Tropism


 * TROPISM **
 * LISTENING EXERCISE 5**
 * PASSAGE ONE**
 * Page 164**
 * Today I'll be talking about the concept of tropism as it relates to plants. Tropism,**
 * for those of you who don't know, refers to a bending of a plant or a part of a plant in response to an outside stimulus.**
 * There are three important kinds of tropism. They are phototropism, geotropism, and hydrotropism. In each of these kinds of tropism, a plant, or a part of a plant, bends in response to a different kind of outside stimulus.**
 * First, we'll discuss phototropism. The outside stimulus in phototropism is light. When a plant is affected by phototropism, it grows in the direction of a light source such as the Sun.**
 * The second kind of tropism is geotropism. In geotropism, the outside stimulus is gravity. In a plant affected by geotropism, the affected part of the plant grows directly downward because of the pull**
 * of gravity. When a plant's affected by geotropism, it's often the root structure**
 * that's affected.**
 * OK. The final kind of tropism I1l discuss today is hydrotropism. When hydrotropism affects a plant, this means that the plant is drawn toward water. A plant under the effect of hydrotropism will grow in the direction of its water source.**
 * 1. HOW IS THE INFORMATION IN THE PASSAGE ORGANIZED?**
 * 2. WHICH OF THESE KINDS OF TROPISM ARE**
 * DESCRIBED IN THE PASSAGE?**
 * 3. DRAG THE APPROPRIATE DESCRIPTION OF EACH TYPE OF TROPISM TO THE BOX BELOW THE NAME OF THE TYPE OF TROPISM.**

The concept of tropism relates to plants. Tropism, refers to a bending of a plant or a part of a plant in response to an outside stimulus.

There are three important kinds of tropism. They are phototropism, geotropism, and hydrotropism. In each of these kinds of tropism, a plant, or a part of a plant, bends in response to a different kind of outside stimulus.

First, we'll discuss phototropism. The outside stimulus in phototropism is light. When a plant is affected by phototropism, it grows in the direction of a light source such as the Sun.

The second kind of tropism is geotropism. In geotropism, the outside stimulus is gravity. In a plant affected by geotropism, the affected part of the plant grows directly downward because of the pull of gravity. When a plant's affected by geotropism, it's often the root structure that's affected.

The final kind of tropism hydrotropism. When hydrotropism affects a plant, this means that the plant is drawn toward water. A plant under the effect of hydrotropism will grow in the direction of its water source.

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