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 important 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 source of the nutrients.

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

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. 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.