The human embryo gets nutrition from the mother through the: MCQ with Answer and Explanation

Explanation:
The pineal gland is a small endocrine gland in the brain that secretes melatonin, a hormone that regulates circadian rhythms and sleep-wake cycles. Melatonin production is influenced by light exposure: it increases in darkness and decreases in light. The pituitary is the master gland, thyroid regulates metabolism, adrenal secretes adrenaline.

Explanation:
The ball and socket joint (e.g., glenohumeral, hip) allows movement in multiple axes (flexion, extension, abduction, adduction, rotation). The rounded head of one bone fits into the cup-shaped socket of another. Hinge (elbow, knee) allows movement in one plane, pivot (neck) allows rotation, gliding (wrist) allows sliding.

Explanation:
During the light reactions of photosynthesis, photolysis of water occurs at photosystem II, splitting water into protons, electrons, and molecular oxygen. The oxygen comes from water, not CO₂. This was demonstrated by using isotopically labeled oxygen (H₂O¹⁸). Glucose is formed in the Calvin cycle. Chlorophyll absorbs light but does not provide oxygen. The overall equation: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O.