Transport in Plants Flashcards
What do the xylem and phloem transport?
Xylem: water and minerals
Phloem: sugar like sucrose
Describe the position of the xylem and phloem in a leaf.
- The xylem is on top of the phloem
- Branched veins
Describe the position of the xylem and phloem in a stem.
- Veins arranged in a ring
- Phloem outside; xylem near the center
Describe the position of the xylem and phloem in a root.
- Tissues in the center of the root
- xylem as an ‘X’ in the center
- Phloem around it
Describe the pathway of water through a plant
Root hair cell —> cortex cells —> Xylem —> Mesophyll cells
How are root hair cells adapted to their function?
- Long root hair extension to increase surface area for uptake
- Thin membranes to decrease osmosis distance
What is transpiration?
- Loss of water vapor through evaporation at the surfaces of mesophyll cells
- followed by diffusion of water vapor through the stomata to replace the water
Why is water lost from plants?
- Plants have large air spaces in them (stomata)
- Large surface area for evaporation to occur
How does water move up to replace missing water?
- Water evaporates from the leaves creating a negative pressure in the xylem (transpiration pull)
- Water is pulled up the xylem in a column that is held together by cohesion
How do Wind speed, light, and temperature affect the rate of transpiration?
Wind speed: the faster the wind the faster the water vapor is moved away from the plant, creating a steeper gradient for diffusion
Light: The brighter the light, the more the stomata open, making photosynthesis happen more making transpiration happen faster
Temperature: The higher the temperature, the more the Molecules have more KE so evaporation happens faster.
What is wilting and how does it happen?
cells become flaccid because there is a greater rate of transpiration than the rate of water uptake.
What is Translocation?
the movement of sugars and amino acids up or down the phloem from source to sink using energy
