4/27/25, 11:21
AM
(2) BIO 224 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED GRADED A++
Save
Terms in this set (362)
Intracellular aqueous environment affects
Fundamental Problem organic molecule function
• Protein function (e.g. enzymes) is affected by
ion concentration.
• Protein function is optimal within a narrow
range of inorganic ion concentration
- Maintaining water and salt balance in the
animal body
Osmoregulation - The selective retention and
excretion of water and salt from
the body Animals can live in
diverse environments
• Terrestrial: can dehydrate so need to retain
water
• Aquatic: need to maintain salt balance
Osmosis Water molecules move across a
selectively permeable membrane from
a region of high concentration to a
region of low concentration.
Osmolality Osmotic concentration (osmotic pressure) of a
solution
- Number of osmoles per kg of solute
- The solution with high
osmolality on one side
Hyper, Hypo, Iso of a membrane is
Osmotic
hyperosmotic, and the
solution with low
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,4/27/25, 11:21
AM
osmolality is
hyposmotic.
- Isosmotic: Solutions on both sides of the
membrane have the same osmotic
concentration.
• Regulate water/solutes in blood, secondarily
in interstitial fluid.
• Cells also have some
ability to alter their cell
Osmoregulatory
Systems volume. REMEMBER!
• Solute: a substance added to a
solvent to form a solution (e.g. salt
and other ions)
• Solvent: substance that dissolves
the solute particles during formation
of a solution (e.g. water)
-Cells have limited ability to change their
volume by moving ions and water.
Why is ECF - The cell membrane is
(Extracellular Fluid) semipermeable, so changes in ECF
used for affect the cell more easily.
- ICF must remain stable because:
osmoregulation
-- Intracellular ion levels are crucial for proper
instead of ICF enzyme and protein function.
(Intracellular Fluid)? - ECF is more stable and easier
to regulate, making it a better
buffer for maintaining balance.
- Interstitial fluid and blood plasma have
similar ion composition.
- Inside cells (ICF) can be very different
Ion Composition of from outside.
the Cell -Cells use ATP to
control ion levels
inside. But when it
comes to water:
-Most animal cells are water-permeable.
- They can maintain ion differences, but not
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, 4/27/25, 11:21
AM
osmotic (water) differences.
Distinguished by their effects on
macromolecules
- Perturbing
• Disrupt macromolecular function
• Na+, K+, Cl–, SO4+, charged amino acids
Classification of - Compatible
Solutes • Little effect on macromolecular function
• Polyols (glycerol, glucose) and uncharged
amino acids
- Counteracting
• Disrupt macromolecular functions on their
own
• Counteract disruptive effects of other
solutes when employed in combination
Epithelial cells use two main routes of
transport
- Transcellular transport
• Movement through the cell across
membranes
- Paracellular transport
Cellular Transport of • Movement between cells
Ions and Water
• “Leaky” vs. “tight” epithelia
- Types of transporters
• Na+K+ATPase, Ca2+-ATPase
• Ion channels (Cl–, K+, Na+, Ca2+)
• Electroneutral cotransporters
• Electroneutral exchangers
- Water moves from
low solute
Movement of Water concentration (high
water potential) to
high solute
concentration (low
water potential) →
osmotic gradient
- Water can not be actively pumped
3/
18
AM
(2) BIO 224 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED GRADED A++
Save
Terms in this set (362)
Intracellular aqueous environment affects
Fundamental Problem organic molecule function
• Protein function (e.g. enzymes) is affected by
ion concentration.
• Protein function is optimal within a narrow
range of inorganic ion concentration
- Maintaining water and salt balance in the
animal body
Osmoregulation - The selective retention and
excretion of water and salt from
the body Animals can live in
diverse environments
• Terrestrial: can dehydrate so need to retain
water
• Aquatic: need to maintain salt balance
Osmosis Water molecules move across a
selectively permeable membrane from
a region of high concentration to a
region of low concentration.
Osmolality Osmotic concentration (osmotic pressure) of a
solution
- Number of osmoles per kg of solute
- The solution with high
osmolality on one side
Hyper, Hypo, Iso of a membrane is
Osmotic
hyperosmotic, and the
solution with low
1/
18
,4/27/25, 11:21
AM
osmolality is
hyposmotic.
- Isosmotic: Solutions on both sides of the
membrane have the same osmotic
concentration.
• Regulate water/solutes in blood, secondarily
in interstitial fluid.
• Cells also have some
ability to alter their cell
Osmoregulatory
Systems volume. REMEMBER!
• Solute: a substance added to a
solvent to form a solution (e.g. salt
and other ions)
• Solvent: substance that dissolves
the solute particles during formation
of a solution (e.g. water)
-Cells have limited ability to change their
volume by moving ions and water.
Why is ECF - The cell membrane is
(Extracellular Fluid) semipermeable, so changes in ECF
used for affect the cell more easily.
- ICF must remain stable because:
osmoregulation
-- Intracellular ion levels are crucial for proper
instead of ICF enzyme and protein function.
(Intracellular Fluid)? - ECF is more stable and easier
to regulate, making it a better
buffer for maintaining balance.
- Interstitial fluid and blood plasma have
similar ion composition.
- Inside cells (ICF) can be very different
Ion Composition of from outside.
the Cell -Cells use ATP to
control ion levels
inside. But when it
comes to water:
-Most animal cells are water-permeable.
- They can maintain ion differences, but not
2/
18
, 4/27/25, 11:21
AM
osmotic (water) differences.
Distinguished by their effects on
macromolecules
- Perturbing
• Disrupt macromolecular function
• Na+, K+, Cl–, SO4+, charged amino acids
Classification of - Compatible
Solutes • Little effect on macromolecular function
• Polyols (glycerol, glucose) and uncharged
amino acids
- Counteracting
• Disrupt macromolecular functions on their
own
• Counteract disruptive effects of other
solutes when employed in combination
Epithelial cells use two main routes of
transport
- Transcellular transport
• Movement through the cell across
membranes
- Paracellular transport
Cellular Transport of • Movement between cells
Ions and Water
• “Leaky” vs. “tight” epithelia
- Types of transporters
• Na+K+ATPase, Ca2+-ATPase
• Ion channels (Cl–, K+, Na+, Ca2+)
• Electroneutral cotransporters
• Electroneutral exchangers
- Water moves from
low solute
Movement of Water concentration (high
water potential) to
high solute
concentration (low
water potential) →
osmotic gradient
- Water can not be actively pumped
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18
