Identify the incorrect statement regarding aquaporins:
1. Water channels are transmembrane proteins made up of eight different types of aquaporins.
2. Water moves most rapidly in tissues that have aquaporin water channels.
3. The presence of water channels increases membrane permeability to water.
4. Aquaporins selectively conduct water molecules in and out of the cell but allow some passage of protons.

Study the given figure where five beakers filled with a solution have a bag with solution of certain molarity suspended in each of them. The bags are made up of semi-permeable membranes.

What would be the correct order of the beakers in order of the mass of bags after 30 minutes have been allowed to run the experiment [bag with smallest mass to be placed first]?
1. 1, 2, 3, 4, 5
2. 1, 5, 2, 3, 4
3. 4, 3, 2, 5, 1
4. 2, 1, 5, 3, 4

What is incorrect regarding apoplast transport in plants?
1. The apoplast is formed by the continuum of cell walls of adjacent cells as well as the extracellular spaces.
2. Transport velocity is lower in the apoplast than in the symplast.
3. Apoplast transport also accounts for a higher proportion of water transport in plant tissues than does symplastic transport.
4. The apoplastic pathway is also involved in passive exclusion.

Root pressure is caused by:
1. active distribution of mineral nutrient ions into the root xylem.
2. passive distribution of mineral nutrient ions into the root xylem.
3. a lower water potential in soil than the root cells.
4. transpirational pull.

Mass flow of liquid water from roots to the leaves is primarily driven by:
1. Root pressure
2. Capillary action
3. Water potential differences
4. Active transport

Identify the incorrect statement regarding cohesion-tension theory that explains the process of water flow upwards through the xylem of the plants:

1. Transpiration in leaves creates tension (differential pressure) in the cell walls of mesophyll cells.

2. Because of this tension, water is being pulled up from the roots into the leaves.

3. The pull is helped by cohesion (the stickiness between water molecules and the hydrophilic cell walls of plants) and adhesion (the pull between individual water molecules, due to hydrogen bonds).

4. This mechanism of water flow works because of water potential (water flows from high to low potential), and the rules of simple diffusion.

Consider the following events occurring during mass flow [pressure flow] of phloem sap at the source. The initial events are given in correct chronological sequence. But some of the statements carry mistakes regarding the principles of the process. Identify them:
I. The sucrose is passively transported to the companion cells of the smallest veins in the leaves.
II. The sucrose is actively transported from the companion cells to the sieve tube elements.
III. Water moves by osmosis from the nearby xylem in the same leaf vein.
IV. Hydrostatic pressure moves the sucrose and other substances through the sieve tube cells, towards a sink.
1. I and II only
2. III and IV only
3. I, II and III only
4. I, II, III and IV

In classic experiments on the translocation of organic solutes performed by the Italian anatomist Marcello Malpighi in 1686, the bark of a tree was removed in a ring around the trunk. This experiment, called girdling, was also done by T. G. Mason and E. J. Maskell in 1928. The following were the observations:
I. It has no immediate effect on transpiration.
II. Sugars accumulate above the girdle—that is, on the side toward the leaves—and are depleted below the treated region.
What conclusion/s can be drawn from the above observations?
A: Water moves in the xylem, interior to the bark.
B: Sugar is transported in the bark of the tree and that the sieve elements are the cellular channels of sugar transport.

Trace the correct path of water from the soil through the plant to the atmosphere:

Closure of stomata occurs as the guard cells:
1. lose water.
2. begin photosynthesis reducing internal ${\mathrm{CO}}_2$ concentration.
3. pick up chloride ions.
4. gain potassium ions.