The 'Blood-Brain Barrier' (BBB) is formed primarily by the tight junctions between the endothelial cells of capillaries in the brain and the surrounding: MCQ with Answer and Explanation

Explanation:
Acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) reacting with atmospheric water to form acids. Biological Oxygen Demand (BOD) measures the amount of oxygen required by microbes to decompose organic matter, indicating water pollution levels. Eutrophication (nutrient enrichment) causes algal blooms, depleting oxygen and killing aquatic life, thereby decreasing biodiversity. Thus, statements 1 and 2 are correct.

Explanation:
The Munch hypothesis, or mass flow hypothesis, explains the translocation of organic solutes (primarily sucrose) through the phloem. It proposes that the movement is driven by a turgor pressure gradient between the source (where sugars are loaded into the phloem, increasing osmotic pressure) and the sink (where sugars are unloaded, decreasing osmotic pressure). Water flows from xylem to phloem and back, driving the bulk flow.

Explanation:
A sarcomere is the segment between two Z-lines (Z-discs) and is the basic contractile unit of skeletal and cardiac muscle. It contains actin (thin) and myosin (thick) filaments. Sarcolemma is the plasma membrane, sarcoplasm is cytoplasm, myofibril is a bundle of contractile filaments. Shortening of sarcomeres leads to muscle contraction per sliding filament theory.