UNIT OVERVIEW

Plants cannot walk away from danger or move towards food. Instead, they use chemical messengers called hormones to control how they grow, develop, and defend themselves.

In this unit, you will learn how two important plant hormones—auxins and gibberellins—control plant growth. You will also discover how plants make special chemicals to protect themselves from diseases and animals that want to eat them.

What you need to know already:

• Grade 10: Basic plant structure and tissues
• Grade 11: Photosynthesis and how plants get nutrients
• Term 2, Lesson 2: How hormones work and negative feedback

What you will learn:

1. How auxins control growth in stems and roots, fruit formation, leaf fall, and bending towards light or gravity
2. How gibberellins make stems grow longer
3. How plants use defence chemicals to protect themselves
4. How to design and carry out experiments on plant responses to light and gravity

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