Biology
Plant Transport and Physiology
1,834 Questions
Access a comprehensive set of questions on plant transport mechanisms and physiological adaptations. Topics include water movement, translocation of food, and plant responses to external stimuli. These biology questions are essential for medical entrance exams and other science competitive tests.
Xylem and phloem transportTranspiration and evaporationPlant adaptationsGeotropic and phototropic responsesWater absorption by rootsRespiration in roots
Plant Transport and Physiology Questions
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Lenticles
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Cuticle
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Stomata
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Rhizoids
C
Correct answer
Explanation
Stomata are microscopic pores found mainly on leaf surfaces that regulate gas exchange and water vapor loss. They open for photosynthesis and close to conserve water, making them the primary site of transpiration in plants.
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Respiration
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Guttation
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Exosmosis
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Transpiration
D
Correct answer
Explanation
Transpiration is the loss of water vapor through stomata in leaves. This process creates transpiration pull that draws water upward through the xylem from roots to leaves, aiding mineral transport and cooling the plant.
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Stem
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Root
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Leaves
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Root hairs
C
Correct answer
Explanation
Leaves have the lowest water potential due to transpiration creating negative pressure (tension). This strong water potential gradient pulls water upward from roots through the xylem vessels, facilitating upward water movement.
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temporary wilting
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incipient wilting
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permanent wilting
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midday desiccation
A
Correct answer
Explanation
The drooping of leaves due to loss of turgor pressure at noon and recovery in the evening is called temporary wilting.
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To reduce transpiration
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To prevent guttation
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To enhance gaseous exchange
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To prevent gaseous exchange
A
Correct answer
Explanation
Leaf hairs (trichomes) create a boundary layer of humid, still air near the leaf surface that reduces water loss through transpiration. They do not significantly affect gaseous exchange or guttation processes.
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Osmotic flow of water into the xylem
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Loss of water from the xylem
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Low water potential of leaves
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High water potential of leaves
A
Correct answer
Explanation
Root pressure is caused by osmotic flow of water into the xylem. Active transport of minerals into the root xylem lowers water potential there, causing water to move osmotically from the soil into the xylem, creating positive hydrostatic pressure.
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Translocation of minerals
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Excretion of sap
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Ascent of sap
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Cooling
B
Correct answer
Explanation
Transpiration has multiple functions: translocation of minerals (moving nutrients upward), ascent of sap (creating upward pull), and cooling (evaporative cooling). Excretion of sap is NOT a function of transpiration - that is gutation.
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Transpiration
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Root pressure
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Osmotic pressure
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Exudation
B
Correct answer
Explanation
Root pressure is related to active water absorption because it requires active transport of minerals into the xylem to create osmotic gradient. This is distinct from passive transpiration pull which relies on physical evaporation.
D
Correct answer
Explanation
K+ ions play a major role in controlling the opening and closing of stomata.
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Mangroves
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Hydrilla
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Water lily
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Water hyacinth
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Lotus
B
Correct answer
Explanation
Tape grass, pond weed and hydrilla are underwater plants which can take carbon dioxide from the water around them and give out oxygen. Their leaves have no pores or stomata. So, the oxygen dissolved in the air is taken in through their body surface.
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Root pressure
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Osmotic pressure
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Wall pressure
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Turgor pressure
A
Correct answer
Explanation
Root pressure is responsible for guttation.
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Movement of solutes into the guard cells
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Movement of solutes outside the guard cells
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Movement of water into the guard cells
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Movement of water outside the guard cells
C
Correct answer
Explanation
On absorbing water, guard cells become turgor and more arched outwards. It widens the aperture between them, and thus opens the stoma.
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Cracking of concrete floor by roots of the adjoining trees
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Development of root pressure
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Rigidity of leaves
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Closure of stomata
D
Correct answer
Explanation
Closure of stomata occurs due to flaccidity of guard cells.
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Deplasmolysis occurs due to loss of water content of a cell.
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Food material is transported through phloem.
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Root pressure forces water up through the stem to leaves.
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Upward flow of minerals occurs through xylem.
A
Correct answer
Explanation
Loss of water content leads to plasmolysis.
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turgor pressure
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wall pressure
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osmotic pressure
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diffusion pressure
A
Correct answer
Explanation
The pressure exerted by the cell contents on the cell wall is called turgor pressure.