In mammals the parathyroid gland secretes parathyroid hormone (PTH) - VCE - SSCE Biology - Question 23 - 2008 - Paper 1
Question 23
In mammals the parathyroid gland secretes parathyroid hormone (PTH). PTH is involved in regulating the concentration of calcium in blood plasma. Parathyroid hormone ... show full transcript
Worked Solution & Example Answer:In mammals the parathyroid gland secretes parathyroid hormone (PTH) - VCE - SSCE Biology - Question 23 - 2008 - Paper 1
Step 1
A. increased production of PTH results in reduction of vitamin D activation.
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Answer
This statement is incorrect. Increased PTH actually enhances the activation of vitamin D, leading to increased calcium absorption in the intestine.
Step 2
B. reduced production of PTH results in increased calcium in the faeces.
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Answer
This statement is correct. When PTH production decreases, less calcium is reabsorbed by the kidneys, leading to increased calcium excretion in the faeces.
Step 3
C. sustained overproduction of PTH results in strengthened bones.
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Answer
This statement is incorrect. Sustained high levels of PTH lead to increased calcium release from bones, which can weaken them over time rather than strengthen.
Step 4
D. high levels of blood calcium stimulate release of PTH.
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Answer
This statement is incorrect. High levels of blood calcium actually inhibit the release of PTH through negative feedback mechanisms.
