Use your knowledge of indoleacetic acid (IAA) to explain the growth curvature shown in Figure 1 - AQA - A-Level Biology - Question 3 - 2021 - Paper 1
Question 3
Use your knowledge of indoleacetic acid (IAA) to explain the growth curvature shown in Figure 1.
Figure 1 shows an investigation into growth factors in plants.
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Worked Solution & Example Answer:Use your knowledge of indoleacetic acid (IAA) to explain the growth curvature shown in Figure 1 - AQA - A-Level Biology - Question 3 - 2021 - Paper 1
Step 1
Tip produces IAA
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Answer
The tip of the plant shoot produces indoleacetic acid (IAA), a key plant hormone that regulates growth.
Step 2
IAA diffuses into shoot
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Answer
When the tip is removed, the IAA production is also halted on that side of the shoot. However, when the tip is replaced, IAA can still diffuse into the shoot.
Step 3
Elongation of cells on one side
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Answer
The curvature seen in Figure 1 occurs due to the unequal distribution of IAA. With the tip only applied to one side, IAA promotes greater elongation of cells on that side compared to the other, causing the shoot to bend towards the side with lesser IAA concentration.
