The most abundant solute in the phloem sap is :
1. Potassium ions
2. Sucrose
3. Glucose
4. Starch
Consider the following statements:
I. The apoplast system is continuous throughout the plant, except at the casparian strips of the endodermis.
II. Transport proteins of endodermal cells are control points, where a plant adjusts the quantity and type of solute that reaches the xylem.
III.A plant loses about twice as much water as a plant for the same amount of fixed.
Which of the above statements are true?
1. I and II only
2. I and III only
3. II and III only
4. I, II and III
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
Which one of the following elements in plants is not remobilised?
1. Calcium
2. Potassium
3. Sulphur
4. Phosphorus
The translocation of organic solutes in sieve tube members is supported by:
1. root pressure and transpiration pull
2. P-proteins
3. mass flow involving a carrier and ATP
4. cytoplasmic streaming
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
Transpiration is very important for plants because it helps in
1. the absorption of water from soil
2. the cooling of leaves at high temperature
3. the movement of water and minerals absorbed by roots to various parts of the plant
4. all of the above
Wooden doors swell up and get stuck during the rainy season. This is due to the
phenomenon of
1. imbibition
2. endosmosis
3. capillarity
4. deplasmolysis.
Stomata opens:
(1) in day time - for gaseous exchange
(2) in day time - no gaseous exchange
(3) in night time only - for gaseous exchange
(4) in night time only - no gaseous exchange