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

1. Cellulose 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 is by passive transport.

2. The loading of sugar at source is by passive transport and unloading at the sink is 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 $\mathrm{\psi }$ 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.

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

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 the above 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