biology : class11 Imbibition versus Osmosis : Definition, Mechanism, Examples, Importance : Imbibition MCQ Questions and Answers
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Imbibition versus Osmosis
MCQ questions and answers.
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MCQ Questions
1. A dry seed swells when placed in pure water, even though no living membrane is required for the initial water uptake. Which process best explains this observation?
A.
Osmosis, because water moves through the seed coat into the seed
B.
Imbibition, because hydrophilic colloids in the seed adsorb water
C.
Active transport, because seed cells expend ATP to absorb water
D.
Diffusion of solutes, because dissolved substances enter the seed first
Correct Answer:
Imbibition, because hydrophilic colloids in the seed adsorb water
Explanation:
The initial swelling of a dry seed is imbibition. Hydrophilic substances such as cellulose, proteins, and starch adsorb water and swell; a selectively permeable membrane and living metabolism are not essential for this initial process.
2. Which combination most accurately distinguishes imbibition from osmosis?
A.
Imbibition requires a selectively permeable membrane, whereas osmosis does not
B.
Imbibition involves adsorption by hydrophilic colloids, whereas osmosis involves solvent movement across a selectively permeable membrane
C.
Imbibition occurs only in living cells, whereas osmosis occurs only in dead tissues
D.
Imbibition transports solutes, whereas osmosis transports only proteins
Correct Answer:
Imbibition involves adsorption by hydrophilic colloids, whereas osmosis involves solvent movement across a selectively permeable membrane
Explanation:
Imbibition is the adsorption and absorption of water by hydrophilic colloidal materials, often accompanied by swelling. Osmosis is the net movement of solvent, usually water, through a selectively permeable membrane because of a difference in water potential.
3. A block of dry gelatin is placed in pure water and swells, while a living cell placed in a hypotonic solution also gains water. What is the most important difference between the two processes?
A.
Gelatin swelling is driven by adsorption by hydrophilic colloids, whereas cell water uptake is osmosis across a selectively permeable membrane
B.
Gelatin swelling is osmosis through a plasma membrane, whereas cell water uptake is imbibition by cellulose
C.
Both processes are identical because both involve water entering a material
D.
Gelatin swelling requires ATP, whereas cell water uptake occurs without any water-potential difference
Correct Answer:
Gelatin swelling is driven by adsorption by hydrophilic colloids, whereas cell water uptake is osmosis across a selectively permeable membrane
Explanation:
Gelatin contains hydrophilic colloidal material that directly adsorbs water, producing imbibition. A living cell takes up water osmotically through its selectively permeable plasma membrane when an appropriate water-potential gradient exists.
4. Which observation would provide the strongest evidence that water uptake is primarily due to imbibition rather than osmosis?
A.
Water uptake stops when the external solution becomes isotonic to the cell sap
B.
Water uptake occurs in a nonliving, dry hydrophilic material lacking a selectively permeable membrane
C.
Water moves into a cell through its plasma membrane from a region of higher water potential
D.
A cell loses water when placed in a hypertonic solution
Correct Answer:
Water uptake occurs in a nonliving, dry hydrophilic material lacking a selectively permeable membrane
Explanation:
Imbibition can occur in nonliving materials such as dry wood, gelatin, or seed components and does not require a selectively permeable membrane. The other observations describe characteristic osmotic behavior of cells.
5. Why can imbibition generate considerable swelling pressure, whereas osmosis in a fully turgid cell may cease despite water being available outside?
A.
Imbibition is caused by solute synthesis, whereas osmosis is caused by ATP hydrolysis
B.
Hydrophilic surfaces lower water potential during imbibition, while turgor pressure can oppose further osmotic water entry
C.
Osmosis always requires dry colloids, whereas imbibition requires a concentrated cell sap
D.
Imbibition involves solute movement through membranes, while osmosis involves only air movement
Correct Answer:
Hydrophilic surfaces lower water potential during imbibition, while turgor pressure can oppose further osmotic water entry
Explanation:
Hydrophilic colloids exert a strong attraction for water and develop imbibitional pressure as they swell. In osmosis, water entry into a cell increases turgor pressure, which can balance the water-potential gradient and stop net movement.
6. A researcher removes the plasma membrane from a dry plant cell wall and places the wall in water. The wall still absorbs water and expands. Which conclusion is most appropriate?
A.
The process must be osmosis because plant cell walls contain cellulose
B.
The process is imbibition because cellulose is hydrophilic and the plasma membrane is absent
C.
The process is active transport because cellulose molecules pump water inward
D.
The process is facilitated diffusion because water uses membrane proteins in the wall
Correct Answer:
The process is imbibition because cellulose is hydrophilic and the plasma membrane is absent
Explanation:
Cellulose in the cell wall has hydrophilic groups that attract and hold water, causing swelling by imbibition. Osmosis cannot be the primary explanation when the selectively permeable plasma membrane is absent.
7. Which statement about the role of a selectively permeable membrane is correct when comparing imbibition and osmosis?
A.
It is essential for both processes because water cannot move without a membrane
B.
It is essential for osmosis but not for the basic process of imbibition
C.
It is essential for imbibition but prevents osmosis
D.
It is irrelevant to osmosis because osmosis occurs only through cell walls
Correct Answer:
It is essential for osmosis but not for the basic process of imbibition
Explanation:
Osmosis is defined by solvent movement across a selectively permeable membrane. Imbibition is the adsorption of water by hydrophilic substances and can occur in materials such as dry wood or gelatin without such a membrane.
8. A dry bean is placed in distilled water. During the first phase, it swells rapidly; after cellular membranes become functional and solutes are redistributed, membrane-dependent water movement becomes important. Which sequence is most accurate?
A.
Osmosis followed by imbibition
B.
Imbibition followed by osmosis
C.
Diffusion followed by active transport
D.
Active transport followed by imbibition
Correct Answer:
Imbibition followed by osmosis
Explanation:
The dry seed initially takes up water through imbibition by hydrophilic colloids in its cell walls and storage materials. Once functional membranes and internal solute gradients are involved, further water movement can occur osmotically.
9. Which situation most clearly demonstrates that a concentration gradient alone does not define imbibition?
A.
Water enters a cell through a selectively permeable membrane because of a water-potential difference
B.
A dry polysaccharide matrix absorbs water even when no dissolved solute gradient is established
C.
A cell loses water to a surrounding concentrated solution
D.
Water crosses a membrane from dilute solution toward concentrated solution
Correct Answer:
A dry polysaccharide matrix absorbs water even when no dissolved solute gradient is established
Explanation:
Imbibition depends primarily on the attraction of water to hydrophilic colloids and does not require a dissolved-solute concentration gradient. Osmosis, in contrast, is membrane-dependent and results from differences in water potential.
10. A student claims that every instance of water entering a plant structure is osmosis. Which example most decisively disproves the claim?
A.
Water entering a root hair from moist soil through the plasma membrane
B.
Water entering a guard cell when its water potential is lower than that of the surrounding solution
C.
Dry wooden tissue swelling after being immersed in water without a living membrane
D.
Water entering a plant cell until its turgor pressure counterbalances the water-potential gradient
Correct Answer:
Dry wooden tissue swelling after being immersed in water without a living membrane
Explanation:
Dry wood swells because hydrophilic cell-wall components imbibe water, even though the tissue is nonliving and lacks functional plasma membranes. The other examples involve membrane-dependent water movement and are therefore osmotic.
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