14.3 Structure and Function of Plant Parts
Review… • Functions of vascular tissue: • Xylem: ___________________________________ • Phloem:__________________________________ • Formation of glucose occurs in: _________________ • Why would the rest of the plant require glucose? __________________________________ • During the winter, glucose is stored in the ___________ in the form of _____________. • Glucose is translocated through the plant in the form of___________________. • Absorption of water/minerals occur through the _____________. • Why would a plant need to move water up to the leaves? ____________________.
Major parts of the plant: • Leaves • Stem • Roots
The Leaf • Leaves come in many different shapes, sizes, patterns, and arrangements. • Primary role: convert Sun’s energy into food for the plant through photosynthesis. • Chemical Equation for Photosynthesis: ____________________________________ • For an ecosystem, leaves provide: • Food • Oxygen • Shade • Camouflage • Habitat • Food
Major Parts of the Leaf: • Epidermis • Stoma • Spongy Layer • Vascular tissue • Palisade Cells
1) Epidermis • The external layer of living tissue • Protects interior tissue • Function is similar to human epidermis: skin. • Flat cells fit together like tiles germ-proof barrier. • Repels fungi and bacteria • Cuticle: waxy, non-living layer secreted by epidermis. • Keeps water and gases from entering / leaving leaf (control) BOTH THE CUTICLE & MOST EPIDERMAL CELLS ARE TRANSPARENT. WHY?
2) Stoma • Plural: stomata • Pore-like opening in plant’s epidermis. • Especially numerous on underside of leaf: why? • Permits gas exchange between leaf and environment. • Guard cells: regulate gas exchange by controlling the size of the stomata larger opening: faster CO2 & O2 can be exchanged. • To open stoma: water flows into cells by osmosis cell membranes pushed out. • To close stoma: water flows out of cells by osmosis drop in water pressure causes cells to become flaccid, lose curve, and close space.
3) Spongy Layer • Spongy spaces contain gaseous CO2 and O2, as well as water vapour. • Many water molecules in spongy spaces between cells escape as water vapour through ___________ in the process called ______________________. Plant Transpiration Mini Lab (page 537) Mass of transparent bag: _____________________ # droplets in transparent bag after transpiration: _____ Mass of transparent bag + transpiration water: _______ Complete questions 1 & 2
4) Vascular Tissue • The veins of a leaf are made up of ___________ and ___________, which are bundled together in _______________ bundles. • Dicot: veins arranged in _____________ pattern. • Monocot: veins arranged in ________________ pattern. • Vascular tissue has three fluid-conducting functions • Water __________ the leaf. • Dissolved minerals ________ the leaf. • Dissolved carbohydrates ________ the leaf.
5) Palisade Cells • Long, thin cells underneath epidermis. • Upper end is exposed to incoming light. • Bottom end is exposed to gases of the spongy layer. • Again, what is the chemical equation of photosynthesis? ________________________________________________ • What, then, do you think the major function of palisade cells is? ____________________________.
The Stem • Herbaceous stems: green/flexible. • Must be replanted every year. • Woody stems: brown/rigid • Live for over 100 years. Monocots/Dicots:
Specialized Kinds of Stems: • Stolons • Also called ‘runners’: above-ground and horizontal. • Ex// strawberry. • Rhizomes • Underground, horizontal. • May be long and thin or thick and fleshy. • Enlarged sections are called tubers (potatoes) • Corms • Bulbous, underground structures covered by papery leaves. EITHER WAY, STEMS ARE INCREDIBLY DIVERSE!
The stem’s major function: • Holding leaves up. • Why would leaves be held up? ____________________ • Transportation of material: • Water/dissolved material from ______ to ______. This occurs through _______________. • Food molecules (glucose) transported from the _______ to the rest of the plant. This occurs though ________. • Food molecules (glucose) stored in roots transported to any other part of the plant through ___________.
Thinking Lab: Counting Growth Rings • I hope you printed out the hand-out!
The Root: • Anchors the plant in the soil • Erosion: mainly caused by roots cliffs, roads, driveways. • Different forms of roots: • Fibrous: many slender mini-roots. • Taproot: dominant, large, fleshy, and usually stores glucose. • Carrots, beets, turnips, radishes.
Nutrient Transport Functions of Roots • First function: _______________________ • Second: aid in nutrient transport within the plant. • Absorb water (needed for ___________ • Absorb minerals • Store starch. Root hairs: increase surface area for absorption.
Seatwork/Homework • Read pages 535-538 • Make notes