The cell wall of bacteria is primarily composed of: MCQ with Answer and Explanation

Explanation:
Mature mammalian red blood cells (erythrocytes) lose their nucleus and other organelles during development to maximize space for hemoglobin. Thus they are anucleate. They cannot divide or repair themselves and have a lifespan of about 120 days. Neurons, leukocytes, and hepatocytes are nucleated. RBCs obtain energy through anaerobic glycolysis.

Explanation:
The Blood-Brain Barrier (BBB) is a highly selective semipermeable border that protects the brain from many substances in the blood. It is primarily formed by the tight junctions between the endothelial cells of the brain's capillaries. These endothelial cells are closely associated with the foot processes of astrocytes (a type of glial cell), which induce and maintain the tight junctions, restricting the passage of large molecules, toxins, and pathogens into the brain tissue.

Explanation:
Cortisol (a glucocorticoid) from the adrenal cortex is a steroid hormone derived from cholesterol. Insulin and growth hormone are peptides, adrenaline is a catecholamine (amino acid derivative).