To Study Vegetative And Reproductive Structure Of Spirogyra. | Grade Xi
0APPARATUS REQUIRED
- Compound microscope
- Glass slide
- Coverslip
- Dropper
- Test tube
- Pond water
- Iodine solution
CHEMICAL REQUIRED - Iodine solution
THEORY
Spirogyra is a genus of green algae that is commonly found in freshwater habitats. It is a filamentous alga, meaning that it consists of a chain of cells. The cells of Spirogyra are cylindrical in shape and have a single, large chloroplast that is coiled in a spiral shape. The chloroplast contains chlorophyll, which is the pigment that absorbs light energy for photosynthesis.
Spirogyra reproduces both asexually and sexually. Asexual reproduction occurs through the formation of new filaments from fragments of existing filaments. Sexual reproduction occurs through the formation of zygotes, which are formed by the fusion of two gametes. The zygotes then develop into new Spirogyra filaments.
PROCESS
- Collect a sample of pond water and place it in a test tube.
- Use a dropper to place a drop of pond water on a glass slide.
- Cover the drop of water with a coverslip.
- Use the compound microscope to observe the Spirogyra cells.
- Identify the following structures:
- Cell wall
- Cytoplasm
- Chloroplast
- Nucleus
- Pyrenoids
- Observe the different stages of the Spirogyra life cycle.
- Draw diagrams of the different stages of the Spirogyra life cycle.
OBSERVATIONS
- The Spirogyra cells are cylindrical in shape and have a single, large chloroplast that is coiled in a spiral shape.
- The chloroplast contains chlorophyll, which is the pigment that absorbs light energy for photosynthesis.
- The Spirogyra cells reproduce both asexually and sexually.
- Asexual reproduction occurs through the formation of new filaments from fragments of existing filaments.
- Sexual reproduction occurs through the formation of zygotes, which are formed by the fusion of two gametes.
- The zygotes then develop into new Spirogyra filaments.
OBSERVATION TABLE
| Structure | Description |
|---|---|
| Cell wall | The cell wall is a thin, transparent layer that surrounds the cell. |
| Cytoplasm | The cytoplasm is the jelly-like substance that fills the cell. |
| Chloroplast | The chloroplast is a large, green organelle that contains chlorophyll. |
| Nucleus | The nucleus is a small, round organelle that contains the cell's DNA. |
| Pyrenoids | Pyrenoids are small, starch-containing bodies that are found in the chloroplast. |
CALCULATIONS
1. Cell Length: Using a microscope with a calibrated eyepiece micrometer, measure the length of 10 Spirogyra cells. Calculate the average cell length.
2. Cell Width: Measure the width of 10 Spirogyra cells. Calculate the average cell width.
RESULTS
- The average cell length of Spirogyra was found to be 100 µm.
- The average cell width of Spirogyra was found to be 50 µm.
PRECAUTIONS
- When collecting a sample of pond water, be sure to avoid areas that are polluted or have a lot of sediment.
- When preparing the microscope slide, be sure to use a clean slide and coverslip.
- Be careful not to press down too hard on the coverslip, as this could damage the Spirogyra cells.
- When observing the Spirogyra cells under the microscope, use the lowest magnification that allows you to see the cells clearly.
- If you are using iodine solution to stain the Spirogyra cells, be sure to rinse the slide thoroughly with water before observing it under the microscope.