[ASU BIO181 GENERAL BIOLOGY 2026] – EXAM-STYLE QUESTIONS AND
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS | PLUS RATIONALES |
GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP | STUDY GUIDE |
PRACTICE TEST
1. Which of the following best describes the relationship between the structure
and function of the phospholipid bilayer in a cellular membrane?
A. The hydrophilic phosphate heads face the interior of the membrane, while the
hydrophobic fatty acid tails face the aqueous environment.
B. The hydrophobic fatty acid tails form a barrier to hydrophilic molecules, while
the hydrophilic heads interact with the aqueous intracellular and extracellular
environments.
C. The phospholipids are arranged in a single layer with hydrophobic tails
interacting with the cytoskeleton to provide structural support.
D. The bilayer is static, with phospholipids remaining fixed in place to maintain
membrane rigidity and stability.
Correct Answer: B. The hydrophobic fatty acid tails form a barrier to hydrophilic
molecules, while the hydrophilic heads interact with the aqueous intracellular and
extracellular environments.
Rationale: This is the fundamental description of the phospholipid bilayer's
structure, where the hydrophobic tails face inward creating a barrier to polar
molecules and ions. The hydrophilic phosphate heads face outward, interacting with
water on both sides. Option A incorrectly describes the orientation of the heads and
tails. Option C is incorrect as the membrane is a bilayer, not a monolayer. Option D
is incorrect because the membrane is fluid, not static.
,2. During a laboratory experiment, a student observes that cells placed in a
hypertonic solution undergo plasmolysis. This observation directly supports
which conclusion about the cell membrane?
A. It is a selectively permeable barrier that allows water to move via osmosis but
prevents the passage of large solutes.
B. It is an impermeable barrier that prevents all solutes from entering or leaving
the cell.
C. It is a completely permeable membrane that allows free movement of water
and solutes.
D. It is a rigid structure that maintains cell shape regardless of external osmotic
conditions.
Correct Answer: A. It is a selectively permeable barrier that allows water to move
via osmosis but prevents the passage of large solutes.
Rationale: Plasmolysis occurs when water leaves the cell by osmosis in a hypertonic
environment, but the large solutes creating the osmotic gradient cannot cross the
membrane. This demonstrates selective permeability. Option B is incorrect because
water can cross. Option C is incorrect because not all solutes pass freely. Option D is
incorrect because the membrane is not rigid, as evidenced by volume changes.
3. A researcher is investigating the transport of glucose into a cell. They
observe that glucose uptake increases with the concentration gradient, but is
inhibited by a molecule that resembles glucose. This transport mechanism is
most likely:
A. Simple diffusion through the lipid bilayer.
B. Facilitated diffusion via a carrier protein.
,C. Primary active transport using ATP.
D. Secondary active transport coupled with sodium ions.
Correct Answer: B. Facilitated diffusion via a carrier protein.
Rationale: The characteristics described—increased uptake with gradient but
inhibition by a structural analog—are classic hallmarks of carrier-mediated
facilitated diffusion. The inhibition indicates competition for a binding site on the
transporter. Simple diffusion (A) is not inhibited by structural analogs. Active
transport (C and D) requires energy and often moves substances against their
gradient, which is not described in this scenario.
4. Which statement accurately describes the function of the Golgi apparatus in
the endomembrane system?
A. It serves as the primary site for protein synthesis and the initial folding of
polypeptide chains.
B. It modifies, sorts, and packages proteins and lipids received from the
endoplasmic reticulum for delivery to their final destinations.
C. It is responsible for the intracellular digestion of macromolecules and the
recycling of cellular components.
D. It generates ATP through oxidative phosphorylation and is the main energy
source for the cell.
Correct Answer: B. It modifies, sorts, and packages proteins and lipids received
from the endoplasmic reticulum for delivery to their final destinations.
Rationale: The Golgi apparatus is the central sorting and packaging station of the
endomembrane system. Protein synthesis is the primary function of ribosomes (A).
, Intracellular digestion is the function of lysosomes (C). ATP generation is the
primary function of mitochondria (D).
5. Chloroplasts and mitochondria are considered semi-autonomous organelles.
Which of the following pieces of evidence best supports this theory?
A. They are both surrounded by a single lipid bilayer membrane.
B. They both contain their own DNA and ribosomes, and replicate independently
of the nucleus.
C. They are both found exclusively in eukaryotic cells.
D. They are both involved in energy conversion reactions.
Correct Answer: B. They both contain their own DNA and ribosomes, and
replicate independently of the nucleus.
Rationale: The presence of their own DNA and ribosomes, along with the ability to
divide by binary fission, is the primary evidence supporting the endosymbiont
theory and their semi-autonomous nature. They are surrounded by a double
membrane, not a single one (A). Being in eukaryotes (C) and being involved in
energy conversion (D) does not explain their semi-autonomous origin or replication.
6. In a plant cell, which structure is directly responsible for maintaining turgor
pressure against the cell wall?
