In guard cells when sugar is converted into starch, the stomatal pore
1. Opens partially
2. Closes completely
3. Opens completely
4. Remains unchanged
Diffusion is very imporatnt to plants since:
1. The cells have a permeable cell wall
2. It is the only means for gaseous movement within the plant body.
3. Plants cannot transport material by active transport.
4. They are unable to move towards the xylem
Which of the following is not a characteristic of facilitated transport in plants?
1. Requirement of special membrane proteins
2. Being non-selective
3. Transport saturates
If a pressure greater than atmospheric pressure is applied to a solution, its water potential:
1. Increases
2. Decreases
3. Remains same
4. Becomes zero
Water movement in plants is:
1. Down a potential gradient in apoplast and up the potential gradient in symplast
2. Down a potential gradient in symplast and up the potential gradient in apoplast
3. Up the potential gradient in both apoplast and symplast
4. Down the potential gradient in both apoplast and symplast
What per cent of water reaching them is used by leaves in photosynthesis?
1. Less than 1%
2. About 5 %
3. About 5 % in warm conditions and about 10 % in cold conditions
4. About 50 %
Attraction of water molecules to polar surfaces [such as the surface of tracheary elements] is called as:
1. Connation
2. Adnation
3. Cohesion
4. Adhesion
What are the control points where a plant adjusts the quantity and types of solutes that reach the xylem?
1. Suberin deposited casparian strips
2. Transport proteins of endodermal cell
3. Sclerenchyma around the pericycle
4. The root hairs themselves
Consider the following two statements:
I. The direction of movement in the phloem is bi-directional.
II. The source-sink relationship in plants is variable.
1. Both I and II are correct and II explains I
2. Both I and II are correct but II does not explain I
3. I is correct but II is incorrect
4. Both I and II are incorrect
During translocation of sugars in plants from source to sink:
1. The loading of sugar at source is by active transport and unloading at the sink by passive transport.
2. The loading of sugar at source is by passive transport and unloading at the sink by active transport.
3. Both loading at the source and unloading at the sink are by active transport.
4. Both loading at the source and unloading at the sink are by passive transport.
It is a common observation that CAM plants are not tall. The reason most likely is:
1. They would be unable to move water and minerals to the top of the plant during the day.
2. They would be unable to supply sufficient sucrose for active transport of minerals into the roots during the day or night
3. Transpiration occurs only at night, and this would cause a highly negative ψ in the roots of a tall plant during the day.
4. Since the stomata are closed in the leaves, the Casparian strip is closed in the endodermis strip is closed in the endodermis of the root.
Water logging or over-watering a plant is dangerous and may kill the plant. Why is this so?
1. Water does not have all the necessary minerals a plant needs to grow.
2. Water neutralizes the pH of the soil.
3. The roots are deprived of oxygen.
4. Water lowers the water potential of the roots.
During plasmolysis:
1. Water is lost from the cytoplasm but not from the vacuole
2. Water is first lost from the cytoplasm and then from the vacuole
3. Water is first lost from the vacuole and then from the cytoplasm
4. Water is lost from the vacuole but not from the cytoplasm
What is the first step in the germination of a seed?
(1) pollination
(2) fertilization
(3) imbibition
(4) hydrolysis of starch and other food reserves
Which of the following is/are essential for imbibitions to take place?
I. Water potential gradient between the absorbent and the liquid imbibed
II. Affinity between the adsorbent and the liquid
1. Only II
2. Only I
3. Both I and II
4. None
Consider the following:
I. A decrease in pressure on cell exerted by the wall
II. An increase in water potential of the surroundings
III. The uptake of solutes by the cell
IV. An increase in the tension on the surrounding solution
Which of these would contribute to the uptake of water by the cell?
1. I, II, III
2. II, III, IV
3. I, II, IV
4. I, III, IV
What is true for both symplast and apoplast movement of water in plants?
1. An equal rate of transport
2. Being down a potential gradient
3. Assistance by cytoplasmic streaming
4.Conduction through interconnected protoplasts
Phenyl mercuric acetate (PMA) results in
1. reduced photosynthesis
2. reduced transpiration
3. reduced respiration
4. killing of plants.
Pressure on a plant cell wall caused osmotic movement of water is called:
1. Osmotic pressure
2. Osmotic potential
3. Turgor pressure
4. Hypertonic pressure
The pericycle, which gives rise to lateral roots, consists of:
1. Epithelial cells
2. Meristematic cells
3. Parenchymal cells
4. Endodermal cells
The most abundant solute in the phloem sap is :
1. Potassium ions
2. Sucrose
3. Glucose
4. Starch
The water potential of pure water is
(a) zero
(b) less than zero
(c) more than zero, but less than one
(d) more than one
A few drops of sap were collecled 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?
(a) Acidic
(b) Alkaline
(c) Low refractive index
(d) 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
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
Passage cells are thin-walled cells found in:
1. endodermis of roots facilitating rapid transport of water from cortex to pericycle
2. phloem elements that serve as entry points for substances for transport to other plant
parts
3. testa of seeds to enable emergence of growing embryonic axis during seed
germination
4. central region of style through which the pollen tube grows towards the ovary
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