Phototropism and Geotropism

The experiment on phototropism and geotropism focuses on understanding how plants respond to external stimuli, specifically light and gravity, and how these responses impact their growth and orientation. Phototropism investigates how plants bend or grow towards a source of light, emphasising their ability to optimise photosynthesis for energy production. Geotropism, on the other hand, explores how plants respond to gravity by either growing downward (positive geotropism) or upward (negative geotropism), which is crucial for proper root development and nutrient absorption.

This experiment sheds light on the remarkable adaptive mechanisms of plants, demonstrating their capacity to sense and react to their environment, ultimately influencing their overall growth and orientation. 

Here are the steps of the experiment on phototropism and geotropism:

• Take two test tubes and fill them up to about two-thirds of their height with water. Label one as “Test Tube A” and the other as “Test Tube B.”
• Insert one plant into each test tube, ensuring that the roots are submerged in the water, while the stems and leaves extend out of the test tubes. Secure the openings of the test tubes with cotton balls to hold the plants in place.
• Seal the mouth of both test tubes tightly using additional cotton and adhesive tape to prevent any water leakage, even when the test tubes are turned upside down.
• Set up Test Tube A in an upright position using a laboratory stand, and fix Test Tube B upside down in another laboratory stand, ensuring that no water spills out.
• Place the laboratory stands near a window to expose the plants to direct sunlight.
• Over the course of the experiment, which includes days 2, 3, and 4, carefully observe both plants. Record your observations, paying attention to the direction in which the stems and primary roots are growing. Note any features that exhibit positive or negative phototropism and positive or negative geotropism.

In summary, this experiment revealed how plants adapt to their surroundings. We observed how they respond to light and gravity. Stems showed positive phototropism by leaning towards light for better photosynthesis, while roots exhibited positive geotropism by growing downward for stability and nutrient uptake. Stems also displayed negative geotropism, growing away from gravity to find optimal light. Overall, this experiment highlighted plant’s remarkable ability to sense and adapt to their environment, shedding light on their intricate growth mechanisms.

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