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AS level biology
Unit 1 Mrs Carne
Active transport
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What is active transport?
Active transport is the process by which molecules move from low to high concentration against a
concentration gradient
.
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Why is active transport considered an active process?
Because it requires energy in the form of
ATP
to move molecules against a
concentration gradient
.
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What type of proteins are used in active transport?
Active transport uses
carrier proteins
and
protein channels
.
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What are the steps involved in the process of active transport?
Molecule or ion combines with a specific
carrier protein
on the membrane's outside.
ATP
transfers a
phosphate group
to the carrier protein inside the membrane.
Carrier protein changes shape and transports the molecule or ion across the membrane.
Molecule or ion is released into the
cytoplasm
.
Phosphate ion is released back to the cytoplasm and recombines with
ADP
to form ATP.
Carrier protein returns to its original shape.
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What happens to the phosphate ion after it is released from the carrier protein?
The phosphate ion recombines with ADP to form ATP.
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How do respiratory inhibitors like cyanide affect active transport?
They stop the rate of active transport by preventing
ATP
production.
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Why does the absence of oxygen affect active transport?
Without oxygen,
respiration
does not occur, leading to no ATP production for active transport.
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What is active transport?
The movement of
substances
against a
gradient
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What does 'uptake' refer to in the context of concentration gradients?
A
concentration
gradient
moving from
lower
to
higher
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What does 'down' mean in terms of concentration gradients?
A concentration gradient moving from
higher
to
lower
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What is another term often used for active transport?
Active uptake
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Why is ATP important in active transport?
It provides
energy
for the
transport process
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What is the primary function of carrier proteins in active transport?
To move
molecules
across the membrane
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What are the features of active transport?
Moves
ions/molecules
from lower to higher concentration
Requires energy from
ATP
Affected by respiration
Occurs through
intrinsic carrier proteins
Rate limited by
carrier protein availability
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What processes involve active transport?
Muscle contraction
Nerve impulse transmission
Reabsorption of
glucose
in
kidneys
Mineral uptake in plant root hairs
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How does a carrier protein function in active transport?
It
changes shape
to move a molecule across
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What are the steps of active uptake of a molecule or ion?
Molecule combines with
carrier protein
outside
ATP
transfers a
phosphate group
to the protein
Molecule is released into the
cytoplasm
Phosphate ion returns to cytoplasm, forming ATP
Carrier protein returns to original shape
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What happens to the rate of uptake at higher concentration differences?
It increases and reaches a
plateau
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What effect does an inhibitor have on active transport?
It reduces the rate of
uptake
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Why does cyanide reduce active transport?
It prevents
ATP
production in
mitochondria
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How does increased oxygen availability affect active transport?
It increases active transport by producing more
ATP
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What is the relationship between respiration and active transport?
Active transport requires energy from
respiration
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What are the two types of transport across membranes discussed in the session?
Active transport
and
co-transport
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How do molecules move in simple diffusion?
Down their
concentration gradient
without a
protein
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What is facilitated diffusion?
Movement down
concentration gradient
through a protein
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What characterizes active transport?
Movement against
concentration gradient
using energy
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What is the energy source required for active transport?
ATP
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What happens to ATP during active transport?
It is hydrolyzed into
ADP
and
phosphate
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How does the shape of sodium ions relate to carrier proteins?
Sodium ions fit into
complementary
receptor sites
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What happens to the carrier protein after sodium ions are released?
It returns to its
original shape
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What is co-transport in the context of glucose absorption?
Transport of glucose with
sodium ions
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Why is active transport necessary for glucose absorption in the ileum?
High glucose concentration prevents
facilitated diffusion
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What role do microvilli play in glucose absorption?
They increase
surface area
for absorption
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How does the concentration gradient of sodium ions affect glucose transport?
Lower
sodium
concentration
allows
glucose
to
enter
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What happens to glucose after it enters the epithelial cell?
It moves into the blood by
facilitated diffusion
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Why does blood not accumulate glucose during absorption?
Blood flow carries
glucose
away
quickly
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What is the relationship between active transport and co-transport?
Co-transport is a type of
active transport
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What are the steps involved in active transport of sodium ions?
Sodium ions attach to
carrier protein
.
ATP
hydrolyzes to
ADP
, releasing
phosphate
.
Carrier protein changes shape, releasing sodium ions.
Carrier protein returns to original shape.
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How does co-transport of glucose and sodium ions occur in the ileum?
Sodium ions actively transported into blood.
Lower sodium concentration allows
facilitated diffusion
.
Sodium and glucose bind to
co-transporter
protein.
Both are transported into
epithelial
cell.
Glucose moves into blood by facilitated diffusion.
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What are the key features of active transport and co-transport?
Active transport moves substances against
concentration gradient
.
Requires energy in the form of
ATP
.
Co-transport involves two molecules moving together.
Both processes utilize carrier proteins.
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