PLANT SCIENCE BURN GM PLANT SCIENCE Plant Structure
PLANT SCIENCE BURÇİN GÜMÜŞ
PLANT SCIENCE Plant Structure & Growth Dicotyledonous- Monocotyledonous Plants Parts of a plant Tissues in the Plant Modifications Transport in Angiospermophytes Reproduction in Angiospermophytes
Gymnosperms Vascular plants that produce seeds – no flowers and fruits Gymnosperm means ‘naked seeds’ Conifers Cycads Gingko Gnetales Seeds in cones or hard berries
Life Cycle of a Gymnosperm Sapling Seeds Tree Cone
Angiosperms Vascular plants that produce flowers that can produce seeds or fruits Seeds in fruit Two types of angiosperms Dicotyledonous Monocotyledonous
Life Cycle of an Angiosperm
Monocots vs. Dicots
Monocotyledone Plants
Monocot vs. Dicot
Parts of a Plant
Parts of a Plant Leaves Stems Roots Flowers Petioles Auxiliary Bud Terminal Bud
Leaves Function Manufactures food for the plant by using light energy. (Photosynthesis) Transpiration releasing water and oxygen in exchange for carbon dioxide Useful for identification of the plant Margin (leaf edge) Shape Arrangement
What are the external parts of a leaf? Blade Petiole Margin Vein Midrib
External parts of a leaf Blade – flat part for catching sunlight Petiole – stem-like structure to hold leaf Margin – edge of leaf Vein – conducts water and sugars Midrib – central vein that connects to the stem
What are the internal parts of a leaf? Cuticle Epidermis Palisade Mesophyll Spongy Mesophyll Guard Cells Stoma Vascular Bundles (Phloem-Xylem)
Internal parts of a plant Epidermis – protects leaf Cuticle – prevents water loss Palisade Mesophyll – contain a lot of chloroplasts Spongy Mesophyll – surfaces for gas exchange
Internal parts of a plant Guard Cells – transpiration and allowing for gas exchange Stoma – natural openings and allowing for gas exchange Vascular bundles – transport water to the leaf (xylem), starch away (phloem)
Stems Function Supports other plant parts such as Leaves • Flowers Fruit Contains the vascular tissue that transport the subtances around the plant
Stems • Two types of above ground stems Woody Herbaceous • Herbaceous stems that are usually soft, green and flexible • Woody stems generally hard
Woody or Herbaceous?
Tissue types of the plant stem Epidermis Cortex Tissue Vascular Bundle Xylem Floem Cambium Pith Tissue
Roots Function Anchor the plant Absorb water & minerals for plant use Produce hormones that stimulate growth
Other roots eventually branch out from the primary root. These are called secondary or lateral roots.
Two types of root systems Fibrous Tap Root
Fibrous or Tap Root?
Modifications of roots, stems and leaves for different functions Stem modifications Bulbs: Onions & Lilies Short vertical underground stems. Many fleshy highly modified leaves for the storage of nutrient.
Stem Modifications The horizontal stems called runners (stolon) spread out from the main body of the plant. At point the stem touches the ground new roots form. The horizontal stems are often an adaptation to finding water.
Stem Modification Leaves are reduced to spines to prevent water loss in transpiration. The stem is enlarged for the storage of water. The stem carries out photosynthesis.
Spines are the leaves
Root tip modification Stem Tuber/ Potato The potato is an underground modification of the root tip. The 'eaten potato' contains the carbohydrate and protein stores for the growth. The 'eyes' are in fact axillary buds.
Tap Root Modification Function: Storage of water Carrot plants are often associated with very sandy soils. The root modification allows the storage of water in the cortex and central stele.
Flowers Function Contain the sexual organs for the plant Produce seeds & fruit
Parts of the flower Sepals Petals Reproductive Organ Male –Stamen Female - Pistile
Parts of the Flower Sepals Outer covering of the flower bud Protects the stamens and pistils when flower is in bud stage Collectively known as the calyx
Parts of the Flower Petals Brightly colored Protects stamen & pistils Attracts pollinating insects Collectively called the corolla
Parts of the Flower Male reproductive part (Stamen) Anther Manufactures pollen Filament Supports the anther Pollen Male sexual reproductive cell
Parts of the Flower Female reproductive part (Pistil) Ovary Enlarged portion at base of pistil. Produces ovules which develop into seeds Stigma Receives the pollen Style Connects the stigma with the ovary. Supports the stigma so that it can be pollinated.
