Thyroxine, secreted by the thyroid gland, primarily regulates: MCQ with Answer and Explanation

Explanation:
Beriberi results from lack of thiamine (B₁), affecting the nervous and cardiovascular systems. It manifests as dry beriberi (peripheral neuropathy) or wet beriberi (heart failure). Pellagra is niacin deficiency, scurvy vitamin C, rickets vitamin D. Thiamine is a coenzyme in carbohydrate metabolism.

Explanation:
Oxytocin is a peptide hormone produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. In females, it has two major roles: 1) During childbirth, it stimulates powerful contractions of the uterine smooth muscle, facilitating labor and delivery (this is a positive feedback loop). 2) During lactation, it stimulates the contraction of myoepithelial cells surrounding the alveoli in the mammary glands, causing the ejection (let-down) of milk into the ducts in response to suckling. It does not produce milk; prolactin does that.

Explanation:
The platypus is a monotreme (egg-laying mammal) with a duck-like beak, no teeth, and webbed feet. Bats and whales are placental mammals, kangaroo is a marsupial. Platypus is found in Australia.