In the endocrine system, the hormone 'Oxytocin' is synthesized in the hypothalamus but is stored and released by the:
A. Thyroid gland
B. Adrenal medulla
C. Posterior pituitary (Neurohypophysis)
D. Anterior pituitary
Answer: Option C
Solution (By JKSSB Mock Tests)
Oxytocin (and ADH/vasopressin) are peptide hormones synthesized by the neurosecretory cells of the hypothalamus (supraoptic and paraventricular nuclei). They are transported down the axons of these neurons and stored in the nerve terminals of the posterior pituitary (neurohypophysis). Upon neural stimulation, they are released directly into the bloodstream from the posterior pituitary. The anterior pituitary synthesizes its own hormones.
Explanation:
The Haversian system (osteon) is the characteristic structural unit of compact (cortical) bone in mammals. It consists of a central Haversian canal (containing blood vessels and nerves) surrounded by concentric layers of calcified matrix called lamellae. Between the lamellae are small spaces called lacunae, which house osteocytes (bone cells). Canaliculi connect the lacunae. Bird bones are pneumatic (hollow), and cartilage lacks Haversian systems.
Explanation:
Vitamin K and some B vitamins (like biotin) are synthesized by the normal microflora of the large intestine. However, the amount may be insufficient to meet total needs. Vitamin A, C, and D must be obtained from diet or sunlight. Gut bacteria contribute to vitamin K for clotting factors.
Explanation:
The correct taxonomic hierarchy in ascending order is: Species (lowest) → Genus → Family → Order → Class → Phylum (or Division in plants) → Kingdom (highest). Some classifications add Domain above Kingdom. This system groups organisms based on shared characteristics. Binomial nomenclature uses Genus and Species. Option A correctly places Family before Order.
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