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Growth Control in Plants. Learning Objectives. Explain how plant growth is controlled by hormones. Describe how these hormones can be used to change plant growth. Numbered Heads Together Revision Number based on shoe size Smallest Shoe = Person 1 Biggest Show = Person 4
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Learning Objectives • Explain how plant growth is controlled by hormones. • Describe how these hormones can be used to change plant growth.
Numbered Heads Together Revision • Number based on shoe size • Smallest Shoe = Person 1 • Biggest Show = Person 4 • Write down your ideas to answer the question • Stand up when you are ready to share with your group • As a group decide on 1 answer for the whole group • Sit down when ready • Random number to be called on to answer. • SO EVERYONE MUST BE READY TO ANSWER! What is a Hormone? What do hormones do? Can you think of any examples?
Chemical Messengers Coordinate systems Oestrogen What is a Hormone? What do hormones do? Insulin Glucagon Testosterone Can you think of any examples? ADH HGH Causes a change in how the body works Travel in the blood, secreted by glands Control Growth, blood sugar, sex development, mood, metabolism.
Hormones in Plants What do hormones control in plants? Anything Relating to Growth! Roots and Shoots Seed Germination Leaf Fall Disease Resistance Fruit Formation and Ripening Flowering Time Bud formation
Sensitivity – Responding to the environment • Plants respond to stimuli to: • Avoid stress • Avoid being eaten • Enhance survival • Improve chances of having offspring • The way a plant grows is controlled by the hormones • These are sensitive to the environment & can make • adjustments to help plant survive
Tropisms • “Directional growth response” • Plants grow in a certain direction in response to a stimulus Let’s Explore Tropisms!
Use your observations from the following to complete the table
Review your learning partners work to be sure they have completed the table
Task: Draw a Diagram for Each Tropism Example: Hydrotropism Growth Water
What Causes Tropisms? • Hormone Auxin • Auxin promotes growth
What Causes Tropisms? • Shoots of plants contain Auxin A) When light shines directly above tip, growth is equal towards light source
What Causes Tropisms? B)When light shines from an angle: • Sunlight breaks down Auxin • So the side of the tip that has the most direct sunlight will have the least amount of Auxin • Area of the plant that is more shaded will have more Auxin • More growth on shaded side • Lop sided growth & plant bends towards light
Match the correct scenario to the tropism. Roots Growing Downwards into Dark Soil Positive Phototropism Negative Geotropism Roots Growing Upwards towards light. Shoots Growing Upwards Negative Phototropism Roots Growing Downwards. Positive Geotropism
For your revision, make sure that you are comfortable with each of the following areas of knowledge.