Where would the highest concentrations of auxins be found?
a)closest to the roots
b)in the lateral buds
c)near the apical meristem
d)on the sunny side of a stem
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| Answer: c |
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How do auxins influence cell elongation?
a)They cause cell membranes to thicken and become rigid.
b)They lower the tensile strength of the cell membrane.
c)They trigger the end to cell division and cell differentiation.
d)They weaken bonds of cellulose molecules in the cell wall.
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| Answer: b |
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Under low light intensity internodes of a plant will lengthen. Which plant hormone is the cause of this plant response?
a)abscisic acid
b)auxins
c)cytokinins
d)gibberellins
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| Answer: d |
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While auxins inhibit the growth of lateral shoots, what plant hormone promotes the growth of lateral shoots?
a)abscisic acid
b)cytokinins
c)ethylene
d)gibberellins
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| Answer: b |
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Seeds will lie dormant until conditions are optimal for seed germination. Which plant hormone promotes seed dormancy?
a)abscisic acid
b)auxins
c)cytokinins
d)gibberellins
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| Answer: a |
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Deciduous trees will lose their leaves in the fall. Which plant hormone promotes leaf abscission?
a)abscisic acid
b)cytokinins
c)ethylene
d)gibberellins
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| Answer: c |
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How are synthetic auxins, such as indolebutyric acid (IBA), used in the horticulture industry?
a)to kill weeds in landscapes and greenhouses
b)to promote rooting during vegetative propagation
c)to reduce plant height and promote compact growth
d)to stimulate flowering in some plants
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| Answer: b |
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How does phototropism occur?
a)Auxins move across and accumulate on the shady side of a plant stem causing the cells to elongate more than the cells on the bright side of the stem.
b)Auxins are produced in cells on the shady side of the stem in response to phototropin and cause cell elongation to occur.
c)Cytokinins produced in the roots cause cells on the shady side of a stem to divide more rapidly than the cells on the bright side of the stem.
d)Gibberellins migrate to the shady side of the stem, and the increased concentration causes the cells to elongate more than the cells on the bright side of the stem.
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| Answer: a |
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How is the downward growth of roots explained?
a)Amyloplasts settle on the lower side of statocytes because of gravity.
b)Auxins promote cell elongation that pushes the roots through the soil.
c)Cytokinins work in opposition to auxins to direct growth downward.
d)Phototropin detects gravity and controls the plants’ developmental sequence.
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| Answer: a |
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The tendril of a grapevine that wraps around an object is an example of _____.
a)positive aerotropism
b)negative thigmotropism
c)positive thigmotropism
d)positive traumatropism
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| Answer: c |
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