Question Video: Defining the Process by Which Plant Roots Grow in Response to Water | Nagwa Question Video: Defining the Process by Which Plant Roots Grow in Response to Water | Nagwa

Question Video: Defining the Process by Which Plant Roots Grow in Response to Water Biology • Second Year of Secondary School

Complete the following statement: The response of plant roots to grow in the direction of a water source is known as _.

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Video Transcript

Complete the following statement. The response of plant roots to grow in the direction of a water source is known as blank.

You might think of plants as immobile organisms, but amazingly plants can move and grow in response to the world around them, sometimes surprisingly quickly. Think of a house plant growing toward a window or even a plant growing vertically out of the soil. The directional growth responses of an organism toward or away from stimuli are called tropisms. While a negative tropism is growth away from a stimulus, a positive tropism is growth toward a stimulus. There are lots of potential tropisms in plants. Let’s take a look at a couple of them.

Phototropism describes plant growth in response to a light stimulus. Phototropism is very useful to plants as they require light for photosynthesis to make their own food. Therefore, many plant shoots and leaves are usually observed to grow toward a light source, like the Sun shining through the window in our house plant example. However, we are looking for the response of plant roots, not shoots, and in response to water and not light. Let’s take a closer look at this plant’s roots so we can see what the correct tropic response might be.

Hydrotropism describes directional plant growth in response to water or moisture. Plant roots often grow toward water sources underground as they need to extract water from the soil, partly because water is a key reactant in photosynthesis. The growth of plant roots toward water and soil is an example of positive hydrotropism.

Now that we have discussed what tropisms are and a couple of examples of different tropisms, we can answer our question. The response of plant roots to grow in the direction of a water source is called hydrotropism.

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