Topic 8 Flashcards
(18 cards)
What does the xylem transport?
Water and minerals
What does the phloem transport?
Sugars like sucrose
Describe the position of the xylem and phloem in the leaf
The xylem is on the top of the phloem
Describe the position of the xylem and phloem in the stem
The xylem is on the inside of the stem
Describe the position of the xylem and phloem in the root
The xylem is in the middle in an X shape
The phloem is on the outside of the xylem
Describe the pathway of water through a plant
Root hair cell → Root 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 the diffusion distance
Describe the process of transpiration
Water is lost through the stomata More water is drawn up to replace the lost water
What is the transpiration stream?
The transpiration stream is the flow of water through a plant
Describe transpiration
The evaporation of water from the mesophyll cells that then diffuses out through the stomata
Explain the movement of water through a plant
Travels up the Xylem
How does temperature affect the rate of transpiration?
As the temperature increases, so does the transpiration rate
The molecules have more KE and evaporation happens faster
How does humidity affect the rate of transpiration?
The more humid the air around the plant, the lower the rate of transpiration because there is a less steep concentration gradient
The rate of transpiration increases
How does the wind speed affect the rate of transpiration?
The faster the wind speed, the faster the water is moved away from the plant, creating a steeper gradient and increasing the transpiration rate
What causes wilting?
A lack of water which means the plant cells are not turgid and so the plant is not supported
Describe translocation
Translocation is the movement of sugars and amino acids up or down the phloem from source to sink (with the use of energy)
Define source and sink
Source is where the sugars and amino acids are released and the sink is where they travel to
Give an example of something that can be a source and a sink- explain
Leaves- source in the summer and sink in winter
