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B7: Coordination and Response

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B7: Coordination and Response. 7.1 Hormones. What is a hormone?. A chemical substance Produced in an endocrine gland Carried in the blood Alters the activity of the target organ(s) Destroyed by the liver Copy and complete this table using p152 fig12.6.1.

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B7: Coordination and Response

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  1. B7: Coordination and Response 7.1 Hormones

  2. What is a hormone? • A chemical substance • Produced in an endocrine gland • Carried in the blood • Alters the activity of the target organ(s) • Destroyed by the liver • Copy and complete this table using p152 fig12.6.1. • Do not use adrenaline as an example hormones

  3. Effect on muscles Adrenaline Adrenal glands Fight or flight • Produced by the adrenal glands (above the kidneys) • Prepares the body for action:

  4. B7: Coordination and Response 7.2 Tropic responses

  5. What is a tropism? • Plants grow towards or away from stimuli • The growth response is called a tropism Shoots will grow towards light – a positive tropism light Shoots will grow against gravity – a negative tropism gravity

  6. The stimuli • Phototropism is the growth response towards or away from light • Geotropism is the growth response with or against gravity phototropism geotropism

  7. Putting it all together: • Complete this table:

  8. How do plants grow to the light? light • A hormone called auxin is made in the tip of the shoot • Auxin causes shoot cells to enlarge • When light is directly overhead, auxin diffuses equally down the shoot • The shoot grows straight up

  9. How do plants grow to the light? Auxin at work • When light is directional, the auxin moves to the shaded side of the shoot • The cells on the shaded side elongate more than the cells on the lighted side • The shoot grows towards the light light

  10. Phototropism experiment

  11. How do plants respond to gravity? shoots grow up negativegeotropism roots grow down gravity positivegeotropism

  12. How do plants respond to gravity? • Auxin is made in the shoot and root tips • Auxin causes slowed growth in root cells • When a plant is laid on its side, auxin collects in the lower cells • The lower cells in the shoot elongate and the shoot grows upwards • The lower cells in the root slow in growth and the roots grow down Phototropism and geotropism

  13. Textbook Questions • Complete the following summary questions: • P153 exercise 1 • P155 exercises 1, 2 and 3 • Complete the following exam-style questions: • P156 question 4

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