Transport In Plants Flashcards
(30 cards)
What is the apoplast pathway
When water moves along the cellulose micro fibrils of the cell wall
What is the symplast pathway
When water moves by osmosis from cell to cell via the plasmodesmata in the cytoplasm
What is the endodermis
The outside layer of the stele
What is the epidermis
The outer layer of the root
What is the stele
The central vascular cylinder
What is the Cortex
Undifferentiated cells between epidermis and endodermis
What is inside of the cross section of a stem
Vascular bundles with the xylem is the inside and the phloem on the outside
With the cambium in the middle
What is inside the cross section of a root
Central stele consisting of the xylem dominating the phloem
What helps the xylem transport water efficiently
No cell contents for ideal water transport
No end walls to create a hollow tube
Dead when fully formed
Thick lignin within the secondary cell wall to prevent water loss and give support
What is the metaxylem
Mature xylem found in permanent plant structures
Reticulated and pitted lignin found in metaxylem
What is protoxylem
First formed xylem
Found in short lived structure
Spiral and annular lignin found in protoxylem to allow it to stretch and grow
What is the phloem made up of?
Many different cell types
Mainly sieve tube elements to transport sucrose
Parenchyma cells
Is phloem tissue living or not
Living and it has an active process requiring energy
What is a sieve tube elements structure
Sieve tube elements aligned end to end to form a sieve tube
They have end walls perforated with pores to form sieve plates
Have microtubules that extend between sieve elements and pass through sieve pores
What are sieve plate elements closely associated with
Companion cells one or more
What is within the companion cell
Dense cytoplasm rich in mitochondria and other organelles to have a high metabolic rate
How are companion cells linked to the sieve tube elements
Through plasmodesmata
Adaptations of root hair cells
Have large surface area to facilitate the uptake of water
Thin exchange surface (cell surface membrane)
How does water enter a root hair cell
By osmosis as the water soil has a less negative water potential than the root due to the sugars present in the cell and so water moves from the soil to the root
Once the water enters the root how does it move across the cell cortex
Through the apoplast pathway or the symplast pathway
Describe the apoplast pathway
Water moves along the cellulose microfibres of the cell wall
The microfibres are arranged parallel in the cell wall to allow water to pass easily between the layers not, through them
What is an advantage of the apoplast pathway
Limited resistance to water movement
Describe the symplast pathway
Water moves by osmosis from cell to cell across the cortex
Involves a negative water concentration gradient
The water moves from cell to cell through plasmodesmata
