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. - PowerPoint PPT PresentationTRANSCRIPT
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.• Do not use adrenaline as an exampleHormone Gland Action
hormones
Produced by the adrenal glands (above the kidneys) Prepares the body for action:
Adrenaline Effect on musclesAdrenal glands Fight or flight
Action Reason
Increases blood glucose level
for muscles to use to produce ATP energy for contraction
Increases heart rate to transport more glucose and oxygen to the muscle cells
Dilates airways so more air reaches alveoli for increased gas exchange
Dilates blood vessels in brain and muscles
to deliver more glucose and oxygen to these cells
Constricts blood vessels in gut and other organs
allowing blood to be diverted to muscles
B7: COORDINATION AND RESPONSE
7.2 Tropic responses
What is a tropism? Plants grow towards or away from stimuli The growth response is called a tropism
gravity
light
Shoots will grow towards light – a positive tropism
Shoots will grow against gravity – a negative tropism
The stimuli Phototropism is the growth response
towards or away from light Geotropism is the growth response with or
against gravity
geotropism
phototropism
Putting it all together: Complete this table:
Response Tropism
Shoots growing towards sunlight Positive phototropism
Shoots growing against gravity Negative geotropism
Roots growing away from sunlight Negative phototropism
Roots growing with gravity Positive geotropism
How do plants grow to the 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
light
How do plants grow to the light?
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
Auxin at work
Phototropism experiment
How do plants respond to gravity?
gravity
shoots grow up
roots grow down
negative geotropism
positive geotropism
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 downPhototropism and ge
otropism
Textbook Questions Complete the following summary
questions:P153 exercise 1P155 exercises 1, 2 and 3
Complete the following exam-style questions:P156 question 4