Movement in Plants | Biology for JAMB PDF Download

Introduction

• Definition of plant movements: Plant movements refer to the ability of plants to change their position or orientation in response to various stimuli.
• Importance of plant movements: Plant movements allow plants to optimize their growth, reproduction, and survival by adjusting their position in relation to environmental factors.
• Overview of different stimuli for plant movements: Plants respond to different stimuli such as light, water, touch, and gravity, exhibiting distinct movement patterns.

Phototropism: Response to Light

• Definition of phototropism: Phototropism is the movement of plants in response to light.
• Role of auxin in phototropism: Auxin, a plant hormone, plays a crucial role in phototropism by promoting cell elongation on the shaded side of the plant, causing it to bend towards the light source.
• Positive phototropism: Sunflowers exhibit positive phototropism, as their stems bend towards the direction of the sunlight.
• Negative phototropism: Mushrooms display negative phototropism, growing away from light sources.

Hydrotropism: Response to Water

• Definition of hydrotropism: Hydrotropism is the movement of plants in response to water.
• Role of roots in hydrotropism: Roots play a key role in hydrotropism, sensing water gradients and growing towards water sources.
• Positive hydrotropism: Plant roots exhibit positive hydrotropism, growing towards areas with higher moisture levels to access water.
• Negative hydrotropism: Certain parasitic plants, such as dodder, exhibit negative hydrotropism, avoiding water-rich areas to prevent drowning.

Thigmotropism: Response to Touch

• Definition of thigmotropism: Thigmotropism is the movement of plants in response to touch or mechanical stimuli.
• Role of tendrils in thigmotropism: Tendrils are specialized structures that enable plants to respond to touch and facilitate their climbing or support.
• Positive thigmotropism: Vines, like the pea plant, exhibit positive thigmotropism, where tendrils coil around objects they come into contact with for support.
• Negative thigmotropism: Mimosa pudica, commonly known as the sensitive plant, displays negative thigmotropism, where its leaves fold up in response to touch or disturbance.

Gravitropism: Response to Gravity

• Definition of gravitropism: Gravitropism, also known as geotropism, is the movement of plants in response to gravity.
• Role of auxin in gravitropism: Auxin redistributes within plant cells to influence growth and movement in response to gravity.
• Positive gravitropism: Roots exhibit positive gravitropism, growing towards the force of gravity, allowing them to anchor the plant and absorb nutrients from the soil.
• Negative gravitropism: Stems and shoots exhibit negative gravitropism, growing against the force of gravity to reach sunlight and promote photosynthesis.

Conclusion

• Recap of plant movements in response to light, water, touch, and gravity: Phototropism responds to light, hydrotropism responds to water, thigmotropism responds to touch, and gravitropism responds to gravity.
• Significance of these movements in plant survival and growth: These movements enable plants to optimize their position, acquire essential resources, and respond to environmental cues, ensuring their survival and growth.
• Importance of understanding plant movements in agriculture and horticulture: Knowledge of plant movements helps in optimizing crop growth, designing efficient irrigation systems, and managing plant training and support.