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.

Can you think of any examples? 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?

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.

Anything Relating to Growth! 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 Tropism Stimulus Response Phototropism Geotropism Chemotropism Thigmotropism Hydrotropism

Important minerals in soil

Review your learning partners work to be sure they have completed the table Tropism Stimulus Response Phototropism Geotropism Chemotropism Thigmotropism Hydrotropism

Task: Draw a Diagram for Each Tropism Example: Hydrotropism Water Growth

Copy and Complete Tropism is how plants respond to their environment. When sunlight is the stimulus this is known as ______tropism. Positive phototropism is where the plant grows _______the light. This happens at the _____tip. ________ phototropism is where the plant grows away from the______, this happens at the_____. When gravity is the stimulus this is known as ______tropism. ________Geotropism is where the plant grows in the direction of_______. This happens at the roots. Negative ___tropism is where the plant grows apposing gravity, this happens at the _____tips. .

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

Tropisms Montage!

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

Auxin Worksheet – To Be Completed By Next Lesson End of Lesson 9

Using Plant Hormones We use plant hormones to control plant growth Collective Memory Task In teams of 4 Reproduce the poster Each person gets 30 seconds to view Report to the next person & instruct them what to draw for 30 seconds. Next person gets 30 seconds to view Lesson 10

Weed killers Selective weed killers kill some plants but not others. This can be useful for getting rid of dandelions in a lawn without killing the grass, or getting rid of thistles in a field without killing the wheat plants. The selective weed killer contains growth hormone that causes the weeds to grow too quickly. The weed killer is absorbed in larger quantities by the weeds than the beneficial plants

Agent Orange

Rooting Powders Powder contains auxins Cuttings are dipped in powder Promotes root growth

Fruit Ripening Ethene – promotes fruit ripening Naturally given off by ripe fruit Converts starch into sugar

How Science Works Design a controlled investigation to find out if apples ripen faster if stored with bananas. For ‘storage’ you could place an unripe apple & a banana into a plastic bag, then seal it. To compare ripeness of apples, you could cut them in half, then stain with iodine solution. The more blue/black colour, the more starch converted into sugar.

How Science Works You must include: The Question you are investigating Do apples ripen faster if...? Hypothesis Your prediction of the results If we store unripe apples .... then... because... Materials Method Results How are you going to measure & record your results

How Science Works D’s will: state, in basic terms, a question, hypothesis, etc.. C’s will: expand on above, using good details B’s will: as above, explaining each section with relevant information A’s will: as above & include detailed descriptions on how results are to be measured.

Plenary Using Plant Hormones Match the sentences Auxiins cause upwards Hormone rooting powder from cell to cell in solution Cuttings can produce clones of the parent plant Hormone weed killers cell growth Shoots grow downwards Flowering can be induced a source of light Lesson 10 Plant hormones can be used to ripen fruit causes roots to grow Roots grow by the use of plant hormones Auxins can diffuse Plants grow towards are not usually harmful to animals

Using Plant Hormones Hormone rooting powder causes roots to grow Auxiins cause cell growth Cuttings can produce clones of the parent plant Hormone weed killers are not usually harmful to animals Shoots grow upwards Flowering can be induced by the use of plant hormones Plant hormones can be used Lesson 10 to ripen fruit Roots grow downwards Auxins can diffuse from cell to cell in solution Plants grow towards a source of light

Homework Complete the questions from p31 of AQA Science Book Your teacher has photocopied these questions. Due: Next Lesson