Transcript Why does a drop of food coloring diffuse more rapidly in

Why does a drop of food coloring diffuse
more rapidly in warm water than in cold?
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warm water expands and provides
empty space for the food coloring
collisions with rapidly moving water
molecules disperse the food coloring
more quickly
warm food coloring expands,
becomes less dense, and floats
toward the surface
temperature differences increase the
steepness of the concentration
gradient
all of the choices correctly describe
an aspect of diffusion
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Within the phospholipid bilayer, the
hydrophobic tails of each phospholipid are
________.
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oriented lengthwise to form a
ring around the cell
oriented toward each other in
opposing sheets
pointed outward
oriented into the nonpolar
cytosol
curled around the
phospholipid head
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What best explains the contribution of
ATP in the active transport of calcium?
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ATP provides the energy needed to
pump calcium with the concentration
gradient
ATP donates a phosphate group,
which temporarily binds to the
protein pump
to maintain osmotic equilibrium, ATP
enters the cell whenever calcium
leaves
ATP blocks the pump, keeping it
inactive until calcium rises above
normal levels
since ions can't cross membranes,
ATP and calcium ions react to form
calcium phosphate
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Observations of diffusion
confirm that ________.
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larger molecules diffuse more
rapidly than smaller ones
diffusion can occur in liquids, but
not in gels
the rate of diffusion increases as
the concentration gradient
increases
when placed in a hypertonic
medium, a red blood cell will
swell
the energy to move molecules
by diffusion comes from the
hydrolysis of ATP
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Glucose crosses the cell membrane, while
galactose, a very similar molecule, cannot.
How can this be explained?
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glucose crosses by osmosis, but no
concentration gradient exists for
galactose
the membrane transporter is specific
for glucose - galactose has a
different shape and can't enter the
transporter
glucose is larger than galactose, so
the receptor proteins bind glucose
more effectively
glucose is altered chemically by
enzymes so that it can cross the
membrane
glucose gets through but galactose
is blocked by osmosis
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Which observation(s) would distinguish an
active transport system from a passive
system?
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transport rate was sensitive to
temperature
transport rate was sensitive to
pH
transport rate showed little
sensitivity to concentration
gradient
transport rate declined when an
inhibitor was used to prevent the
hydrolysis of ATP
all of the choices would
characterize active transport
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Which of the following do enzymes and
membrane carriers have in common?
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they recognize molecules by
shape
they are made during the
process of protein synthesis
they are constructed from
amino acids
they help determine the
function of the cell
all of the choices are true
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Seawater contains about 4 times as much
solute as blood plasma; blood cells placed in
seawater would:
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swell as water enters
the cell by osmosis
shrink as water leaves
the cell by osmosis
gain salt as it diffuses
across the membrane
lose salt as it diffuses
across the membrane
remain unchanged
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Which of the following would diffuse
most easily across a cell membrane?
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carbon dioxide
glucose
sodium ions
proteins
glycogen
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All of the following increase the rate of
diffusion across a cell membrane except
________.
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1. a steeper
concentration
gradient
2. a lower temperature
3. a smaller size
4. an electric gradient
5. a high osmotic
pressure
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Which process would most quickly provide a
cell with relatively large amounts of a
specific vitamin?
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active transport
phagocytosis
exocytosis
absorption
receptor-mediated
endocytosis
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The pancreatic cells producing digestive enzymes contain
many Golgi bodies. It would be reasonable to assume that
the membrane experiences frequent:
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1. active transport
2. phagocytosis
3. bulk-phase
endocytosis
4. exocytosis
5. receptor-mediated
endocytosis
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Meals with a high salt content can
temporarily cause blood plasma to become
________, and red blood cells to ________.
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hypotonic, shrink
hypertonic, swell
hypotonic, swell
hypertonic, shrink
hypotonic, lyse
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If a 2% sucrose solution were separated from a 7%
sucrose solution by a membrane permeable to water but
not sucrose, which of the following best describes the
movement of water?
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there is no net
movement
there is no movement
the net movement is
from the 2% side to the
7% side
the net movement is
from the 7% side to the
2% side
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What best explains the relationship between
cystic fibrosis (CF) and the CFTR
membrane protein?
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CFTR is an enzyme; non-degraded
substrate accumulates in the cells
causing CF
CFTR is a receptor; cells failing to
receive a growth signal die, causing
CF
CFTR is an adhesion protein; CF
develops when lung cells detach and
clog the airways
CFTR is a channel protein;
insufficient transport of chloride
results in thickened mucus and
causes CF
CFTR is a recognition protein;
immune-cell attack in the lungs of
misidentified cells causes CF
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If a 2% sucrose solution were separated from a 7%
sucrose solution by a membrane permeable to water but
not sucrose, which of the following terms describes the 7%
solution relative to the 2% solution?
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diatonic
isotonic
hypotonic
osmotonic
hypertonic
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Polar molecules, such as the
amino acids, ________.
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are unable to cross cell membranes
and must be synthesized within the
cell
are enzymatically converted to
nonpolar forms before crossing the
membrane
cross membranes by interacting with
membrane transport proteins
pass between the hydrophobic
heads and dissolve through the
hydrophilic tails of the phospholipid
bilayer
examples of all of the choices can
be found with various molecules
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The ________ of the plasma membrane are
arranged as a ________.
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phospholipids, bilayer
phospholipids,
monolayer
triglycerides, bilayer
triglycerides, monolayer
phospholipids, mosaic
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Which of the following can move substances
against a concentration gradient?
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1. active transport
2. facilitated
diffusion
3. passive transport
4. hydrostatic
pressure
5. osmotic pressure
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Cholesterol circulates in the blood
complexed with protein because ________.
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without the added protein
component it would be unable to
cross the membrane of digestive
tract cells
it is a nonpolar molecule and can't
dissolve in the blood plasma
the molecular weight of cholesterol
is too low unless other molecules
are attached to it
cells needing cholesterol can display
the membrane receptor for the
protein component
all of the choices explain aspects of
cholesterol transport
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