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What is an auxin? State a site of auxin secretion - Leaving Cert Biology - Question b - 2004
Question b
What is an auxin? State a site of auxin secretion. How may the action of an auxin be considered similar to the action of a hormone in the human body? Define tropism... show full transcript
Worked Solution & Example Answer:What is an auxin? State a site of auxin secretion - Leaving Cert Biology - Question b - 2004
Step 1
What is an auxin? State a site of auxin secretion. How may the action of an auxin be considered similar to the action of a hormone in the human body?
Answer
An auxin is a plant hormone that acts as a growth regulator, promoting elongation and other growth processes in plants. A major site of auxin secretion is the tip of the shoot or buds, as well as developing leaves or seeds.
The action of auxins can be likened to that of hormones in the human body in several ways. Firstly, like hormones, auxins are synthesized in one location and transported to other parts of the plant where they induce a response. Secondly, their effects can be slow-acting and often lead to long-lasting changes in growth patterns.
Step 2
Define tropism. List three types of tropism.
Answer
Tropism refers to the growth response of a plant to an environmental stimulus. This can involve bending or moving towards or away from the stimulus.
Three types of tropism include:
- Phototropism (response to light)
- Gravitropism (response to gravity)
- Hydrotropism (response to moisture)
Step 3
Relate the role of an auxin to one of the tropisms that you have listed in (ii).
Answer
Auxins play a crucial role in phototropism. They are distributed unevenly in response to light, leading to differential growth in the plant. When light shines more on one side, auxins accumulate on the darker side, causing those cells to elongate more. This results in the plant bending towards the light, promoting optimal light absorption for photosynthesis.