plant structures

• Photosynthetic organism are the main producers of food; they use light energy to build carbohydrates to contribute to most of biomass.
• Glucose:

  • sucrose

  • makes starch to store energy
• Cellulose:

  • in cell sap

  • supports cell walls
• Photosynthesis is endothermic as energy enters from surroundings and products have more energy than reactants.
• Cuticle has waxy coating to precent water loss by evaporation.
• Upper epidermis is transparent so light gets to palisade.
• Palisade cells contain chloroplasts.
• Spongy mesophyll are large air spaces to exchange gases.
• Lower epidermis contains guard cells.
• Guard cells open and close the stomata. In the day, they swell open to allow light to enter the leaf. At night, they close to trap heat and water.
• Stomata:

  • Carbon dioxide diffuses through

  • Broad and flat

  • Large surface area for max light absoprtion

  • Thin so carbon dioxide doesn’t have far to diffuse