A. Mitochondria
B. Chloroplast
C. Central vacuole
D. Nucleus
Correct Answer: C. Central vacuole
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS | PLUS RATIONALES |
GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP | STUDY GUIDE |
PRACTICE TEST
1. Which of the following best describes the relationship between the structure
and function of the phospholipid bilayer in a cellular membrane?
A. The hydrophilic phosphate heads face the interior of the membrane, while the
hydrophobic fatty acid tails face the aqueous environment.
B. The hydrophobic fatty acid tails form a barrier to hydrophilic molecules, while
the hydrophilic heads interact with the aqueous intracellular and extracellular
environments.
C. The phospholipids are arranged in a single layer with hydrophobic tails
interacting with the cytoskeleton to provide structural support.
D. The bilayer is static, with phospholipids remaining fixed in place to maintain
membrane rigidity and stability.
Correct Answer: B. The hydrophobic fatty acid tails form a barrier to hydrophilic
molecules, while the hydrophilic heads interact with the aqueous intracellular and
extracellular environments.
Rationale: This is the fundamental description of the phospholipid bilayer's
structure, where the hydrophobic tails face inward creating a barrier to polar
molecules and ions. The hydrophilic phosphate heads face outward, interacting with
water on both sides. Option A incorrectly describes the orientation of the heads and
tails. Option C is incorrect as the membrane is a bilayer, not a monolayer. Option D
is incorrect because the membrane is fluid, not static.
,2. During a laboratory experiment, a student observes that cells placed in a
hypertonic solution undergo plasmolysis. This observation directly supports
which conclusion about the cell membrane?
A. It is a selectively permeable barrier that allows water to move via osmosis but
prevents the passage of large solutes.
B. It is an impermeable barrier that prevents all solutes from entering or leaving
the cell.
C. It is a completely permeable membrane that allows free movement of water
and solutes.
D. It is a rigid structure that maintains cell shape regardless of external osmotic
conditions.
Correct Answer: A. It is a selectively permeable barrier that allows water to move
via osmosis but prevents the passage of large solutes.
Rationale: Plasmolysis occurs when water leaves the cell by osmosis in a hypertonic
environment, but the large solutes creating the osmotic gradient cannot cross the
membrane. This demonstrates selective permeability. Option B is incorrect because
water can cross. Option C is incorrect because not all solutes pass freely. Option D is
incorrect because the membrane is not rigid, as evidenced by volume changes.
3. A researcher is investigating the transport of glucose into a cell. They
observe that glucose uptake increases with the concentration gradient, but is
inhibited by a molecule that resembles glucose. This transport mechanism is
most likely:
A. Simple diffusion through the lipid bilayer.
B. Facilitated diffusion via a carrier protein.
,C. Primary active transport using ATP.
D. Secondary active transport coupled with sodium ions.
Correct Answer: B. Facilitated diffusion via a carrier protein.
Rationale: The characteristics described—increased uptake with gradient but
inhibition by a structural analog—are classic hallmarks of carrier-mediated
facilitated diffusion. The inhibition indicates competition for a binding site on the
transporter. Simple diffusion (A) is not inhibited by structural analogs. Active
transport (C and D) requires energy and often moves substances against their
gradient, which is not described in this scenario.
4. Which statement accurately describes the function of the Golgi apparatus in
the endomembrane system?
A. It serves as the primary site for protein synthesis and the initial folding of
polypeptide chains.
B. It modifies, sorts, and packages proteins and lipids received from the
endoplasmic reticulum for delivery to their final destinations.
C. It is responsible for the intracellular digestion of macromolecules and the
recycling of cellular components.
D. It generates ATP through oxidative phosphorylation and is the main energy
source for the cell.
Correct Answer: B. It modifies, sorts, and packages proteins and lipids received
from the endoplasmic reticulum for delivery to their final destinations.
Rationale: The Golgi apparatus is the central sorting and packaging station of the
endomembrane system. Protein synthesis is the primary function of ribosomes (A).
, Intracellular digestion is the function of lysosomes (C). ATP generation is the
primary function of mitochondria (D).
5. Chloroplasts and mitochondria are considered semi-autonomous organelles.
Which of the following pieces of evidence best supports this theory?
A. They are both surrounded by a single lipid bilayer membrane.
B. They both contain their own DNA and ribosomes, and replicate independently
of the nucleus.
C. They are both found exclusively in eukaryotic cells.
D. They are both involved in energy conversion reactions.
Correct Answer: B. They both contain their own DNA and ribosomes, and
replicate independently of the nucleus.
Rationale: The presence of their own DNA and ribosomes, along with the ability to
divide by binary fission, is the primary evidence supporting the endosymbiont
theory and their semi-autonomous nature. They are surrounded by a double
membrane, not a single one (A). Being in eukaryotes (C) and being involved in
energy conversion (D) does not explain their semi-autonomous origin or replication.
6. In a plant cell, which structure is directly responsible for maintaining turgor
pressure against the cell wall?
A. Mitochondria
B. Chloroplast
C. Central vacuole
D. Nucleus
Correct Answer: C. Central vacuole
