Bahan Ajar Iritabilitas Pada Tumbuhan Kelas XI (Fase F) Kurikulum Merdeka

Introduction

This tutorial provides a comprehensive overview of irritability in plants, a key concept in biology for high school students in Indonesia. Understanding plant irritability is essential for grasping how plants respond to environmental stimuli, which is crucial for studies in botany and ecology.

Step 1: Understand the Concept of Irritability

• Definition: Irritability in plants refers to their ability to respond to stimuli from their environment. This includes reactions to light, gravity, water, and temperature.
• Importance: Recognizing how and why plants exhibit irritability helps in understanding their survival mechanisms and adaptations.

Step 2: Identify Types of Stimuli

• Light (Phototropism):
  • Plants grow towards light sources, a phenomenon known as phototropism.
  • Example: Sunflowers turning to face the sun.
• Gravity (Gravitropism):
  • Roots grow downward (positive gravitropism), while stems grow upward (negative gravitropism).
• Water (Hydrotropism):
  • Roots can sense moisture levels and grow toward areas with higher water availability.

Step 3: Explore Plant Responses

• Tropisms:
  • Directional growth responses to environmental stimuli.
  • Key types include:
    • Phototropism: Growth towards light.
    • Gravitropism: Growth in response to gravity.
• Nastic Movements:
  • Non-directional responses to stimuli (e.g., the closing of a Venus flytrap).

Step 4: Learn About Hormonal Regulation

• Role of Auxins:
  • Auxins are plant hormones that play a crucial role in regulating growth and response to stimuli.
  • They promote elongation of cells on the side of the plant away from light, causing bending towards the light source.

Step 5: Conduct Experiments

• Practical Application:
  • Set up simple experiments to observe plant responses:
    • Place a plant in a box with one side open to light. Observe how it grows towards the light over several days.
    • Bury a seed in soil and observe root direction in response to gravity.
• Data Recording:
  • Keep a journal to record observations, noting changes in growth patterns and any variations in response.

Conclusion

Understanding irritability in plants is crucial for comprehending how they interact with their environment. By identifying stimuli and observing plant responses, students can gain practical insights into plant biology. For next steps, consider expanding your experiments to include various plant species or environmental conditions to further explore this fascinating topic.