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)
Touch
Light
Sound
Gravity
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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
Ectotropism
Gravitropism
Phototropism
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Auxins always accumulate on the: Upper side Lower side
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Sunny side Shaded 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 but positively gravitropic
They are positively phototropic but negatively gravitropic
They are negatively phototropic and 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?
All plant cells can make auxins
In the growing tip of a stem or root
In the older part of a stem or root
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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 and bottom sides grow at the same rate
The top side grows more than the bottom side
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What is positive phototropism?
Plants grow towards the light source
Plants grow away from the light source
Plants grow down towards the ground
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What effects do auxins have on plants?
Shoot cell inhibition and root cell growth
Shoot cell growth and root cell inhibition
Shoot cell growth and root cell growth
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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.