Quiz Chapter 4: Transport in Plants

1. Which forces maintain a continuous, unbroken column of water in narrow xylem vessels during transpiration?

1. Gravity and root pressure
2. Cohesion between water molecules and adhesion to xylem walls
3. Active transport and endosmosis
4. Phloem mass flow and stomatal resistance

2. Which plant species is commonly used in phytoremediation to absorb heavy metals and radioactive pollutants from soil?

1. Helianthus annuus (Sunflower)
2. Cuscuta sp. (Dodder)
3. Asplenium nidus (Bird's nest fern)
4. Nepenthes sp. (Pitcher plant)

3. Which structural modification enables xylem vessel elements to withstand negative pressure without collapsing?

1. Suberin rings in the middle lamella
2. Lignified secondary cell walls
3. Perforated sieve plates with companion cells
4. Thick waxy cutin layers

4. What is the function of aquatic plants like Water Hyacinth (Eichhornia crassipes) in phytoremediation?

1. Absorbing heavy metals and pollutants from contaminated aquatic ecosystems
2. Releasing high concentrations of toxic methane gas into water
3. Consuming aquatic animal larvae through parasitic roots
4. Increasing water salinity to eliminate bacteria

5. How does water move from cell to cell via the symplast pathway in root cortex cells?

1. By moving along external cell walls only
2. Through cytoplasmic connections called plasmodesmata
3. Via active transport protein pumps in cutin layers
4. By bulk flow driven by mechanical contraction

6. Where does sucrose unloading occur according to the mass flow hypothesis?

1. At photosynthetic leaf mesophyll cells
2. At sink regions such as developing fruits, roots, and tubers
3. At the Casparian strip in endodermal cells
4. Inside xylem vessel lumens

7. Under which conditions is guttation most likely to occur?

1. Hot, windy, and dry sunny afternoon
2. Cool, highly humid night with moist soil
3. Freezing winter conditions with dry air
4. Bright daylight with fully open stomata

8. During phloem loading, what occurs immediately after sucrose is actively loaded into sieve tube elements at the source?

1. Water potential in sieve tubes drops, causing water to enter from xylem by osmosis.
2. Hydrostatic pressure in sieve tubes decreases to zero.
3. Stomata close instantly to prevent water vapor loss.
4. Phloem sap freezes and forms solid starch granules.

9. What phenomenon causes droplets of water to exude from hydathodes at leaf margins?

1. Transpiration
2. Guttation
3. Plasmolysis
4. Translocation

10. What function does the Casparian strip serve in the root endodermis?

1. It blocks the apoplast pathway, forcing water and ions through the symplast pathway.
2. It secretes digestive enzymes into soil space.
3. It accelerates water uptake via capillary action.
4. It prevents transpiration loss from root epidermis.