The gland responsible for regulating circadian rhythms is the: MCQ with Answer and Explanation

Explanation:
Approximately 97% of O₂ is transported bound to hemoglobin (as oxyhemoglobin), while only 3% is dissolved in plasma. Each hemoglobin molecule can bind four O₂ molecules cooperatively. CO₂ is mainly transported as bicarbonate (70%), carbaminohemoglobin (23%), and dissolved (7%). The affinity of hemoglobin for O₂ is influenced by pH, CO₂, and temperature (Bohr effect).

Explanation:
Prolactin, from the anterior pituitary, promotes mammary gland development and milk synthesis. Oxytocin triggers milk ejection. Estrogen and progesterone prepare breasts during pregnancy but inhibit milk secretion.

Explanation:
Diatomaceous earth is a siliceous, sedimentary rock formed from the fossilized remains of diatoms. Diatoms have unique, highly resistant cell walls called frustules, made of hydrated silicon dioxide (silica). Over millions of years, these frustules accumulate on ocean and lake floors, forming diatomaceous earth, which has numerous industrial applications due to its abrasive and porous nature.