This activity contains 10 questions.
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Which of the following seedlings will probably bend toward the light?
one whose tip is separated from its base by a gelatin block
one whose tip is covered with a black plastic cap
one whose tip is separated from its base by aluminum foil
one whose tip is cut off
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Plant hormones act by affecting the activities of _____.
genes, membranes, and enzymes
enzymes
genes
membranes
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Which of the following plant hormones inhibit(s) growth?
gibberellins
abscisic acid
cytokinins
auxin
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Plant hormones _____.
are not produced by plants
include one that is a gas
usually function in the location at which they are synthesized
are active only in large amounts
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Thigmotropism is a movement in response to _____.
chemicals
light
gravity
touch
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A biological cycle with a period of about 24 hours is called _____.
a photoperiod
thigmotropism
abscission
a circadian rhythm
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The pigments involved in the flowering process (and other developmental events in plants) are _____.
rhodopsins
chlorophylls
phytochromes
beta-carotenes
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The Pr form of the phytochrome pigment has maximum absorption in the _____ part of the spectrum.
red
far-red
blue and red
blue
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Most plants produce flowers when _____.
the days are the right length
the nights are the right length
the soil reaches a certain temperature
a certain number of days have passed since they last flowered
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What is systemic acquired resistance?
When an insect incorporates plant-produced canavanine instead of arginine, the insect dies.

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It is the coiling of a plant around a rigid object.
It is the matching of the products of a plant"s R gene with the products of a pathogen"s Avr gene.

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When an infection occurs at one site on a plant, hormones trigger a signal transduction pathway that leads to increased production of defensive chemicals by other parts of the plant.
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