Plant Responses to Stimuli

Responses to Internal and External Stimuli

The fight-or-flight response is an organisms primitive, automatic, inborn response that prepares the body to "fight" or "flee" from perceived attack, harm, or threat to its survival. An example would be a gazelle running away from a cheetah that is chasing it. If cornered, the gazelle may face the cheetah in a last-ditch attempt to fight off the predator

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What is the Fight or Flight Response

​All organisms require an exact set of internal conditions to live. Homeostasis (which means equilibrium) allows organisms to function properly. Homeostasis is needed in order to maintain stability when internal or external stimuli push the organism out of balance. Some are external factors such as heat, light, and temperature. Others are internal such as pathogens or lack of water.

Homeostasis

What would be the symptoms and results if a dog ate contaminated food?

The dog may become very ill. In order to rid his body of the germs or parasite, he may vomit, feel sluggish, or have an increase in temperature.

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​What would be the symptoms?

You are shown a potted plant that is leaning over one side of its container. What further examination would be necessary before making an inference about the plants position? The plant must be examined in an effort to determine the source of its response to external stimuli in its growing environment. Lack of turgor pressure could be inferred if the plant is wilted and leaning over the side of the container. A phototrophic response could be inferred if the plant appears healthy and appears to be growing in a specific direction rather than straight up.

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​What do you Infer?

A stimulus is a change in an organisms surroundings or body that causes it to respond. A response is an organisms reaction to a specific stimulus. Examples:You touch something hot (stimulus), so you move your hand away (response).You do not drink enough water (stimulus), so you can become thirsty (response).A plant lacks water and light (stimulus), so it becomes wilted (response). You eat spoiled food (stimulus), so you get sick (response). If in a stressful situation (stimulus), then you will fight for survival or flee for survival (response).If you consume too much liquid (stimulus), then you have to urinate frequently (response).If you are hungry (stimulus), then you eat (response).

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​Influence Stimulus has on Response