to the particular species.
EXPERT RATIONALE
Chromosomes are thread-like structures located within the nucleus of eukaryotic cells.
They are composed of DNA tightly coiled around proteins called histones. This DNA
contains the organism's entire genome, which consists of all the genes and non-coding
sequences. The genetic information encoded in chromosomes is essential for the cell's
growth, metabolism, reproduction, and response to its environment. Each species has a
characteristic and constant number of chromosomes in its somatic cells. For example,
humans have 46 chromosomes (23 pairs), which is a defining feature of the species.
QUESTION
Which statement correctly describes a difference between the cytosol and the
mitochondrion?
a. Mitochondrion is a membrane-bounded cell organelle while cytosol lacks any
definitive membranous outer covering.
b. Cytosol is a membrane-bounded organelle while the mitochondrion lacks any
definitive membranous outer covering.
c. Both the cytosol and the mitochondrion are membrane-bounded organelles.
d. Neither the cytosol nor the mitochondrion has a definitive membranous outer
covering.
,CORRECT ANS: a. Mitochondrion which is also known as the power house of the cell is
a membrane-bounded cell organelle while cytosol lacks any definitive membranous
outer covering.
EXPERT RATIONALE
The mitochondrion is a double-membrane-bound organelle found in eukaryotic cells. It
is composed of an outer membrane and a highly folded inner membrane (cristae) that
encloses the mitochondrial matrix. This organelle is the site of aerobic cellular
respiration and ATP production. In contrast, the cytosol is the aqueous, semi-fluid
component of the cytoplasm that surrounds the organelles. It is not a membrane-bound
organelle; rather, it is the internal fluid of the cell in which the organelles are suspended.
The cytosol contains dissolved ions, proteins, and other molecules.
QUESTION
What is the fluid in which the organelles of the cell reside?
CORRECT ANS: The cytosol is the fluid in which organelles of the cell reside. This is
often confused with cytoplasm, which is the space between the nucleus and the plasma
membrane.
EXPERT RATIONALE
The cytosol is the intracellular fluid, the liquid portion of the cytoplasm that is not
contained within organelles. It is a complex mixture of water, salts, organic molecules,
and dissolved proteins. The cytosol is the site of many metabolic reactions and provides
a medium for the suspension and transport of organelles. It is important to distinguish
the cytosol from the cytoplasm, which is the entire region between the nucleus and the
cell membrane, including the cytosol and the organelles.
QUESTION
Which of the following processes does NOT lead to cellular energy production?
a. Glycolysis
b. Krebs cycle
c. Electron transport chain
d. Gluconeogenesis
, CORRECT ANS: Gluconeogenesis is a metabolic pathway that results in the generation
of glucose from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol,
and glucogenic amino acids. This process requires energy.
EXPERT RATIONALE
Gluconeogenesis is a metabolic pathway that synthesizes glucose from non-
carbohydrate precursors. This is a critical process for maintaining blood glucose levels,
especially during fasting or starvation. However, it is an anabolic (building) pathway that
consumes ATP rather than producing it. The other processes—glycolysis, the Krebs
cycle, and the electron transport chain—are all catabolic pathways involved in cellular
respiration that generate ATP. Glycolysis breaks down glucose and yields a net gain of 2
ATP; the Krebs cycle yields GTP and electron carriers; and the electron transport chain
generates the majority of ATP.
QUESTION
What is the division of cytoplasm known as?
CORRECT ANS: The division of cytoplasm is known as cytokinesis. This stage begins
when the mitosis is near completion and results in the formation of two daughter cells.
EXPERT RATIONALE
Cytokinesis is the final stage of the cell cycle, during which the cytoplasm of a single
eukaryotic cell divides into two daughter cells. It occurs concurrently with the final
stages of nuclear division (mitosis or meiosis). In animal cells, cytokinesis is achieved by
the formation of a cleavage furrow that pinches the cell in two. In plant cells, a cell plate
forms to divide the cytoplasm and is then reinforced to become a new cell wall.
Cytokinesis is essential for producing two separate, functional cells.
QUESTION
ATP is able to power cellular work by undergoing a certain reaction. Which of these
chemical equations best represents this reaction?
a. ATP + H₂O → ADP + Pi + Energy
b. ATP + Energy → ADP + Pi + H₂O
ACTUAL 180 QUESTION AND CORRECT DETAILED ANSWERS
WITH RATIONALES.RATED FIVE STARS.,,, (MOST TESTED
QUESTIONS)
QUESTION
Which type of nucleic acid is responsible for carrying the genetic code from the nucleus
to the ribosome in the cytoplasm, where protein synthesis occurs?
CORRECT ANS: Messenger RNA (mRNA) carries information about a protein sequence
to the ribosomes, the protein synthesis factories in the cell. It is coded so that every
three nucleotides (a codon) correspond to one amino acid.
EXPERT RATIONALE
Messenger RNA (mRNA) is a single-stranded RNA molecule that serves as the
intermediary between DNA and protein synthesis. During transcription, mRNA is
synthesized from a DNA template in the nucleus. This mRNA molecule then exits the
nucleus through nuclear pores and travels to the ribosome in the cytoplasm, where its
nucleotide sequence is translated into a specific amino acid sequence. The genetic code
is read in triplets called codons, each specifying a particular amino acid. Transfer RNA
(tRNA) and ribosomal RNA (rRNA) are also involved in protein synthesis but do not carry
the genetic code from the nucleus. tRNA transports amino acids to the ribosome, and
rRNA is a structural component of the ribosome.
