3.1.3: Transport In Plants Flashcards
What are hydrophytes?
Plants which live in or on water and require adaptations to survive in an excess of water.
Examples include water lilies, which grow on the surface of the water.
What adaptations do hydrophytes have?
- Short roots
- Very thin to no waxy cuticles
- Stomata permanently open on the top surface of the leaf
- Large, wide leaves on the surface of the water
These adaptations help prevent water retention and ensure efficient water loss while maximizing light absorption for photosynthesis.
What is the mass flow hypothesis?
A theory explaining how organic substances, such as sucrose, move from the leaves (source) to respiring cells (sink).
The source is where the substance is produced, and the sink is where it is used.
What happens to sucrose at the source cell?
Sucrose lowers the water potential of the source cell, causing water to enter by osmosis, increasing hydrostatic pressure.
This process facilitates the movement of substances through the plant.
What occurs at the sink cell in the mass flow hypothesis?
The respiring cell uses up sucrose, resulting in a more positive water potential, causing water to leave the sink cell by osmosis.
This decreases the hydrostatic pressure in the sink cell.
What is the relationship between hydrostatic pressure in source and sink cells?
The source cell has a higher hydrostatic pressure than the sink cell, forcing the solution towards the sink cell via the phloem.
This pressure difference is crucial for the movement of organic substances.
Fill in the blank: The site of production in the mass flow hypothesis is called the _______.
[source]
Fill in the blank: The site of use in the mass flow hypothesis is called the _______.
[sink]
True or False: Xylem is involved in the transport of organic substances in plants.
False
Phloem is responsible for transporting organic substances, while xylem primarily transports water and minerals.
