Lab: How a Plant Gets the Raw Ingredients for Photosynthesis... 1.) In which layer does most of the photosynthesis occur? 2.) What is the likely function of the cuticle? The leaves of plants are its main organs of photosynthesis. Because plants 3.) What is the likely function of the epidermis? need carbon dioxide, water, and sunlight to carry out photosynthesis, the 4.) The vascular tissue can be seen internally as the xylem and phloem and leaf structure is optimized for obtaining all of these reactants. Structures also externally as a such as the chloroplasts, vascular tissues, guard cells and stoma all play a key rule in making photosynthesis happen. Use the textbook Ch. 23 to help Part Guard Cells & Gas Exchange (Leaf Structure) - Ref. p. 597 with this lab. Use the leaf from Part I. Paint a thin film of clear fingernail polish on a small patch of the upper surface of the leaf. Turn the leaf over and repeat with Part I: Leaf Structure - External fingernail polish. Let the polish dry and carefully lift the polish off the leaf Obtain a leaf from the instructor. Look at its structures. Sketch the leaf and with a piece of clear tape. Place the tape on a microscope slide and observe label these structures: blade, stem, veins. the imprints of the guard cells under the microscope. Sketch what you see: Label these structures: guard cell, stoma. Upper Leaf (Mag ) Lower Leaf (Mag ) "-7,111■1 Part II: Leaf Structure - Internal Label the cross section of the leaf. (Text Ref. p. 596) I). Guard cells help the plant exchange gases while at the same time helping it to maintain as it responds to changes in its environment. 2.) Guard cells help regulate opening and closing of stomata in response to changes in pressure within the guard cells. When water pressure within a guard cell is , the guard cell swells because of turgor pressure in the vacuole. This the stoma. When water pressure within the guard cell , the guard cell shrinks, and the stoma 3.) When the guard cells are open, gases are exchanged with the environment. moves into the leaf, and moves out of the leaf. Part IV: Vascular Tissue & Water Transport (Stem Structure) Part V: Photosynthesis/Transpiration & Cycling of Elements Obtain a stalk of celery and a small amount of red water from the teacher. Through gas exchange, photosynthesis, and transpiration, plants play a vital Place the celery, cut end down/leaf end up, into the red water. Let it sit for role in cycling matter through the biosphere. Use the diagrams in Chapter 3 about 10 minutes cr more. Remove the celery from the water and cut a to make sketches of the Water Cycle & the Carbon Cycle. Highlight or circle cross section from the bottom. Observe the celery under a dissecting photosynthesis & transpiration within your diagrams. microscope. The vascular bundles should be stained red. Sketch what you see. Labe! these structures: epidermis, ground tissue, vascular bundles. (Ref. p. 599-600) 1.) The vascular tissue is composed of which conducts water and which conducts nutrients. 2.) The combination of , and provides enough force to move water through the xylem tissue of even the tallest plant. 3.) When water is abundant, guard cells open stomata and water evaporates. This pulls water up through the . This pressure is known as . When water is scarce, guard cells close stomata which slows down water loss and also slows down (conversion of solar energy to chemical energy). "in Transpiration ■•••k .