Osmosis in Plant and Animal Cells

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Questions and Answers

Considering the implications of osmotic pressure on cellular integrity, under which conditions would a eukaryotic cell, typically devoid of a rigid cell wall, demonstrate the most pronounced cytolysis, assuming an uncompensated influx of water?

When the cell is in a severely hypotonic solution where the external osmotic pressure approaches zero. (correct)
When the cell is in a hypertonic solution containing a mixture of permeant and impermeant osmolytes allowing a transient state of equilibrium.
When the cell is in an isotonic solution with an initially high concentration of impermeant solutes within the cytoplasm.
When the cell is rapidly transferred from a moderately hypertonic solution to a slightly hypotonic solution.

Given the complexities of plant cell turgor pressure regulation, which scenario would most likely result in plasmolysis despite active cellular mechanisms designed to maintain osmotic balance?

Prolonged exposure to a moderately hypertonic solution coupled with the inhibition of vacuolar proton pumps. (correct)
Maintenance in an isotonic solution with blocked ion channels that are critical for osmoregulation.
Exposure to a slightly hypertonic solution where aquaporin activity is upregulated.
Rapid transition from a hypertonic to a hypotonic environment facilitated by increased synthesis of compatible solutes.

In the context of cellular osmosis, what biophysical phenomenon primarily dictates the rate of water movement across a selectively permeable membrane when facing a steep osmotic gradient, assuming all other factors are held constant?

The absolute difference in solute concentration, irrespective of solute permeability.
The effective osmotic pressure, accounting for both solute concentration and reflection coefficients. (correct)
The membrane surface area, modulated by changes in cell volume.
The rate of active transport of osmolytes counteracting the osmotic gradient.

Considering the role of lipid composition in modulating membrane permeability, how would increasing the proportion of unsaturated fatty acids within the phospholipid bilayer of a cell membrane most directly impact its osmotic response?

<p>Increase membrane fluidity, potentially accelerating water movement and exacerbating osmotic imbalances. (B)</p> Signup and view all the answers

Under conditions of extreme osmotic stress, what adaptive mechanism would be LEAST effective in preventing irreversible cellular damage, considering both plant and animal cell strategies for osmoregulation?

<p>Controlled enzymatic degradation of structural proteins to temporarily reduce intracellular osmotic pressure. (B)</p> Signup and view all the answers

Flashcards

Hypertonic Solution

Describes a solution with a higher solute concentration outside the cell, causing water to move out.

Isotonic Solution

Describes a solution with an equal solute concentration inside and outside the cell, resulting in no net water movement.

Hypotonic Solution

Describes a solution with a lower solute concentration outside the cell, drawing water into the cell.

Crenation

The shrinking of an animal cell when placed in a hypertonic solution due to water loss.

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Lysis

The swelling and potential bursting of an animal cell when placed in a hypotonic solution due to water gain.

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Study Notes

Osmosis in Plant and Animal Cells

The diagrams illustrate how cells change due to osmosis, where water constantly moves across cell membranes through random motion.
Arrow sizes indicate the relative amount of water movement into and out of the cells.
Both plant and animal cells have selectively permeable membranes.
Plant cells additionally have a permeable, rigid, outer cell wall.

Animal Cell

Hypertonic Solution (A): Cell is crenated
Isotonic Solution (B): Cell is normal
Hypotonic Solution (C): Cell is lysed

Plant Cell

Hypertonic Solution (D): Cell is plasmolysed
Isotonic Solution (E): Cell is normal
Hypotonic Solution (F): Cell is turgid

Water Movement

Cells That Have Taken in Water

B, C, E, F

Cells That Have Lost Water

A, D

Cells That Show No Change In Water

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Description

Explore osmosis in plant and animal cells. Diagrams show cell changes due to water movement across membranes. Learn how cells respond in hypertonic, isotonic, and hypotonic solutions, noting differences due to the plant cell wall.