Prepare for NEET Biology Transport in Plants (Long Distance Transport) with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert solutions to examine xylem and phloem transport mechanisms.
NEET Questions / Botany / Transport in Plants / Long Distance Transport
A researcher is studying long-distance transport in a plant. They introduce a radioactive tracer into the phloem sap of a source leaf. Which of the following would LEAST likely be observed after a period of time?
Movement of the tracer towards a developing fruit
Presence of the tracer in the root tips
Detection of the tracer in a sink leaf
Significant accumulation of the tracer in mature xylem vessels of the source leaf
Which of the following manipulations would MOST directly inhibit the loading of sucrose into the sieve tube elements at the source?
Decreasing the hydrostatic pressure in the sieve tube elements
Blocking plasmodesmata between companion cells and sieve tube elements
Increasing the concentration of sucrose in the sink
Inhibition of apoplastic proton pumps in companion cells
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.
Girdling experiments, where the bark of a tree is removed in a ring around the trunk, demonstrate the importance of phloem for translocation. Which observation is NOT expected after girdling?
Accumulation of sugars above the girdle.
Swelling of the bark above the girdle.
Eventual death of the roots due to lack of nutrients.
Increased sugar concentration above the girdle and decreased sugar concentration below the girdle, with no effect on xylem function.
Which combination of factors would MOST effectively enhance the rate of transpiration in a plant?
Low light intensity, high humidity, open stomata, and still air
High light intensity, high humidity, closed stomata, and strong wind
Low light intensity, low humidity, closed stomata, and still air
High light intensity, low humidity, open stomata, and strong wind
A plant is exposed to a chemical that specifically inhibits the activity of aquaporins in root cells. Which of the following would be the MOST direct consequence of this inhibition?
Increased rate of transpiration
Enhanced mineral absorption
Stimulation of phloem loading
Reduced water uptake by the roots
Which of the following is NOT a major driving force for long-distance transport in plants?
Transpiration pull
Root pressure
Active transport
Diffusion
The Casparian strip in the endodermis primarily restricts the movement of water via the:
Apoplast
Symplast
Transmembrane pathway
Vacuolar pathway
Girdling experiments demonstrate the role of which tissue in the transport of sugars?
Phloem
Xylem
Cambium
Pith
The pressure-flow hypothesis explains the movement of:
Sugars in phloem
Water in xylem
Minerals in xylem
Water in phloem
