The Structure and Function of Xylem and Phloem

(c) describe, with the aid of diagrams and photographs, the structure and function of xylem vessels, sieve tube elements and companion cells;

Vascular bundle...

Notes pgs 70-71...

Answer qus 1-5 pg 71 AS OCR

• Compare the function, what is transported, what part of the plant they are found in, any additional functions, their structure, and the nature of the tissue (alive or dead)

• (c) describe, with the aid of diagrams and photographs, the structure and function of xylem vessels, sieve tube elements and companion cells;

Improve this chart Phloem Xylem

Function:Transportation of food and nutrients from leaves to storage organs and growing parts of plant.

Water and mineral transport from roots to aerial parts of the plant.

Movement:Bidirectional (Moves up or down the plant's stem from "source to sink")

Unidirectional (Moves up the plant's stem)

Occurrence: Roots, stems and leaves Roots, stems and leaves

Additional Functions: Forms vascular bundles with xylem

Forms vascular bundles with phloem and gives mechanical strength to plant due to presence of lignified cells.

Structure: Tubular with soft walled cells

Tubular with hard walled cells

Elements:Sieve tubes, companion cells, phloem parenchyma, intermediary cells, two tube flow

Xylem vessels , xylem parenchyma

Nature of tissue: Living tissue Non living tissue at maturity

Summary...

• The vascular tissue in a leaf forms a network of bundles that finally merge to form one central (1) which runs into the stalk of the leaf that is also called the (2). The vascular tissue found nearest to the upper surface of the leaf is (3). In stems, the vascular tissue nearest the outside of the stem is (4). Inside this tissue is a layer of dividing tissue called (5) and outside it there is often a region of supporting tissue called (6). The vascular tissue in stems forms a cylinder towards the outer edge as this arrangement best resists the (7) forces that stems are subjected to. In roots, the vascular tissue is central in order to resist the (8) forces experienced by the roots.

Missing words…

1. Vein2. Midrib3. Xylem4. Phloem5. Cambium (meristem)6. Parenchyma7. Shearing/bending8. Pulling