BIO 250 Exam 3 — Exam Questions with
Correct Answers (VerifiedAnswers) Plus
Rationales 2026 Q&A Instant Download PDF
Question 1
Which statement best describes the primary function of the cell
membrane?
A. It produces ATP for cellular activities.
B. It stores the cell's genetic information.
C. It regulates movement of substances into and out of the
cell.
D. It synthesizes proteins for secretion.
The cell membrane serves as a selectively permeable barrier
between the intracellular and extracellular environments. Its
phospholipid bilayer and membrane proteins allow the cell to
control which substances enter or leave. This regulation is
essential for maintaining homeostasis, including appropriate
concentrations of ions, nutrients, and waste products. ATP
production occurs primarily in mitochondria, DNA is stored
primarily in the nucleus of eukaryotic cells, and protein synthesis
occurs at ribosomes.
,Question 2
Which process moves molecules across a cell membrane from
an area of higher concentration to an area of lower
concentration without directly using cellular ATP?
A. Active transport
B. Passive transport
C. Endocytosis
D. Exocytosis
Passive transport uses the existing concentration gradient and
does not require direct energy expenditure by the cell. Simple
diffusion, facilitated diffusion, and osmosis are examples. Active
transport, in contrast, requires energy to move substances
against their concentration or electrochemical gradients.
Endocytosis and exocytosis involve vesicular transport and
require cellular energy.
Question 3
A red blood cell is placed in a solution that has a lower solute
concentration than the cell. What will most likely happen?
A. The cell will lose water and shrink.
B. The cell will gain water and may swell or lyse.
,C. There will be no net movement of water.
D. The cell will actively pump water out.
The surrounding solution is hypotonic relative to the red blood
cell. Water moves by osmosis toward the region with the higher
effective solute concentration, causing water to enter the cell.
Because red blood cells lack a cell wall, excessive water entry
can cause them to swell and rupture, a process called hemolysis.
An isotonic solution would produce no net water movement,
while a hypertonic solution would cause the cell to lose water
and shrink.
Question 4
Which organelle is primarily responsible for producing ATP
through aerobic cellular respiration?
A. Lysosome
B. Golgi apparatus
C. Mitochondrion
D. Ribosome
The mitochondrion is the principal site of aerobic ATP
production in eukaryotic cells. The citric acid cycle occurs in the
mitochondrial matrix, while the electron transport chain and
oxidative phosphorylation occur along the inner mitochondrial
membrane. Ribosomes synthesize proteins, lysosomes digest
, cellular materials, and the Golgi apparatus modifies, sorts, and
packages proteins and lipids.
Question 5
What is the main purpose of cellular respiration?
A. To convert ATP into glucose
B. To extract usable energy from organic molecules and
generate ATP
C. To produce DNA from amino acids
D. To eliminate all carbon dioxide from the body
Cellular respiration transfers chemical energy stored in
molecules such as glucose into ATP, which cells can use to power
cellular processes. In aerobic respiration, oxygen ultimately
serves as the terminal electron acceptor in the electron
transport chain, and carbon dioxide is produced during carbon-
removing reactions. Cellular respiration therefore connects
nutrient metabolism with the cell's immediate energy
requirements.
Question 6
During which stage of cellular respiration is most ATP
generated?
Correct Answers (VerifiedAnswers) Plus
Rationales 2026 Q&A Instant Download PDF
Question 1
Which statement best describes the primary function of the cell
membrane?
A. It produces ATP for cellular activities.
B. It stores the cell's genetic information.
C. It regulates movement of substances into and out of the
cell.
D. It synthesizes proteins for secretion.
The cell membrane serves as a selectively permeable barrier
between the intracellular and extracellular environments. Its
phospholipid bilayer and membrane proteins allow the cell to
control which substances enter or leave. This regulation is
essential for maintaining homeostasis, including appropriate
concentrations of ions, nutrients, and waste products. ATP
production occurs primarily in mitochondria, DNA is stored
primarily in the nucleus of eukaryotic cells, and protein synthesis
occurs at ribosomes.
,Question 2
Which process moves molecules across a cell membrane from
an area of higher concentration to an area of lower
concentration without directly using cellular ATP?
A. Active transport
B. Passive transport
C. Endocytosis
D. Exocytosis
Passive transport uses the existing concentration gradient and
does not require direct energy expenditure by the cell. Simple
diffusion, facilitated diffusion, and osmosis are examples. Active
transport, in contrast, requires energy to move substances
against their concentration or electrochemical gradients.
Endocytosis and exocytosis involve vesicular transport and
require cellular energy.
Question 3
A red blood cell is placed in a solution that has a lower solute
concentration than the cell. What will most likely happen?
A. The cell will lose water and shrink.
B. The cell will gain water and may swell or lyse.
,C. There will be no net movement of water.
D. The cell will actively pump water out.
The surrounding solution is hypotonic relative to the red blood
cell. Water moves by osmosis toward the region with the higher
effective solute concentration, causing water to enter the cell.
Because red blood cells lack a cell wall, excessive water entry
can cause them to swell and rupture, a process called hemolysis.
An isotonic solution would produce no net water movement,
while a hypertonic solution would cause the cell to lose water
and shrink.
Question 4
Which organelle is primarily responsible for producing ATP
through aerobic cellular respiration?
A. Lysosome
B. Golgi apparatus
C. Mitochondrion
D. Ribosome
The mitochondrion is the principal site of aerobic ATP
production in eukaryotic cells. The citric acid cycle occurs in the
mitochondrial matrix, while the electron transport chain and
oxidative phosphorylation occur along the inner mitochondrial
membrane. Ribosomes synthesize proteins, lysosomes digest
, cellular materials, and the Golgi apparatus modifies, sorts, and
packages proteins and lipids.
Question 5
What is the main purpose of cellular respiration?
A. To convert ATP into glucose
B. To extract usable energy from organic molecules and
generate ATP
C. To produce DNA from amino acids
D. To eliminate all carbon dioxide from the body
Cellular respiration transfers chemical energy stored in
molecules such as glucose into ATP, which cells can use to power
cellular processes. In aerobic respiration, oxygen ultimately
serves as the terminal electron acceptor in the electron
transport chain, and carbon dioxide is produced during carbon-
removing reactions. Cellular respiration therefore connects
nutrient metabolism with the cell's immediate energy
requirements.
Question 6
During which stage of cellular respiration is most ATP
generated?
