Plant Hormones - Auxins
This lesson covers:
- What auxins do to shoots and roots
- How positive and negative phototropism work
- How positive and negative geotropism work
Which stimuli can plants detect?
(Select all that apply)
Sound
Light
Gravity
Touch
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Do plants have a nervous system?
Yes
No
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True or false? Plant hormones only act locally.
True
False
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_________ are a family of plant hormones produced in the tips of shoots and roots. Once produced, they diffuse backwards along the shoot or root.
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Which two of the terms below mean the same thing?
Geotropism
Gravitropism
Ectotropism
Phototropism
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Auxins always accumulate on the: Lower side Upper side
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Shaded side Sunny side
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Shoots are considered:
(Select all that apply)
Positively phototropic
Negatively phototropic
Positively geotropic
Negatively geotropic
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Which statement about plant roots is correct?
They are negatively phototropic and negatively gravitropic
They are negatively phototropic but positively gravitropic
They are positively phototropic but negatively gravitropic
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State which direction the plant shoot in the image above will grow, and explain why.
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What is a phototropism?
A response to temperature
A response to light
A response to gravity
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Where are auxins made in the plant?
In the older part of a stem or root
In the growing tip of a stem or root
All plant cells can make auxins
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What happens to make a root grow in the direction of the force of gravity?
The bottom side grows more than the top side
The top side grows more than the bottom side
The top and bottom sides grow at the same rate
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What is positive phototropism?
Plants grow down towards the ground
Plants grow away from the light source
Plants grow towards the light source
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What effects do auxins have on plants?
Shoot cell inhibition and root cell growth
Shoot cell growth and root cell growth
Shoot cell growth and root cell inhibition
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Tip for remembering which side of the shoot or root auxins accumulate on:
- Light breaks down auxin, so there will be more auxin on the shaded side.
- Gravity pulls auxins downwards, so there will be more auxin on the lower side.