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Title: Turgor Pressure in Plants Write in your journal Title on one side Lab here: pre-title now (will glue in after graded) Watch the video: https://www.youtube.com/watch?v=fhsurzE_-J0 In your journal- answer below: 1. What happened to the celery when water was added? 2. Why? Be as specific as you can. Recall what you know about plant cells, cell walls/membranes and the purpose of vacuoles. All systems, including ecosystems and the human body, need a way of maintaining equilibrium, or balance. When a system is in equilibrium, it is stable, and all its parts function smoothly. All organisms, whether they are humans, bacteria, or plants, must maintain internal equilibrium no matter what happens in their environment. The process by which the body’s internal environment is kept stable in spite of changes in the external environment is called homeostasis. Equilibrium Like all organisms, plants need to maintain water equilibrium in spite of changing conditions. Many plants obtain water through their roots (and the cells in those roots). The cells in a plant’s roots, like all cells, are bound by a thin, flexible structure called the cell membrane. Equilibrium in Plants Osmosis Water enters through the cell membrane. Moving from an area of high concentration to low concentration. The structure of plant cells contributes to a plant’s ability to maintain water balance. The cell wall is rigid, located outside the cell membrane Since cell walls are rigid, they limit the ability of plant cells to expand. As water molecules move into a plant cell, the expanding cell membrane presses against the rigid cell wall. The pressure of water against the cell wall of a plant cell is called turgor pressure. Animation of Turgor Pressure in a cell What is Turgor Pressure? Turgor pressure helps give shape and firmness to plant stems and leaves. If the environment outside a plant cell is dry, more water leaves the plant cell than enters it. As a result, turgor pressure inside cells is reduced. The cell membranes no longer press against the cell walls. The plant then loses its stiffness and wilts. Turgor Pressure Read Instructions What would be a good hypothesis? Turgor Pressure Lab Each section has procedures. Read them carefully. Do not begin work if you do not understand them – ask for help! At each station all of the supplies are labelled, make sure you are using the correct solution! Demonstration of procedure: Procedure: Place a thin sliver of moist onion tissue (red colored) onto a glass slide. Put a drop of water on the slide and drop a cover slip. Record your observations. Now touch the edge of the slide with a dropper filled with salt solution. Allow salty water to draw across the cover slip. Record the time and record your observations. Lab Completion Lab MUST be clean before you are allowed to sit down Once you are approved to go back to your seat, finish drawings by adding color Lab is not complete until the conclusion questions are answered. If not done in class, they are homework and due next class. No salt vs. high salt