BIO 02 Lesson 10: Xylem and Phloem

Phloem Transport

Xylem Transport

Two Types of Plant Transport

Xylem Transport

tissue conducts water and dissolved mineral nutrients.

It is composed of columns of vessel cells (tracheids in gymnosperms), stacked one upon another, and fibers.

Vessel cell walls are pitted and allow water passage between the _____ and surrounding tissues.

Mature _____ cells are dead.

Tracheids

tapered elongated cells

- connect to each other through pits

- secondary cell walls strengthened

with lignin

- dead at functional maturity

• Functions

- transport of water plus dissolved

minerals

- support

Vessel Elements

- shorter and wider than tracheids

- possess thinner cell walls than tracheids

- Aligned end-to-end to form long micropipes

- dead at functional maturity

transport of water plus dissolved minerals

- support

Phloem Transport

tissue conducts the food produced by the leaves in a downwards direction to stems and roots (from source to sink).

_____ is composed of sieve tubes, companion cells, and fibers.

The end walls of the sieve tubes are called sieve plates

Sieve-tube Members

- living cells arranged end-to-end to form food-conducting cells of the phloem

- lack lignin in their cell walls

- mature cells lack nuclei and other cellular organelles

- alive at functional maturity

transport products of photosynthesis

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Companion cells

- living cells adjacent to sieve- tube members

- connected to sieve-tube members via plasmodesmata

Sieve plate

-support sieve-tube members

- may assist in sugar loading into sieve-tube members

Fiber Cell

have thick walls. A cluster of fiber cells is called a fiber.

Fibers are associated with the xylem and phloem of both monocots and dicots.

Fibers provide strength and support to xylem and phloem.

TURGOR PRESSURE

the influx of water into the cell causing the plasma membrane to push against the cell wall

WATER POTENTIAL

regulates the transport process in plants

Vascular plants

have xylem and phloem in transport system

Nonvascular plants

they lack xylem and phloem in their structure. Has no vascular tissues.