Tropism Lab Report

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Phototropism in growth of lentil plants Introduction: The literal meaning of the word “tropism” is growth in response to a stimulus. But what does this really mean? There are many stimuli that can affect the growth of the plants. For instance, chemicals, water, gravity, temperature, light, etc. The amount, direction, and type of each one of these can play an important role in the growth of the plants. The responsibility of the growth of the plants is with the growth hormones that can be found in the plant. There are five main types of growth hormones. In the recent experiment conducted, phototropism was investigated. The growth response to phototropism is a hormone called auxin. Aim: The aim of this experiment is to investigate the effect of light direction on the growth of lentil plants. This will be done by shining light in four different directions (60° East, 120° West, 90° Top, and light shining from everywhere) for four different groups of plants. (Each plant group with one direction of light) Hypothesis: I predict that all the plants will bend towards their light direction. Meaning, each plant group will bend towards the hole that is made on the box and light is coming from it. I predict this because one of the essential elements in growth of the plants is light and since they cannot survive without it, they have to find a way to get as much light as possible. This is done by a hormone secreted in growth parts of the plants called auxin. This hormone can be very sensible on the tip of the shoot. Then the sun shines on a plant, the auxin made on the shoot moves towards the shady side of the shoot and makes that side grow. As the shady side of the shoot grows, the plant tends to bend towards the sun. This occurs to absorb more sunlight and for photosynthesis to take place. Variables: Independent: The independent variable in this

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