Explanation:

Plants have the ability to move and respond to different stimuli in their environment. Auxin is a plant hormone that plays a crucial role in regulating plant growth and development, including movements in response to different stimuli. However, not all plant movements are directly related to changes in auxin levels.

Nyctinastic Leaf Movements:

- Nyctinasty is the movement of leaves in response to changes in light and darkness.
- During the day, the leaves are open and spread out to maximize photosynthesis.
- At night or when exposed to darkness, the leaves close up and droop down to protect the plant from potential damage or water loss.
- This movement is not directly related to changes in auxin levels. Instead, it is primarily controlled by changes in turgor pressure within the cells of the leaf.

Other Movements in Plants:

- Movement of roots towards soil: This movement is known as positive geotropism or gravitropism. It involves the growth of plant roots in response to gravity, with the roots growing downward towards the soil. Auxin plays a crucial role in regulating this movement, as it accumulates on the lower side of the root and stimulates cell elongation.

- Movement of sunflower tracking the direction of sun: This movement is known as phototropism. It involves the growth of plant shoots in response to light, with the shoots bending towards the light source. Auxin also plays a crucial role in regulating this movement, as it accumulates on the shaded side of the shoot and stimulates cell elongation.

- Movement of shoot towards light: This movement is also known as phototropism, and as mentioned above, it is directly related to changes in auxin levels.

In summary, while auxin plays a crucial role in regulating many plant movements, not all movements are directly related to changes in auxin levels. Nyctinastic leaf movements, for example, are primarily controlled by changes in turgor pressure within cells, rather than changes in auxin levels.

Nyctinastic leaf ,in movement of roots towards soil is +ve geotropism and movement of shoot and sunflower towards sunlight is + be phototropism which is becz of auxin while in Nyctinastic leaf movement us due to change in level of water as seen in plant mimosa pudica in which the pulvinous losses water and the leaf curl up due to touching that why it is also known as touching me not plant..