Question Video: Recalling What Stimuli Plants Can Respond to with Movement | Nagwa Question Video: Recalling What Stimuli Plants Can Respond to with Movement | Nagwa

Question Video: Recalling What Stimuli Plants Can Respond to with Movement Biology • Third Year of Secondary School

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Which of the following is not a stimulus that plants can respond to with some form of movement? [A] A new light source [B] An increase in soil moisture [C] Gravity [D] Changes in atmospheric pressure

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Video Transcript

Which of the following is not a stimulus that plants can respond to with some form of movement? (A) A new light source, (B) an increase in soil moisture, (C) gravity, or (D) changes in atmospheric pressure.

The directional growth or movement responses of an organism like a plant either toward or away from stimuli are called tropisms. Let’s take a look through the answer options and see if they are stimuli that plants can respond to, starting with option (A), a new light source.

The growth movement of a plant in response to a light stimulus is called phototropism, which we can remember as the prefix photo- means light. For example, if a plant stem receives a light stimulus from only one side, it will grow toward the direction of light. As light is a stimulus that plants can respond to with movement, option (A) is incorrect.

Option (B) suggests that an increase in soil moisture will stimulate the movement of a plant. The roots of many plants tend to grow toward water, or moisture, in soil through a process called hydrotropism. We can remember this name as the prefix hydro- means water. As water is a stimulus that plants can grow toward, option (B) is also incorrect.

Option (C) suggests that plants can move in response to gravity. Geotropism, or gravitropism, describes the movement of a plant in response to gravity, which is often observed in the downward growth of plant roots. So this option can also be eliminated.

Option (D) suggests that plants might be able to move in response to changes in atmospheric pressure. Plants don’t require a specific atmospheric pressure to grow, and a change in atmospheric pressure won’t affect the movement of plants.

As we are looking for an answer that is not a stimulus plants can respond to, this means that we have found the correct answer. The answer choice that is not a stimulus that plants can respond to with some form of movement is (D), changes in atmospheric pressure.

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