The hormone responsible for the ripening of fruits is: MCQ with Answer and Explanation

Explanation:
The pleura consists of visceral pleura (adhering to lungs) and parietal pleura (lining chest wall), with pleural fluid between them reducing friction during breathing. Pericardium surrounds the heart, peritoneum lines the abdominal cavity, meninges cover the brain and spinal cord.

Explanation:
Smooth muscle is non-striated, involuntary, and forms the muscular layer of the digestive tract (esophagus, stomach, intestines), responsible for peristalsis. Skeletal muscle is voluntary and striated, cardiac is heart-specific.

Explanation:
The pineal gland, a small endocrine gland located in the epithalamus of the brain, is often called the 'biological clock' or the 'third eye' in some lower vertebrates. Its primary function in humans is to secrete the hormone melatonin. Melatonin production is regulated by the light-dark cycle (circadian rhythm); it is produced in higher amounts during the night and suppressed by light. Melatonin helps regulate sleep-wake cycles, seasonal reproductive functions, and metabolism.