The scientist who discovered the antibiotic streptomycin was: MCQ with Answer and Explanation

Explanation:
Polygenic inheritance is when multiple genes (polygenes) contribute to a single trait, resulting in continuous variation. Human skin color is controlled by at least three genes, showing a spectrum of phenotypes. Pleiotropy is one gene affecting multiple traits. Multiple alleles refer to more than two alleles for a gene (e.g., ABO blood groups). Co-dominance is when both alleles express equally.

Explanation:
Rabi crops are sown in winter (October-December) and harvested in spring (March-April). Wheat, gram, mustard, pea are common rabi crops. Rice, maize, and sugarcane are kharif crops, sown with the onset of monsoon and harvested in autumn. This distinction is based on seasonal cultivation patterns in Indian agriculture. Rabi crops require cool growing season and warm harvest season.

Explanation:
The tundra biome, found in Arctic and Antarctic regions, has permanently frozen subsoil (permafrost), extremely low temperatures, short growing seasons, and vegetation limited to mosses, lichens, grasses, and dwarf shrubs. Taiga is the boreal coniferous forest, savanna is tropical grassland, temperate deciduous forest has distinct seasons. Tundra is the coldest biome.