The water potential of pure water is

(1) zero

(2) less than zero

(3) more than zero, but less than one

(4) more than one

A few drops of sap were collected by cutting across a plant stem by a suitable method. The sap was tested chemically. Which one of the following test results indicates that it is phloem sap?

(1) Acidic

(2) Alkaline

(3) Low refractive index

(4) The absence of sugar

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