The genetic material in humans is organized as: MCQ with Answer and Explanation

Explanation:
Chlorophyll a is the primary photosynthetic pigment found in all algae and is essential for the light reactions of photosynthesis. Different groups of algae also contain other accessory pigments like chlorophyll b, c, phycobilins (phycocyanin, phycoerythrin), and carotenoids (fucoxanthin), which give them their characteristic colors (green, red, brown) and help in capturing light energy.

Explanation:
Oxytocin, produced in the hypothalamus and released from the posterior pituitary, triggers the milk let-down reflex by causing myoepithelial cells around alveoli to contract upon suckling. Prolactin stimulates milk synthesis. Estrogen and progesterone are involved in breast development during pregnancy but not the immediate ejection reflex.

Explanation:
Melatonin is a hormone secreted by the pineal gland, a small endocrine gland located in the brain. Its secretion is highly sensitive to light and dark cycles, being produced in higher amounts at night. Melatonin is crucial for regulating the circadian rhythm (sleep-wake cycle), maintaining biological clocks, and influencing seasonal reproductive functions in some animals. Thymosin is from the thymus, oxytocin from the posterior pituitary.