Transport in Plants MCQs

Analyze the functional aspects of mycorrhizal associations:

I. Mycorrhizae represent a mutualistic symbiosis where fungal hyphae absorb water and mineral ions (especially phosphorus) from the soil.
II. Fungal hyphae have a high surface-to-volume ratio, allowing them to access a larger volume of soil than root hairs alone.
III. The host plant roots provide sugars and nitrogen-containing organic compounds to the fungus.
IV. Pinus seeds can germinate and establish successfully even without the presence of mycorrhizae.

Which of the above statements are correct?

Examine the properties of cytoplasmic streaming in plant cells:

I. Cytoplasmic streaming is a passive, entropy-driven process that requires no cellular energy.
II. It is an active metabolic phenomenon that can assist the symplastic movement of water and solutes.
III. Cytoplasmic streaming is visible as the circulation of chloroplasts in Hydrilla leaves.
IV. All long-distance transport in plants is achieved through cytoplasmic streaming.

Which of the above statements are correct?

Study these statements comparing positive and negative transport pressures:

I. Root pressure is a positive hydrostatic pressure, while transpiration pull is a negative tension in the xylem.
II. Root pressure is the main driving force that lifts water to the top of tall trees during peak transpiration.
III. Guttation occurs when high root pressure forces liquid water out of specialized vein endings during periods of high humidity and low transpiration.
IV. The major contribution of root pressure in tall trees is to re-establish broken chains of water molecules in the xylem.

Which of the above statements are correct?

Consider these statements regarding the physical stages of plasmolysis:

I. During plasmolysis, water is first lost from the vacuole and then from the cytoplasm.
II. When a plant cell is fully plasmolysed, the space between the cell wall and the shrunken protoplast is occupied by the hypertonic external solution.
III. Plasmolysis occurs when a plant cell is placed in an isotonic solution.
IV. The process of plasmolysis is usually reversible when the cells are placed in a hypotonic solution.

Which of the above statements are correct?

Review these statements concerning imbibition in plants:

I. Imbibition is a type of active transport requiring metabolic energy.
II. For imbibition to occur, there must be a water potential gradient and physical affinity between the adsorbant and liquid.
III. Imbibition is accompanied by a massive increase in volume and can generate immense physical pressure.
IV. Imbibition pressure is what enables emerging seedlings to break through and emerge from the soil.

Which of the above statements are correct?

Three adjacent plant cells (A, B, and C) have the following potentials:

Cell A: Ψ_s = -10 bars, Ψ_p = +4 bars.
Cell B: Ψ_s = -8 bars, Ψ_p = +3 bars.
Cell C: Ψ_s = -12 bars, Ψ_p = +5 bars.

I. The water potential of Cell B is higher than Cell A.
II. Water will show a net flow from Cell B to Cell A, and from Cell A to Cell C.
III. Cell C has the highest water potential among the three cells.
IV. At equilibrium, all three cells will have the same water potential.

Which of the above statements are correct?

Examine these statements about the transport barriers of a plant cell:

I. The cell wall is freely permeable to water and solutes, presenting no barrier to molecular movement.
II. The plasma membrane is selectively permeable, regulating the transport of specific molecules and ions.
III. The vacuolar membrane (tonoplast) is freely permeable, allowing sap contents to freely mix with the cytoplasm.
IV. Together, the cell membrane and the tonoplast are the major determinants of molecular movement into or out of a plant cell.

Which of the above statements are correct?

Study these statements regarding facilitated transport modes:

I. Symport is a facilitated transport mechanism where two molecules cross the membrane in the same direction.
II. Antiport is a mechanism where two molecules cross the membrane in opposite directions simultaneously.
III. Uniport is a passive transport mechanism that moves a single solute molecule across the membrane independent of other molecules.
IV. All three modes—symport, antiport, and uniport—require active expenditure of ATP to function.

Which of the above statements are correct?

Review these statements concerning membrane pores and water channels:

I. Aquaporins are water-conducting proteins that form channels specifically for the passive movement of water.
II. A water channel in a plant cell membrane is made of eight structurally identical types of aquaporin proteins.
III. Porins form huge pores in the outer membranes of plastids, mitochondria, and some bacteria.
IV. Porins are spacious enough to allow molecules up to the size of small proteins to pass through.

Which of the above statements are correct?

Examine the leaf anatomical factors that affect transpiration rates:

I. Dicotyledonous leaves are typically dorsiventral and have a greater density of stomata on their upper epidermis.
II. Monocotyledonous leaves are typically isobilateral and have a roughly equal stomatal count on both surfaces.
III. Plant factors like leaf canopy structure and the water status of the plant directly affect the rate of transpiration.
IV. High relative humidity in the ambient atmosphere increases the overall rate of transpiration.

Which of the above statements are correct?