Plant Growth - Meristems Plants only grow at the meristems: undifferentiated cells – like stem cells in animals Embriyonic regions These can be apical or lateral
Apical Meristem Apical meristems are found at the tip of the root and the shoot, adding growth to the plant in these regions. The apical meristems are described as indeterminate , this type of growth tends to add length to root and stem in 'module' or 'units'
Root Apical Meristem (a) Root cap (b) Root apical meristem (c) Ground meristem (d) Protoderm (e) Epidermal tissue of the root (f) Vascular tissue (central stele) Apical Meristem
Lateral Meristem The tissue diagram is a cross section of the stem of the primary plant body There is no additional secondary thickening of the cell walls
Lateral Meristem Lateral meristem is secondary growth adding thickness with this two type tissues Cambium: that produces secondary xylem and phloem Cork Cambium: produces some of the bark layer of a stem
Growth in Plants Growth in plants is brought with cell division at the apical and lateral meristem This growth process is adding length to the stem or root
Auxin Role in Plant Growth Tropism growth movement either toward or away from a directional stimulus Plants’ responses to stimuli can be either positive (towards stimuli) or negative (away from stimuli) Phototropism is the bending-growth towards the unilateral source of light. Auxins are a class of plant growth hormones (growth regulating factor)
Tropism: plants respond to a stimulus
Auxins promote growth by lengthening cells. Produced in coleoptile, protective sheath covering the emerging shoot or root. http: //www. youtube. com/watch? v=4 -2 DZo 2 pp. AY
Auxin Under normal conditions, auxin distributed along the shoot , causing vertical growth
Auxin If photoreceptors in the coleoptile detect a light stimulus from one direction, auxin is moved to the opposite sight of the growing shoot. Because auxins don’t like light
Auxin Irregular distribution of auxin causes increased growth on one side and the plant grows towards the direction of the light Auxin is produced in dark places in the plant
Transport in Angiospermophytes Function of the root Absorption of minerals and water Anchor the plant Contain root hairs that increase surface area for absorption to occur
The extension of the cell wall increases the surface area for the absorption of water and minerals
Transport in Angiospermophytes
Transportation Transport in vascular plants occurs on three scales : Transport of water and solutes by individual cells, such as root hairs Short-distance transport of substances from cell to cell at the levels of tissues and organs Long-distance transport within xylem and phloem at the level of the whole plant Soil solution Root Hair Epidermis Root Cortex Root Xylem
Short-distance movement Movement of water at the cellular level plays a major role in bulk water transport Water can diffuse through cell membranes However, ions and organic compounds rely on membrane-bound transporters -Active or passive mechanisms
Transport Mechanisms Plasmodesma Cell wall Plasma membrane Osmosis Active Proton Pump Outside Cell Passive or Symport Ion Channel Diffusion Sucrose K+ ATP Inside Cell H+ H+
Long-distance movement Caused by transpiration – evaporation from thin films of water in the stomata Occurs because water molecules stick to each other (cohesion) and to the walls of the vessels (adhesion)
Cohesion & Adhesion Cohesion: Water is attracted to water Adhesion: Water is attracted to other substances
Transpiration The loss of water vapour from stomata Functions cooling transportation maintaining turgor pressure
Stomata 90% of water ‘absorbed’ by roots lost through transpiration in leaves Transpiration through stomata, pores in epidermis of leaves
Stomata Transpiration rate regulated by two guard cells surrounding each stoma Guard cells open when water moves into cells by osmosis
Stomata
Xerophyte Adaptations Xerophytes are plants adapted to arid climates They have various leaf modifications that reduce the rate of transpiration The stomata of xerophytes Are concentrated on the lower leaf surface Are often located in depressions that shelter the pores from the dry wind
Propagation What is Propagation? Increasing the number of a plant species or reproduction of a species Two types of propagation Sexual use of seed for reproducing plants only way to obtain new varieties Asexual vegetative
Seed Parts of the seed Seed Coat offers protection Endosperm supplies food for the seed Embryo is the young plant
Germination The seed starts to sprout and grow Requires four environmental factors: 1. 2. 3. 4. Water Air Light Temperature
Sexual Propagation The use of seed for reproducing plants. Allows the most variation of any propagation method. Only way to obtain new varieties and increase hybrid vigor of the plants. Less expensive & quicker than other methods. Occurs through pollination.
Asexual Propagation Use of a part of a plant for reproducing plants. Also called vegetative propagation. The new plant is an exact duplication of the parent plant. There a lot of types of asexual propagation: cuttings layering division or separation budding grafting tissue culture
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