BIOLOGY 13th Edition Raven

BIOLOGY 13 th Edition Raven. Chapter 35 Plant Form.

Introduction. The plant kingdom has great diversity, it includes many diverse plant species. Vascular plants (known as tracheophytes) are a large group of plants that conduct nutrients from below ground and above ground (plants with a vascular tissue). From below ground : conduct H 2 O and minerals From above ground : conduct CO 2 and light.

Plants consist of organs , tissues , and cells: A cell is the fundamental unit of life A tissue is a group of cells consisting of one or more cell types that together perform a specialized function An organ consists of several types of tissues that together carry out particular functions..

Three basic organs of a plant are: roots , stem , and leaves organized into:.

Vascular plants consist of two organ systems: 1- Root system Anchors the plant in the soil Used to absorb water and ions. 2- Shoot system (above the ground) Consists of supporting stems, photosynthetic leaves, and reproductive flowers. Repetitive units consisting of internode, node, leaf, and axillary bud..

The plant body is composed of a root and shoot system (see appendix).

The Stem consists of: Nodes : points where leaves are attached Internodes : the stem segments between nodes Apical bud (terminal bud) : growing shoot tip that causes elongation of plant Axillary buds (lateral buds): structures that have the potential to develop into branches with leaves, thorn, or flower (floral buds).

Vascular plants consist of 3 types of tissues. Plant cell types can be distinguished based on: Size of vacuoles. Living or not at maturity. Thickness of secretions found in their cellulose cell walls. Some cells have only a primary cell wall of cellulose, synthesized at the protoplast (entire cell excluding cell wall) . Some cells have more heavily reinforced cell walls with multiple layers of cellulose..

Synthesis of a plant cell wall. The plant cell wall is built as parallel layers of cellulose fibers are synthesized (see appendix).

Plants have only 3 basic tissue types: Dermal: primarily epidermis ; is one cell layer thick in most plants, and forms an outer protective covering for the plant Ground :function in storage, photosynthesis, and secretion. Vascular : conducts fluids and dissolved substances. Because each of these tissues extends through the root and shoot systems, they are called tissue systems ..

New Growth Occurs at Meristems. When a meristem cell divides, one of the daughter cells is a differentiated cell while the second is a meristem cell that can divide again (see appendix).

Located at tips of stems and roots Give rise to primary tissues which are collectively called the primary plant body Apical meristems composed of delicate cells that need protection Root cap protects root apical meristem. Leaf primordia shelter shoot apical meristem..

Shoot Apical Meristems. Primary Growth (growth in length) Meristematic cells are packed closely together without intercellular SShoot apical me Primary me Mature tissu Leaf Dermal Ground Time Cell division Daughter cell Cell division Growing cells Differentiated cells Youngest differentiated Older differentiated.

Root Apical Meristems. At the root tip, all three tissue systems originate at the root apical meristem, which is covered by the root cap..

Found in plants that exhibit secondary growth (width/ girth/ diameter) Give rise to secondary tissues which are collectively called the secondary plant body Woody plants have two types The vascular cambium adds layers of vascular tissue called secondary xylem (wood) and secondary phloem The cork cambium produces outer bark ( écorce , لحاء ); replaces the epidermis with periderm, which is thicker and tougher.

Apical meristems produce the primary plant body. In some plants, the lateral meristems produce an increase in the girth of a plant. This type of growth is secondary because the lateral meristems were not directly produced by apical meristems..

Vascular plants:. Cells Meristems Differentiated cells Tissues Dermal Vascular Roots Stem Organs Ground Systems Shoot Leaves Root.

Meristems (stem cells):. Meristem Apical Lateral.

Meristems (stem cells):. Apical Meristem Protoderm Ground meristem Procambium.

Plant Tissues after differentiation. 3 main types of tissue Dermal (blue) On external surfaces that serves a protective function. Ground (yellow) Forms several different internal tissue types and can participate in photosynthesis, serve a storage function, or provide structural support. Vascular (purple) Conducts water and nutrients..

Dermal Tissue. Forms the epidermis One cell layer thick in most plants Forms the outer protective covering of the plant Covered with a waxy cutin layer constituting the cuticle Contains special cells, including guard cells, trichomes, and root hairs.

Stomata are openings in the epidermis between two guard cells that regulate the size of the opening (see appendix).

Trichomes. Cellular or multicellular hairlike outgrowths of the epidermis Occur frequently on stems, leaves, and reproductive organs Reduce evaporation by covering stomatal openings Protect leaves from high-intensity light and ultraviolet radiation Can buffer against temperature fluctuations Can greatly vary in form: May be a single cell or multicellular Some are glandular, secreting substances that prevent herbivory.