The term 'genetically modified organism' (GMO) refers to: MCQ with Answer and Explanation

Explanation:
The macula lutea is a yellowish spot near the center of the retina. Its central depression, the fovea centralis, is the point of sharpest vision. The fovea is packed exclusively with cone cells and lacks blood vessels and rods. This high density of cones, combined with the displacement of overlying retinal layers, allows for maximum visual acuity and color discrimination in bright light. The blind spot is the optic disc.

Explanation:
Auxin (indole-3-acetic acid) produced at the shoot apex suppresses the growth of lateral buds, a phenomenon called apical dominance. Removing the apex allows lateral buds to grow. Cytokinin promotes cell division and counteracts apical dominance. Gibberellin stimulates stem elongation, and ethylene is involved in fruit ripening and senescence. The auxin-cytokinin ratio determines root and shoot differentiation in tissue culture.

Explanation:
Vitamin B₁ (thiamine) is water-soluble and functions as a coenzyme (thiamine pyrophosphate) in carbohydrate metabolism, particularly in decarboxylation reactions. Vitamins A, D, E, and K are fat-soluble. B₁ deficiency causes beriberi and Wernicke-Korsakoff syndrome. Being water-soluble, excess is excreted in urine and toxicity is rare.