Transport in Plants

Which one gives the most valid and recent explanation for stomatal movement?

1. Starch hydrolysis
2. Guard cell photosynthesis
3. Transpiration
4. Potassium influx and efflux

Which of the following criteria does not pertain to facilitated transport?

1. Transport saturation
2. Uphill transport
3. Requirement of special membrane proteins
4. High selectivity

Function of companion cells is :

1. Providing water to phloem
2. Loading of sucrose into sieve elements
3. Loading of sucrose into sieve elements by passive transport
4. Providing energy to sieve elements for active transport

Guttation is the result of

1. diffusion
2. transpiration
3. osmosis
4. root pressure

Guard cells help in

1. transpiration
2. guttation
3. fighting against infection
4. protection against grazing

The rupture and fractionation do not usually occur in the water column in vessel/tracheids during the ascent of sap because of

1. weak gravitational pull
2. transpiration pull
3. lignified thick walls
4. cohesion and adhesion

Two cells A and B are contiguous. Cell A has osmotic pressure 10 atm, turgor pressure 7 atm and diffusion pressure deficit 3 atm. Cell B has osmotic pressure 8 atm, turgor pressure 3 atm and diffusion pressure deficit 5 atm. The result will be

1. no movement of water
2. equilibrium between the two
3. movement of water from cell A to B
4. movement of water from cell B to A

The translocation of organic solutes in sieve tube members is supported by

1. cytoplasmic streaming
2. root pressure and transpiration pull
3. P-proteins
4. mass flow involving a carrier and ATP.

Potometer works on the principle of

1. osmotic pressure
2. amount of water absorbed equals the amount transpired
3. root pressure
4. potential difference between the tip of the tube and that of the plant.

Stomata of a plant open due to

1. influx of potassium ions
2. efflux of potassium ions
3. influx of hydrogen ions
4. influx of calcium ions