The hormone that stimulates the thyroid gland to release thyroxine is:
A. TSH
B. LH
C. ACTH
D. FSH
Answer: Option A
Solution (By JKExamLibrary)
Thyroid-stimulating hormone (TSH), secreted by the anterior pituitary, binds to receptors on thyroid follicular cells and stimulates them to produce and release T₃ and T₄. ACTH stimulates adrenal cortex, FSH and LH target gonads.
Explanation:
Parathyroid hormone (PTH) activates the enzyme 1-α-hydroxylase in the kidney, converting vitamin D to its active form, which then increases calcium absorption.
Explanation:
The Competitive Exclusion Principle, formulated by G.F. Gause based on his experiments with Paramecium, states that two species with identical ecological niches (competing for the exact same limited resources) cannot coexist indefinitely in the same habitat. One species will inevitably have a slight reproductive advantage and will outcompete the other, leading to the local extinction or evolutionary shift (resource partitioning) of the inferior competitor.
Explanation:
Iodine atoms are incorporated into thyroxine (T₄, 4 iodine atoms) and triiodothyronine (T₃, 3 iodine atoms) synthesized by thyroid follicular cells. Iodine deficiency leads to goiter and hypothyroidism. Iron is in hemoglobin, calcium in bones, phosphorus in ATP and bones.
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