Gaining Water and Nutrients PDF

Gaining water and nutrients Section Objectives 1. Define diffusion and osmosis (passive transport). 2. Describe the process of diffusion. 3. Explain the process of osmosis with examples of plant cells. 4. Differentiate betw...

Gaining water and nutrients Section Objectives 1. Define diffusion and osmosis (passive transport). 2. Describe the process of diffusion. 3. Explain the process of osmosis with examples of plant cells. 4. Differentiate between diffusion and osmosis. 5. Revise differences in plant and animal cells learnt in the previous grade. 6. Give brief explanation on concentrations of solutions. 7. Explain osmosis using plant cells and animal cells. 8. Explain the process of osmosis with more examples of animal cells like red blood cells. 9. Elaborate the process of osmosis with more examples of few experiments. 10. Give brief idea of stomata and transpiration and active transport. Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. It is a passive process. In a cell, water always moves to reach an equal concentration on both sides of the membrane. Osmosis: The movement of water molecules from higher concentration to lower in presence of partially permeable membrane.( eg. cell membrane ) What controls osmosis? Unequal distribution of Before After particles, called Osmosis Osmosis a concentration gradient, is one factor that controls osmosis. Selectively Water molecule permeable Sugar molecule membrane  Osmosis: Diffusion of Water Most cells whether in multicellular or unicellular organisms, are subject to osmosis because they are surrounded by water solutions. Animal cell in an isotonic solution isotonic solution- (= concentrations) the concentration of H2O dissolved substances H2O in the solution is the same as the concentration of dissolved substances inside the cell. Water Molecule Dissolved Molecule Animal cell in an isotonic solution water molecules move into and out of the cell H2O at the same rate, and H2O cells retain their normal shape. Water Molecule Dissolved Molecule Cells in an isotonic solution A plant cell has its normal shape and pressure in an isotonic solution. Animal cell in a hypotonic solution hypotonic solution: dilute solution thus low solute concentration H2O In a hypotonic H2O solution, water enters a cell by osmosis, causing the cell to swell. Water Molecule Dissolved Molecule Cells in a hypotonic solution Plant cells swell beyond their normal size as pressure increases. (plants prefer this –it makes the leaves firm) Animal Cell in a hypertonic solution hypertonic solution: concentrated solution, thus a high solute concentration H2O In a hypertonic solution, H2O water leaves a cell by osmosis, causing the cell to shrink Water Molecule Dissolved Molecule Plant Cells in a hypertonic solution Plant cells lose pressure as the plasma membrane shrinks away from the cell wall. PLASMOLYSIS Passive transport Active transport  Active Transport Active transport :Movement of materials through low concentration to high concentration against the concentration gradient and requires energy from the cell. Cellular energy Minerals like nitrates, phosphates, potassium and magnesium are absorbed into root hair cells using active transport. Cellular energy During transpiration water evaporates through the stomata present on the surface of the leaves. Transpiration is mainly responsible for the loss of water that was absorbed by the plants. However, it is important for plants as it helps in the movement of water to the top of tall trees. As a result, it helps in the distribution of water throughout the plant. It also helps in the cooling of the plant. Rate of transpiration depends on temperature, relative humidity, air, surface area, and sunlight intensity. Uses of water in plants: 1. Structural support. 2. Photosynthesis. 3. Maintains body temperature (coolant). 4. Solvent.