Consider statements about cell biology: 1. The Golgi apparatus packages materials for secretion. 2. The smooth ER is involved in lipid synthesis. 3. The rough ER is involved in lipid synthesis. Which are correct? MCQ with Answer and Explanation

Explanation:
A food web is a complex network of interconnected food chains showing multiple feeding relationships in an ecosystem. Decomposers (bacteria and fungi) break down dead organic matter, returning essential nutrients to the soil for producers. Due to energy loss at each transfer (10% law), the total biomass generally decreases at higher trophic levels, forming an upright pyramid. All statements are correct.

Explanation:
Birds (Aves) and mammals (Mammalia) are endothermic (warm-blooded) and possess a four-chambered heart, allowing complete separation of oxygenated and deoxygenated blood. Amphibians have a three-chambered heart, reptiles mostly three-chambered (except crocodilians), fish two-chambered. This allows high metabolic rates.

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.