4.2.2 - Plant Stems Flashcards
What Are The Function Of The Xylem Tissues In A Plant?
(2 Points)
~ Transports dissolved minerals and water around the plant.
~ Structural support.
What Do The Walls Of The Xylem Vessels Contain?
Lignin.
What Does Lignin Enable?
The vessels to withstand the pressure created by the moving column of water.
What Are Xylem Vessels Formed By?
Dead cells with open ends.
What Don’t Xylem Vessels Contain & Why?
(2 Points)
~ No cytoplasm or any organelles.
~ So they don’t slow down the flow of water.
What Are The ‘Pits’?
Small regions in the walls of the xylem that are not lignified.
What Do They Pits Allow In Terms Of The Xylem Vessel?
Lateral movement of water and minerals between xylem vessels.
Do Xylem Vessels Have End Plates?
No.
What Do Sclerenchyma Fibres Provide?
Structural support.
What Are The Sclerenchyma Fibres Made Up Of?
Dead cells with a hollow lumen and end walls.
What Do The Walls Of The Sclerenchyma Fibres Contain?
(2 Points)
~ Lignin but don’t have pits.
~ More cellulose compared to other plant cells.
What Is The Function Of The Phloem Tissue?
~ Transport food substances and nutrients from leaves to storage organs.
What Direction Does The Transport Of The Substances In Phloem Tissues Occur?
Up and down the plant, which is known as translocation.
Do Phloem Tissues Have Any Structural Support In The Plant?
No.
What Are Phloem Tissues Made Up Of?
Living cells.
Phloem Tissue Is Made Up Of Many Different Cell Types, What Are These Cell Types?
(3 Points)
~ Sieve tube elements.
~ Companion cells.
~ Parenchyma cells.
What Are Parenchyma Cells?
Helps with plant storage.
What Do The Sieve Tube Elements Do?
Line up end to end to form a continuous tube.
What Is The Structure Of Sieve Tube Elements?
(4 Points)
~ Have sieve plates with sieve pores.
~ Cellulose cell wall.
~ No nucleus, vacuole or ribosomes.
~ Thin cytoplasm.
One Structure Of The Sieve Tube Elements Is ‘Have Sieve Plates With Sieve Pores’, What Does This Mean?
Allows for the continuous movement of the organic compounds.
One Structure Of The Sieve Tube Elements Is ‘Cellulose Cell Wall’, What Does This Mean?
Strengthens the wall to withstand high pressure.
One Structure Of The Sieve Tube Elements Is ‘No Nucleus, Vacuole Or Ribosomes’, What Does This Mean?
Maximises the space for translocation.
One Structure Of The Sieve Tube Elements Is ‘Thin Cytoplasm’, What Does This Mean?
Reduces friction to facilitate the movement of the substances.
What Are Companion Cells Associated With?
Sieve tube elements.
What Is The Role Of A Companion Cell?
(2 Points)
~ Controls the metabolism of their associated sieve tube member.
~ They play a role in loading and unloading of sugars into the sieve tube elements.
What Is The Structure Of Companion Cells?
(4 Points)
~ Nucleus and other organelles present.
~ Transport proteins in plasma membrane.
~ Large numbers of mitochondria.
~ Plasmodesmata.
One Structure Of The Companion Cell Is ‘Nucleus & Other Organelles Present’, What Does This Mean?
Provides metabolic support to sieve tube elements and helps with the loading and unloading of substances.
One Structure Of The Companion Cell Is ‘Transport Proteins In Plasma Membrane’, What Does This Mean?
Moves substances into and out of the sieve tube elements.
One Structure Of The Companion Cell Is ‘Large Numbers Of Mitochondria’, What Does This Mean?
To provide ATP for the active transport of substances into or out of the companion cell.
One Structure Of The Companion Cell Is ‘Plasmodesmata’, What Does This Mean?
Link to the sieve tube elements to allow for substances to move between them.
In A Stem Where Are The Xylem Vessels Located?
Middle of the stem.
In A Stem Where Are The Phloem Tissues Located?
Towards the outside of the stem.
