Unit 7 Chapter 23 Plant Structure and Function

Typical plant cell

Plant Tissues 1) Dermal Tissue For covering and protection, and controlling water loss Examples: epidermis, including cuticle of leaves, guard cells & stomata

Plant Tissues 2) Vascular tissue For transport of food, minerals and water Examples: Xylem (for transporting upward from roots) Phloem (for transporting downward from leaves) Phloem Xylem

Plant Tissues 3) Ground tissue cortex 3) Ground tissue For storage, food production, strengthening and support Examples: cortex, pith, mesophyll pith

Plant Tissues 4) Meristematic tissue For production of new cells Apical Meristem of Shoot 4) Meristematic tissue For production of new cells Examples: growing tips in roots and stems (shoots)

Roots To anchor, absorb, and conduct Types of root systems: 1) taproot One main root with branches Ex: carrot 2) fibrous Many small branching roots Ex: grass

Root Structure 1) Root cap Protective covering of root tip 2) Apical Meristem Region of cell division (where mitosis occurs)

Root Structure 3) Epidermis cortex 3) Epidermis May contain root hairs for increasing surface area 4) Cortex Ground tissue for storage of food and water

Root Structure 5) Endodermis Waterproof cells that control flow of water into vascular tissue 6) Pericycle Produces lateral roots

Root Structure 7) Xylem (star-shaped center) Transports water upward 8) Phloem (between rays of star) Transport food downward

Stems To support, conduct, and store Arrangement of Vascular Bundles: Monocots Randomly scattered Dicots Radially arranged Can you classify these stems?

Woody stems Bark Wood Pith (young stems) Composed of cork, phloem, & vascular cambium Wood Composed entirely of xylem tissue Contains annual growth rings Pith (young stems) Pith

Pith

Translocation The movement of sugars through the phloem, from the source (origin) to the sink (storage area, such as root or fruit)

Leaves For photosynthesis and transpiration 1) Blade (flat green portion) Simple One undivided blade Compound Blade divided into leaflets 2) Petiole (stalk) Contains vascular tissue, attaches to stem

Leaf structure 3) Epidermis Upper epidermis produces waxy cuticle to prevent water loss Lower epidermis contains guard cells & stomata to control water loss cuticle

Leaf structure 4) Mesophyll Photosynthetic tissue made up of palisade & spongy cells 5) Veins Contains xylem & phloem cells

Transpiration Evaporation of water through stomata Plants lose 90% of the water they transport from the roots by transpiration. What happens to the other 10%? When water enters the guard cells, pressure causes them to bow, opening the stoma When water leaves the guard cells, pressure is lost and the cells come together, closing the stoma

Plant hormones Like animals, plants produce hormones to regulate growth & development Hormones are chemicals produced in one part and transported to another to effect a change Examples of plant hormones are Auxin, Gibberellins, Cytokinins, & Ethylene (Without) (With) Gibberellin

Tropic responses in plants Tropism is a plant’s response toward a stimulus, such as gravity (gravitropism), light (phototropism) or touch (thigmotropism) Ex: phototropism is the growth of a plant toward light

Nastic responses in plants Nastic movements are NOT dependent on the direction of the stimulus For example: in a Venus’s fly-trap, the insect triggers sensitive hairs on the surface and the leaf snaps shut