Tropic movements are directional movement.the directional movement of plant in response to an external stimulus in which the direction of stimulus determined the direction of response is called tropic movement .ExAmple: the bending of stems of plants towards the sunlight

**Tropic Movements - An Overview**

Tropic movements refer to the directional responses of plants to external stimuli such as light, gravity, and touch. These movements are often seen in plants and are crucial for their survival and growth. The movements are typically slow and occur over a longer period of time compared to nastic movements, which are rapid and reversible.

**Explanation of the Correct Answer**

The correct answer to the question is option 'C', which states that tropic movements are uni-directional. This means that the movements of plants in response to external stimuli occur in a specific direction.

**In Response to Light**

Plants exhibit tropic movements in response to light through a phenomenon called phototropism. Phototropism is the movement of plants towards or away from a light source. The movement is typically towards the light, known as positive phototropism. This response is crucial for plants to maximize their exposure to sunlight, which is essential for photosynthesis.

**In Response to Gravity**

Tropic movements also occur in response to gravity. This is known as gravitropism or geotropism. In gravitropism, plants respond by growing either towards gravity (positive gravitropism) or against gravity (negative gravitropism). For example, roots exhibit positive gravitropism by growing towards the gravitational pull while shoots exhibit negative gravitropism by growing against gravity, towards the light.

**Uni-Directionality of Tropic Movements**

Tropic movements are uni-directional, meaning they occur in a specific direction. The direction of movement is determined by the stimulus to which the plant is responding. In the case of phototropism, the movement is towards light, while in gravitropism, it is either towards or against gravity.

**Non-Directional Movements**

Non-directional movements, on the other hand, refer to movements that occur in multiple directions or without a specific orientation. These movements are not considered tropic movements. Examples of non-directional movements include nastic movements, which are rapid and reversible movements in response to stimuli such as touch, temperature, or moisture. These movements are typically observed in plant parts like leaves and petals.

**Conclusion**

In conclusion, tropic movements in plants are uni-directional responses to external stimuli such as light and gravity. Phototropism and gravitropism are two examples of tropic movements that allow plants to adapt and optimize their growth in relation to their environment. Non-directional movements, on the other hand, refer to movements that occur without a specific orientation and are not considered tropic movements.