Plants produce chemicals called growth regulators such as auxin to regulate tropisms - Leaving Cert Biology - Question 15(a) - 2020
Question 15(a)
Plants produce chemicals called growth regulators such as auxin to regulate tropisms.
(i) What is a tropism?
(ii) Where precisely are auxins produced?
(iii) What ... show full transcript
Worked Solution & Example Answer:Plants produce chemicals called growth regulators such as auxin to regulate tropisms - Leaving Cert Biology - Question 15(a) - 2020
Step 1
What is a tropism?
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A tropism is defined as a growth response of a plant to a stimulus, such as light or gravity. This response can be positive (growth towards the stimulus) or negative (growth away from the stimulus).
Step 2
Where precisely are auxins produced?
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Auxins are primarily produced at the tips of stems and roots, specifically in areas of meristematic tissue. This includes the apical meristem responsible for growth in length.
Step 3
What is the precise benefit to the plant that the shoot is positively phototropic?
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The benefit of positive phototropism in shoots is that it allows the plant to grow towards light, enhancing photosynthesis. This increased light exposure leads to more effective energy production and overall growth.
Step 4
Give two uses in agriculture or horticulture of plant growth regulators.
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Herbicide development for weed control.
Use of rooting powders to enhance root development in cuttings.
Step 5
Compare the effects the different concentrations of IAA have on the growth of the roots and the shoots.
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The graph shows that low concentrations of IAA stimulate root growth, while high concentrations can inhibit it. Conversely, IAA promotes shoot growth at low to moderate concentrations but tends to inhibit it at extremely high levels. This indicates a differential response of roots and shoots to auxin concentrations.
Step 6
State two reasons why the action of an auxin is considered to be similar to the action of a hormone in the human body.
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Auxins can cause a chemical action produced in one area of the plant to act in another area, akin to hormonal signaling in humans.
They can elicit prolonged effects or widespread responses throughout the plant, similar to hormonal effects in the human system.
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