(a) What is an auxin?
An auxin is a plant growth regulator that can function as either a promoter or an inhibitor of growth - Leaving Cert Biology - Question 5 - 2018
Question 5
(a) What is an auxin?
An auxin is a plant growth regulator that can function as either a promoter or an inhibitor of growth.
(b) With regard to auxins, state:
(i)... show full transcript
Worked Solution & Example Answer:(a) What is an auxin?
An auxin is a plant growth regulator that can function as either a promoter or an inhibitor of growth - Leaving Cert Biology - Question 5 - 2018
Step 1
What is an auxin?
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Answer
An auxin is a plant growth regulator that can function as either a promoter or an inhibitor of growth.
Step 2
A precise location in plants where they are produced.
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Answer
Auxins are primarily produced in the shoot tips or root tips, in meristematic tissues, seeds, or young leaves.
Step 3
One example of an inhibitory function.
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Answer
Auxins are involved in apical dominance, where they slow growth in side branches, hence preventing lateral development.
Step 4
Exactly how does an unequal concentration of auxin in the elongation zone affect the growth of either a shoot or a root?
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Shoot. An unequal concentration of auxin in the shoot results in a higher auxin concentration leading to an increased rate of cell division and more growth on that side.
OR
Root. An unequal concentration of auxin in the root results in a lower rate of cell division on the side with higher auxin concentration, restricting growth in that area.
Step 5
Suggest what could cause an unequal concentration of auxin in a shoot or in a root?
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Shoot. A difference in light direction (phototropism) or gravity can lead to unequal auxin distribution in the shoot.
OR
Root. The root may experience unequal auxin concentrations due to gravity or variations in water concentration.
Step 6
State two uses in horticulture of auxins or related compounds.
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Answer
Promote ripening in fruit.
Used in rooting powder for plant propagation.
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