Find the correct one.

  • All the solutes have lower water potential than pure water given that solution is under external pressure

  • All the solutions have lower water potential than the pure water

  • All the solutions have higher water potential than the pure water

  • All the solutions have lower water potential than pure water unless solution is under such external pressure which is more than the solute potential

Solute potential is

  • More when solute is more

  • Less when solute is less

  • Always negative

  • All of these

Osmosis is a type of 

  • imbibition of solution   

  • diffusion of solvent

  • evaporation of water   

  • diffusion of solute

In guard cells when sugar is converted into starch, the stomatal pore

  • Opens partially

  • Closes completely
  • Opens completely
  • Remains unchanged

Diffusion is very important to plants since:

  • The cells have a permeable cell wall

  • It is the only means for gaseous movement within the plant body.

  • Plants cannot transport material by active transport.

  • They are unable to move towards the source of the nutrients.

If a pressure greater than atmospheric pressure is applied to a solution, its water potential:

  • Increases

  • Decreases

  • Remains same

  • Becomes zero

What per cent of water reaching them is used by leaves in photosynthesis?

  • Less than 1%

  • About 5 %
  • About 5 % in warm conditions and about 10 % in cold conditions
  • About 50 %

Attraction of water molecules to polar surfaces [such as the surface of tracheary elements] is called as:

  • Connation

  • Adnation

  • Cohesion

  • Adhesion

What are the control points where a plant adjusts the quantity and types of solutes that reach the xylem?

  • Cellulose deposited casparian strips

  • Transport proteins of endodermal cell

  • Sclerenchyma around the pericycle

  • 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.

  • Both I and II are correct and II explains I

  •  Both I and II are correct but II does not explain I

  • I is correct but II is incorrect

  •  Both I and II are incorrect 

During translocation of sugars in plants from source to sink:

  • The loading of sugar at source is by active transport and unloading at the sink by passive transport.

  • The loading of sugar at source is by passive transport and unloading at the sink by active transport.

  • Both loading at the source and unloading at the sink are by active transport.

  • 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:

  • They would be unable to move water and minerals to the top of the plant during the day.

  • They would be unable to supply sufficient sucrose for active transport of minerals into the roots during the day or night

  • Transpiration occurs only at night, and this would cause a highly negative ψ in the roots of a tall plant during the day.

  • 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?

  • Water does not have all the necessary minerals a plant needs to grow.

  • Water neutralizes the pH of the soil.
  • The roots are deprived of oxygen.
  • Water lowers the water potential of the roots.

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 adsorbant and the liquid

  • Only II

  • Only I

  •  Both I and II

  •  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?

  • I, II, III

  • II, III, IV

  • I, II, IV

  • I, III, IV

What is true for both symplast and apoplast movement of water in plants?

  • An equal rate of transport

  • Being down a potential gradient

  • Assistance by cytoplasmic streaming 

  • Conduction through interconnected protoplasts

Phenyl mercuric acetate (PMA) results in

  • reduced photosynthesis

  •  reduced transpiration

  •  reduced respiration

  • killing of plants.

Pressure on a plant cell wall caused osmotic movement of water is called:

  • Osmotic pressure

  • Osmotic potential

  • Turgor pressure

  • Hypertonic pressure

The most abundant solute in the phloem sap is :

  • Potassium ions
  • Sucrose
  • Glucose
  • Starch

A plant requires potassium for:

  • Holding its cells together

  • Synthesizing chlorophyll

  • DNA replication

  • Opening and closing its stomata

The water potential of pure water is

  • zero

  • less than zero

  • more than zero, but less than one

  • 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?

  • Acidic

  • Alkaline

  • Low refractive index

  • The absence of sugar

Root pressure develops due to

  • active absorption

  • low osmotic potential in soil

  • passive absorption

  • increase in transpiration

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

because of

  • dissolved sugars in water

  • tensile strength of water

  • lignification of xylem vessels

  • positive root pressure

Transpiration and root pressure cause water to rise in plants by

  • Pulling it upward

  • pulling and pushing it, respectively

  • pushing it upward

  • pushing and pulling it, respectively

In a ring girdled plant ?

  • the shoot dies first

  • the root dies first

  • the shoot and root die together

  • Neither root nor shoot will die

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

  • Transpiration

  • Potassium influx and efflux

  • Starch hydrolysis

  • Guard cell photosynthesis

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

  • Requirement of special membrane proteins

  • High selectivity

  • Transport saturation

  • Uphill transport

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

  • Calcium

  • Potassium

  • Sulphur

  • Phosphorus

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

  • lignified thick walls

  • cohesion and adhesion

  • weak gravitational pull

  • transpiration pull

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