The deficiency of vitamin B₁ (thiamine) leads to: MCQ with Answer and Explanation

Explanation:
Accommodation involves lens shape change via ciliary muscles. The blind spot lacks photoreceptors; fovea has high cone density; pupil adjusts via iris.

Explanation:
Metabolism, comprising anabolism and catabolism, is a universal feature of all living cells. Non-living objects may possess mass, crystallize, or conduct electricity, but they lack metabolic processes. Metabolism involves enzyme-catalyzed biochemical reactions that sustain life. Thus, metabolic activity is a definitive characteristic of life.

Explanation:
Digestion converts complex, insoluble food molecules into simple, soluble forms that can be absorbed. It involves mechanical action (chewing, churning) and enzymatic hydrolysis. Absorption is the uptake of nutrients, assimilation is incorporation into body tissues, egestion is elimination of undigested waste.