The concept of 'survival of the fittest' was proposed by: MCQ with Answer and Explanation

Explanation:
The stomach secretes gastric juice containing hydrochloric acid and the enzyme pepsin, which initiates the digestion of proteins into smaller peptides. The small intestine is the primary site for the final digestion of food and the absorption of most nutrients (amino acids, simple sugars, fatty acids, vitamins) into the bloodstream through its villi. The large intestine (colon) primarily absorbs water, electrolytes, and some vitamins produced by gut bacteria, forming solid feces. All statements are correct.

Explanation:
Vitamin E (tocopherol) is a fat-soluble antioxidant that protects cell membranes from lipid peroxidation. Vitamin C is water-soluble antioxidant, A is for vision, D for calcium.

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.