Name the group of substances in plants which control responses to external stimuli - Leaving Cert Biology - Question b(c) - 2011
Question b(c)
Name the group of substances in plants which control responses to external stimuli.
What is a hormone?
State two ways in which hormones are similar to the group of s... show full transcript
Worked Solution & Example Answer:Name the group of substances in plants which control responses to external stimuli - Leaving Cert Biology - Question b(c) - 2011
Step 1
Name the group of substances in plants which control responses to external stimuli.
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Answer
The group of substances in plants that control responses to external stimuli is known as plant growth regulators, commonly referred to as auxins.
Step 2
What is a hormone?
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Answer
A hormone is a chemical messenger produced by an endocrine or ductless gland that is released into the bloodstream and carries signals to target organs or tissues, exerting effects on various physiological processes.
Step 3
State two ways in which hormones are similar to the group of substances referred to in (b)(i).
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Answer
Both hormones and plant growth regulators (auxins) are involved in signaling processes that influence growth and development in organisms.
Both are produced in one location and can have effects in different areas of the organism, often leading to prolonged effects.
Step 4
What is meant by feedback in relation to hormone action?
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Feedback in relation to hormone action refers to a regulatory mechanism whereby the level of a hormone influences its own production or the production of another hormone. It serves to maintain homeostasis within the body.
Step 5
Give a brief account of the feedback mechanism for a named hormone.
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Answer
For example, insulin serves as a feedback hormone. When blood glucose levels rise after eating, the pancreas secretes insulin, which facilitates the uptake of glucose by cells, leading to a decrease in blood glucose levels. As glucose levels normalize, the secretion of insulin decreases, maintaining homeostasis.
Step 6
Describe one deficiency symptom of a named hormone.
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Answer
A deficiency of insulin can lead to diabetes mellitus, characterized by elevated blood glucose levels, excessive thirst, frequent urination, and fatigue.
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