Presentation on theme: "Chapter 23 Plant Structure and Function Plant Tissue Vascular Plants have four basic types of tissue 1.Vascular tissue 2.Ground tissue 3.Epidermis 4.Meristematic."— Presentation transcript:
Plant Tissue Vascular Plants have four basic types of tissue 1.Vascular tissue 2.Ground tissue 3.Epidermis 4.Meristematic Tissue
Plant Tissue Vascular Tissue Xylem – transports water and minerals Phloem – transports sugars Ground tissue – surrounds the vascular tissue some store water or sugars, others lend support to the plant Epidermis – layer of flattened cells secrete the waxy cuticle Meristems – regions of actively dividing cells found in ares that are growing
ROOTS Roots - anchor plant to the ground and absorb water and minerals. Make up 1/3 of weight of a plant. Absorption actually takes place in the root hairs. Increases the surface area of a root. Growth of a root takes place in a root cap by cell division. Some roots have specialized functions like food or water storage.
STEMS Shoots - made up of the stem and leaves. In some cases, it also includes the flowers and fruits. Stems support the leaves so they can capture sunlight. Stems also connect the roots to the leaves and contain the vascular tissue needed for transport of water and minerals. Stems can be modified for storage.
LEAVES Leaves are the main sites for photosynthesis. Leaves contain chloroplasts which contain the chlorophyll needed for photosynthesis.
LEAVES Thin and Flat – advantageous for photosynthesis Cuticle - leaves contain a waxy outer layer that prevents it from losing too much water. Stomata – tiny pores that allow carbon dioxide to enter and water and oxygen to exit
LEAVES Inside a leaf are layers of photosynthetic cells Bundles of vascular tissue (veins in leaves) Xylem Phloem
How Plants Function Transpiration - Water Movement in Plants occurs in Xylem Translocation - Food Movement in Plants Occurs in phloem Growth and Plants Hormones Other (Sunlight, Temperature, and Gravity)
Water Movement in Plants Water travels from roots trunk/stem leaves Travels to all the parts of the plant through the xylem. Direct result of Transpiration in Plants
Transpiration The loss of water vapor from a plant through its stomata More than 90% of water entering plant passes through plant and evaporates through the stomata
Stomata and Transpiration Stomata - Specialized pores located in plant cuticle that enables plant to exchange gases with the atmosphere
Stomata and Transpiration Two guard cells surround the stomatal pore and control the opening and closing of the stomata.
The Role of Stomata Evaporation : Helps cool the plant but sometimes the transpiration is so rapid that the loss of water begins to exceed the intake and the stomata may close to prevent wilting. Gas Exchange: The plant must open stomatal pore during photosynthesis to allow CO 2 inside the plant and O 2 out.
Transpirational Pull As transpiration takes place, it creates a “pull or tension” drawing water from the xylem and ultimately from the soil When plants transpire, the water potential in cells adjacent to the stomata drop because they lose water into the atmosphere. This cause a chain reaction which pulls water from other cells eventually pulling water from the xylem, root, and soil.
Translocation The transport of nutrients (food) formed during photosynthesis within the phloem to all parts of the plant.
Plant Growth Primary Growth – Growth that lengthens Meristems – region where plants grow using cell division, this growth occurs in the tips of roots and shoots and enable the plant to grow in length Secondary Growth - Growth that thickens Woody plants (trees and shrubs) thicken by producing xylem and phloem. Rings of a tree are layers of xylem and phloem
Plant Hormones Auxin - produced in the tips of stems, causes cell walls to become more flexible If a stimulus causes auxin to concentrate more on one side of a stem, the cells on that side will elongate. Thus, the stem grows toward light.
Plant Hormones Gibberellin Stimulate cell division, elongation, and the sprouting of seeds. Ethylene Stimulates fruit ripening. Also promotes the dropping of leaves, flowers, and fruits.
Other Factors - Tropism Photoperiodism – the response of plants to periods of light and dark Geotropism – response of plant to gravity Helps plant determine which way to grow roots. Thigmotropism – response of plants to touch Helps climbing plants find support structures