Root pressure develops due to

1. active absorption

2. low osmotic potential in soil

3. passive absorption

4. increase in transpiration

A column of water within xylem vessels of tall trees does not break under its weight

because of

1. dissolved sugars in water

2. tensile strength of water

3. lignification of xylem vessels

4. positive root pressure

Transpiration and root pressure cause water to rise in plants by

1. Pulling it upward

2. pulling and pushing it, respectively

3. pushing it upward

4. pushing and pulling it, respectively

In a ring girdled plant ?

1. the shoot dies first

2. the root dies first

3. the shoot and root die together

4. Neither root nor shoot will die

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

1. Transpiration

2. Potassium influx and efflux

3. Starch hydrolysis

4. Guard cell photosynthesis

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

1. Requirement of special membrane proteins

2. High selectivity

3. Transport saturation

4. Uphill transport

Which one of the following elements in plants is not remobilised?

1. Calcium

2. Potassium

3. Sulphur

4. Phosphorus

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

1. lignified thick walls

2. cohesion and adhesion

3. weak gravitational pull

4. transpiration pull

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. Movement of water from cell B to A

2. No movernent of water

3. Equilibrium between the two

4. Movement of water from cell A to B

Substances that enter the living cells by facilitated diffusion are:

1. generally polar in nature

2. transported in the direction of the concentration gradient 

3. transported with the help of carrier proteins 

4. all of the above