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Leaves

Leaves. Horticulture 1. What are the functions of leaves?. Capture light Exchange gases Provide a site for photosynthesis Some leaves store food and water Some form new plants and provide support. Why does a plant need photosynthesis?. “PHOTO” means light

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Leaves

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  1. Leaves Horticulture 1

  2. What are the functions of leaves? • Capture light • Exchange gases • Provide a site for photosynthesis • Some leaves store food and water • Some form new plants and provide support

  3. Why does a plant need photosynthesis? • “PHOTO” means light • “SYNTHESIS” means to make or form something from • SO….Photosynthesis is a plant making something (food) from light.

  4. Photosynthesis definition: • a process by which plants combine water and carbon dioxide in the presence of chlorophyll and sunlight and produce carbohydrates and release oxygen.

  5. Why is photosynthesis important? • Light is the most important source of energy for living things. Photosynthesis converts light into nutrients that can be used by plants and animals. • Releases oxygen

  6. Recipe for Photosynthesis • 6CO2 + 12H2O sunlight > 6O 2 + C6 H12O 6 + 6H2 OOr in English= Carbon Dioxide + Water in Sunlight => Oxygen + Sugars/Food + Water

  7. There are two parts of photosynthesis--the light and dark reactions. • The light reactions produce chemical energy from light. • The dark reactions convert carbon dioxide into carbohydrates.

  8. Leaves & gas exchange • Oxygen, Carbon Dioxide, and Water exchanged from Stomata • Pores (stomata) open in day to transpire H2O and allow gases to enter • Close during dry conditions to prevent H2O loss.

  9. 1. Leaves : External Parts A. Petiole- leaf stalk or part that connects leaf to stem. Petiole

  10. B. Blade- the large, flat part of a leaf. C. Midrib- the large center vein. Midrib

  11. D. Veins- the structural framework of leaf. Act like pipes to carry water & nutrients Veins

  12. E. Margin- the edge of leaf. Margin (edge of the leaf)

  13. F. Cutin – fatty (waxy) substance in many plant cell walls & on outer surface of epidermal cell walls - forming a Cuticle – a protective covering on a green leaf that helps hold in moisture (this gives the leaf a “glossy” appearance)

  14. G. Stipule – tiny leaf-like structures at the base of a petioleH. Axil – the angle made by the petiole and the stem of the plant.

  15. Leaves: Internal Parts A. Upper and lower epidermis- skin of the leaf that prevents the loss of too much moisture. B. Stomates- small openings under the leaf for breathing or transpiration (also called: stoma or stomata)

  16. (Internal Parts-continued) C. Guard cells- open and close stomates D. Chloroplasts- small green particles that contain chlorophyll, give leaves their green color and are necessary for photosynthesis

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