In genetic code, how many codons code for the amino acid tryptophan? MCQ with Answer and Explanation

Explanation:
Phyllotaxy is the pattern of leaf arrangement on the stem. In sunflower (and many other plants like mustard), the phyllotaxy is alternate, meaning a single leaf arises at each node. In opposite phyllotaxy (e.g., guava), two leaves arise at a node, and in whorled (e.g., Nerium), more than two leaves arise at a node.

Explanation:
Stomata are microscopic pores typically on the lower epidermis of leaves, bounded by two guard cells that regulate opening and closing for gas exchange (CO₂ in, O₂ out) and transpiration. Lenticels are on bark, hydathodes release water droplets (guttation), sclereids are thick-walled sclerenchyma cells. Stomatal density varies with environmental conditions.

Explanation:
Louis Pasteur developed the first rabies vaccine in 1885, using dried spinal cords from infected rabbits. Jenner developed smallpox vaccine, Koch identified tuberculosis bacterium, Salk developed inactivated polio vaccine.