Lesson 2: Plant transport Flashcards
What are the features of xylem vessels for it to be adapted for water transport?
Lignin
Pits
Made up of dead hollow cells
How are lignins an adaptation for the xylem?
It binds to cellulose and provides it strength.
How are pits an adaptation for the xylem?
They are regions of cell wall that are thinner with no lignin allowing lateral movement of water to adjacent cells.
How is root pressure generated?
Minerals are actively transported into root hair cells which reduces water potential thus water moves in from the soil via. osmosis.
What are sources and sinks in phloem transport?
Sources: Parts of plants producing or releasing carbon compounds.
Sinks: Uses or stores carbon compounds.
Examples of sources.
Leaves
Roots
Examples of sinks.
Growing tissues
Storage organs
What is translocation?
The process of transporting carbon compounds from sources to sinks.
Stages of translocation.
Phloem loading – Sucrose is actively pumped into the phloem from the source (leaf), creating a high solute concentration.
Water enters from the xylem by osmosis due to low water potential in the phloem.
High hydrostatic pressure is generated in the phloem.
Sap flows toward the sink (root) down a pressure gradient.
Sucrose is actively unloaded into the sink.
Water leaves the phloem and returns to the xylem as the solute concentration decreases.
Companion cells assist with active transport throughout this process.
Outline the adaptations of phloem sieve tubes for translocation.
Lack many organelles - more space for transport.
Connected by sieve plates - walls with pores so sap can flow through.
Outline the location and adaptations of phloem companion cells for translocation.
Location: runs alongside the STE.
Many mitochondrias - ATP for active transport.
