What is the difference between Nastic movements and Tropic movements?

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Answer

Answer

Both tropic and nastic movements are influenced by environmental cues.
Tropic movements are found virtually in all plants but nastic movements are mostly found in specialized plants and organs.
In tropic movements, there is directional growth of a plant, or part of a plant, in response to an external stimulus such as gravity or light. So the direction of the stimulus controls the orientation of growth. The direction of a nastic movement is independent of where the signal comes from. It is only the quality, and not the direction, of the stimulus that triggers a response.
In tropism, the effect is more or less permanent. Most nastic movements are temporary and reversible.
Nastic movements are more specialized in function and distribution than tropic movements.

Answer

Nastic Movements

Nastic movements, also known as nastic responses, are non-directional responses of plants to external stimuli. These movements are not dependent on the direction of the stimulus but are rather determined by the intensity of the stimulus. Nastic movements occur at a relatively slow rate and are reversible. They are mainly observed in response to environmental factors such as temperature, humidity, light, and touch.

Types of Nastic Movements

There are several types of nastic movements exhibited by plants:

1. Nyctinasty: This is the rhythmic opening and closing of flowers or leaves in response to the day-night cycle. Examples include the closing of flowers at dusk or the folding of leaves during the night.

2. Thigmonasty: Thigmonastic movements are triggered by touch or contact. The response can be observed in plants such as the sensitive plant (Mimosa pudica), which folds its leaflets when touched.

3. Seismonasty: Seismonastic movements occur in response to mechanical stimuli, such as wind or vibration. Examples include the folding of Venus flytrap leaves upon capturing prey or the closing of leaves in response to strong winds.

4. Thermonasty: These movements are in response to changes in temperature. For instance, certain flowers open or close depending on the temperature, ensuring optimal conditions for pollination.

Tropic Movements

Tropic movements, also known as tropisms, are directional responses of plants to external stimuli. Unlike nastic movements, tropic movements are dependent on the direction of the stimulus. These movements occur at a relatively slow rate and are irreversible. Tropisms are mainly observed in response to factors such as light, gravity, moisture, and chemicals.

Types of Tropic Movements

There are several types of tropic movements exhibited by plants:

1. Phototropism: Phototropism is the growth or movement of plants towards or away from a light source. This allows plants to optimize photosynthesis by maximizing light exposure.

2. Geotropism: Geotropism, also known as gravitropism, is the growth or movement of plants in response to gravity. Roots exhibit positive geotropism, growing towards gravity, while shoots exhibit negative geotropism, growing against gravity.

3. Hydrotropism: Hydrotropism is the growth or movement of plants towards or away from moisture or water. It helps plants to locate water sources for survival.

4. Chemotropism: Chemotropism is the growth or movement of plants towards or away from specific chemicals. It enables plants to find nutrients or avoid toxic substances.

Conclusion

In summary, nastic movements are non-directional and reversible responses of plants to external stimuli, while tropic movements are directional and irreversible responses. Nastic movements are determined by the intensity of the stimulus, while tropic movements are dependent on the direction of the stimulus. Understanding these different types of movements helps us comprehend how plants adapt and respond to their environment.

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