In the human eye, the 'macula lutea' and its central depression, the 'fovea centralis', are significant because the fovea contains: MCQ with Answer and Explanation

Explanation:
Adventitious roots arise from stem, leaf, or other non-root tissues, unlike taproots and fibrous roots that develop from the radicle. Examples: prop roots of banyan, stilt roots of maize, aerial roots of orchids. They can serve support, aeration, or additional absorption.

Explanation:
Villi are microscopic finger-like projections on the inner lining of the small intestine, covered with microvilli (brush border), greatly increasing surface area for absorption of digested nutrients. Each villus contains a lacteal (lymph capillary) and blood capillaries. Alveoli are in lungs, nephrons in kidneys, cilia are hair-like projections on cells.

Explanation:
Fleming accidentally discovered penicillin in 1928 when a mold contaminant (later identified as Penicillium notatum/now Penicillium chrysogenum) inhibited bacterial growth. This led to the first widely used antibiotic. Aspergillus species produce some toxins and acids, Saccharomyces is yeast, Agaricus bisporus is the common mushroom. Penicillin acts by disrupting bacterial cell wall synthesis.