General Biology I - BSC 1010C - Chapter 7: Membrane
Structure and Function Questions With Complete Solutions
Compare and contrast how a hyper-, hypo-, and isotonic solution
affect an animal and plant cell. Correct Answers Plant cells are
turgid in a hypotonic environment, flaccid in an isotonic
environment, and plasmolyzed in a hypertonic environment.
Animal cells are swollen and may burst in a hypotonic
environment, normal in an isotonic environment, and shriveled
in a hypertonic environment. An animal cell fares best in an
isotonic environment, while plant cells are healthiest in a
hypotonic environment.
Describe the differences and similarities between: diffusion,
passive transport, osmosis, facilitated diffusion, and active
transport. Correct Answers Diffusion is the movement of
solutes from high to low concentration, and osmosis is the
movement of solvent particles from low to high concentration.
Passive transport is diffusion of a substance across a membrane
with no energy investment; substances are allowed to move
where those substances naturally move to. Facilitated diffusion
requires no energy and substances diffuse through a selectively
permeable membrane from high to low concentration. Active
transport employs proteins that use energy to move solutes
against the gradient; substances are moved in directions that
those substances will not naturally move.
Describe the terms: diffusion, osmosis, concentration gradient,
and equilibrium. Correct Answers Diffusion is the spreading of
substance molecules from a region where the substance is more
concentrated to another region where it is less concentrated.
, Osmosis is the diffusion of water across a selectively permeable
membrane. The concentration gradient is a region along which
the concentration of a chemical substance in a solution increases
or decreases. Equilibrium is the state in which all the solute
particles in a substance are spread out evenly.
How are proteins arranged in the cell membrane? Correct
Answers Integral proteins penetrate the hydrophobic core of the
lipid bilayer; span the membrane. Hydrophobic regions consist
of 1+ stretches of amino acids, coiled in α-helices. Peripheral
proteins are not embedded in the lipid bilayer; they are
appendages loosely bound to the surface of the membrane.
How is an integral protein different than a peripheral protein?
Correct Answers Integral proteins penetrate the hydrophobic
core of the lipid bilayer. Many are transmembrane proteins,
which span the membrane; other integral proteins extend only
partway into the hydrophobic core or have a hydrophilic bilayer.
Peripheral proteins are not embedded in the lipid bilayer at all;
they are only attached to the outside of the phospholipid bilayer
(the hydrophilic region) toward the outside environment.
Identify and explain the various mechanisms that permit the
movement of large substances across the cell membrane. Correct
Answers Exocytosis is the cellular secretion of biological
molecules by the fusion of vesicles containing them with the
plasma membrane. Endocytosis is the cellular uptake of
biological molecules and particulate matter via formation of
vesicles from the plasma membrane. Phagocytosis is a type of
endocytosis in which large particulate substances or small
organisms are taken up by a cell; it is also known as cellular
Structure and Function Questions With Complete Solutions
Compare and contrast how a hyper-, hypo-, and isotonic solution
affect an animal and plant cell. Correct Answers Plant cells are
turgid in a hypotonic environment, flaccid in an isotonic
environment, and plasmolyzed in a hypertonic environment.
Animal cells are swollen and may burst in a hypotonic
environment, normal in an isotonic environment, and shriveled
in a hypertonic environment. An animal cell fares best in an
isotonic environment, while plant cells are healthiest in a
hypotonic environment.
Describe the differences and similarities between: diffusion,
passive transport, osmosis, facilitated diffusion, and active
transport. Correct Answers Diffusion is the movement of
solutes from high to low concentration, and osmosis is the
movement of solvent particles from low to high concentration.
Passive transport is diffusion of a substance across a membrane
with no energy investment; substances are allowed to move
where those substances naturally move to. Facilitated diffusion
requires no energy and substances diffuse through a selectively
permeable membrane from high to low concentration. Active
transport employs proteins that use energy to move solutes
against the gradient; substances are moved in directions that
those substances will not naturally move.
Describe the terms: diffusion, osmosis, concentration gradient,
and equilibrium. Correct Answers Diffusion is the spreading of
substance molecules from a region where the substance is more
concentrated to another region where it is less concentrated.
, Osmosis is the diffusion of water across a selectively permeable
membrane. The concentration gradient is a region along which
the concentration of a chemical substance in a solution increases
or decreases. Equilibrium is the state in which all the solute
particles in a substance are spread out evenly.
How are proteins arranged in the cell membrane? Correct
Answers Integral proteins penetrate the hydrophobic core of the
lipid bilayer; span the membrane. Hydrophobic regions consist
of 1+ stretches of amino acids, coiled in α-helices. Peripheral
proteins are not embedded in the lipid bilayer; they are
appendages loosely bound to the surface of the membrane.
How is an integral protein different than a peripheral protein?
Correct Answers Integral proteins penetrate the hydrophobic
core of the lipid bilayer. Many are transmembrane proteins,
which span the membrane; other integral proteins extend only
partway into the hydrophobic core or have a hydrophilic bilayer.
Peripheral proteins are not embedded in the lipid bilayer at all;
they are only attached to the outside of the phospholipid bilayer
(the hydrophilic region) toward the outside environment.
Identify and explain the various mechanisms that permit the
movement of large substances across the cell membrane. Correct
Answers Exocytosis is the cellular secretion of biological
molecules by the fusion of vesicles containing them with the
plasma membrane. Endocytosis is the cellular uptake of
biological molecules and particulate matter via formation of
vesicles from the plasma membrane. Phagocytosis is a type of
endocytosis in which large particulate substances or small
organisms are taken up by a cell; it is also known as cellular
