Prepare for NEET Biology Transport in Plants with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert guidance to understand xylem, phloem, and movement of water.
A researcher is studying facilitated diffusion of a novel solute 'X' across a cell membrane using an artificial lipid bilayer system. They observe that increasing the concentration of X on one side of the membrane increases the rate of transport, but only up to a certain point. Beyond this point, further increases in X concentration do not affect the transport rate. Which of the following BEST explains this observation?
The membrane has reached its maximum permeability for X.
The solute X is being actively transported at higher concentrations.
Saturation of the carrier proteins
The solute X is inhibiting its own transport through feedback regulation.
In a hypothetical cell, the facilitated diffusion of a solute 'Y' is observed to be significantly faster than predicted by simple diffusion models. However, the transport rate plateaus at high concentrations of Y. Which of the following is the MOST likely explanation for this observation?
The cell membrane is selectively permeable to Y.
The solute Y is transported via carrier proteins.
The solute Y is undergoing active transport.
The cell is modifying Y during transport.
Which of the following factors DOES NOT significantly affect the rate of imbibition?
Temperature
Affinity of the imbibant for the liquid
Surface area of the imbibant
External hydrostatic pressure
The pressure-flow hypothesis explains the translocation of sugars in the phloem. Which of the following statements regarding this hypothesis is INCORRECT?
Active loading of sugars at the source creates a high solute concentration in the sieve tubes.
Water moves from the xylem to the phloem at the source, increasing turgor pressure.
Sugars are unloaded at the sink, lowering the solute concentration and water potential.
Water moves from the sink to the source via the phloem, driven by a pressure gradient.
The apoplast pathway in plants is interrupted by the Casparian strip. Which of the following statements about its impact on water movement is most accurate?
It forces water and dissolved minerals to enter the symplast before reaching the stele.
It facilitates the rapid movement of water through the cortex via plasmodesmata.
It prevents the passage of water into the root hair cells.
It increases the rate of transpiration by reducing the resistance to water flow.
Under which of the following specific environmental conditions would guttation be LEAST likely to occur?
Cool, humid night with high soil moisture
Warm, humid morning with adequate soil moisture
Cool, dry night with moderate soil moisture
Hot, dry day with low soil moisture