QUESTION
What is the process by which a prokaryotic cell divides into two identical daughter cells?
CORRECT ANS: In this process, the chromosome binds to the cell membrane, where it
replicates. As the cell grows, it pinches in two, producing two identical cells.
EXPERT RATIONALE
Binary fission is the primary method of asexual reproduction in prokaryotic organisms,
such as bacteria and archaea. The process begins with the replication of the single,
circular bacterial chromosome, which attaches to the cell membrane. As the cell
elongates, the two replicated chromosomes are pulled apart. A new cell wall and plasma
membrane then form, pinching the cell inward (a process called cytokinesis) and
,dividing it into two genetically identical daughter cells. This is a rapid and efficient
means of reproduction. This is distinct from mitosis, which occurs in eukaryotic cells and
involves a more complex division of the nucleus.
QUESTION
What is the structure within a cell that contains all the DNA material necessary for the
cell's regeneration and provides the instructions for the cell's function?
CORRECT ANS: Contains all the DNA material necessary for the regeneration of the cell,
as well as all instructions for the function of the cell. Every organism has a characteristic
number of chromosomes specific to the particular species.
EXPERT RATIONALE
Chromosomes are thread-like structures located within the nucleus of eukaryotic cells.
They are composed of DNA tightly coiled around proteins called histones. This DNA
contains the organism's entire genome, which consists of all the genes and non-coding
sequences. The genetic information encoded in chromosomes is essential for the cell's
growth, metabolism, reproduction, and response to its environment. Each species has a
characteristic and constant number of chromosomes in its somatic cells. For example,
humans have 46 chromosomes (23 pairs), which is a defining feature of the species.
QUESTION
Which statement correctly describes a difference between the cytosol and the
mitochondrion?
a. Mitochondrion is a membrane-bounded cell organelle while cytosol lacks any
definitive membranous outer covering.
b. Cytosol is a membrane-bounded organelle while the mitochondrion lacks any
definitive membranous outer covering.
c. Both the cytosol and the mitochondrion are membrane-bounded organelles.
d. Neither the cytosol nor the mitochondrion has a definitive membranous outer
covering.
,CORRECT ANS: a. Mitochondrion which is also known as the power house of the cell is
a membrane-bounded cell organelle while cytosol lacks any definitive membranous
outer covering.
EXPERT RATIONALE
The mitochondrion is a double-membrane-bound organelle found in eukaryotic cells. It
is composed of an outer membrane and a highly folded inner membrane (cristae) that
encloses the mitochondrial matrix. This organelle is the site of aerobic cellular
respiration and ATP production. In contrast, the cytosol is the aqueous, semi-fluid
component of the cytoplasm that surrounds the organelles. It is not a membrane-bound
organelle; rather, it is the internal fluid of the cell in which the organelles are suspended.
The cytosol contains dissolved ions, proteins, and other molecules.
QUESTION
What is the fluid in which the organelles of the cell reside?
CORRECT ANS: The cytosol is the fluid in which organelles of the cell reside. This is
often confused with cytoplasm, which is the space between the nucleus and the plasma
membrane.
EXPERT RATIONALE
The cytosol is the intracellular fluid, the liquid portion of the cytoplasm that is not
contained within organelles. It is a complex mixture of water, salts, organic molecules,
and dissolved proteins. The cytosol is the site of many metabolic reactions and provides
a medium for the suspension and transport of organelles. It is important to distinguish
the cytosol from the cytoplasm, which is the entire region between the nucleus and the
cell membrane, including the cytosol and the organelles.
QUESTION
Which of the following processes does NOT lead to cellular energy production?
a. Glycolysis
b. Krebs cycle
c. Electron transport chain
d. Gluconeogenesis
, CORRECT ANS: Gluconeogenesis is a metabolic pathway that results in the generation
of glucose from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol,
and glucogenic amino acids. This process requires energy.
EXPERT RATIONALE
Gluconeogenesis is a metabolic pathway that synthesizes glucose from non-
carbohydrate precursors. This is a critical process for maintaining blood glucose levels,
especially during fasting or starvation. However, it is an anabolic (building) pathway that
consumes ATP rather than producing it. The other processes—glycolysis, the Krebs
cycle, and the electron transport chain—are all catabolic pathways involved in cellular
respiration that generate ATP. Glycolysis breaks down glucose and yields a net gain of 2
ATP; the Krebs cycle yields GTP and electron carriers; and the electron transport chain
generates the majority of ATP.
QUESTION
What is the division of cytoplasm known as?
CORRECT ANS: The division of cytoplasm is known as cytokinesis. This stage begins
when the mitosis is near completion and results in the formation of two daughter cells.
EXPERT RATIONALE
Cytokinesis is the final stage of the cell cycle, during which the cytoplasm of a single
eukaryotic cell divides into two daughter cells. It occurs concurrently with the final
stages of nuclear division (mitosis or meiosis). In animal cells, cytokinesis is achieved by
the formation of a cleavage furrow that pinches the cell in two. In plant cells, a cell plate
forms to divide the cytoplasm and is then reinforced to become a new cell wall.
Cytokinesis is essential for producing two separate, functional cells.
QUESTION
ATP is able to power cellular work by undergoing a certain reaction. Which of these
chemical equations best represents this reaction?
a. ATP + H₂O → ADP + Pi + Energy
b. ATP + Energy → ADP + Pi + H₂O
