Anatomy is the best answer
There are eight major terrestrial biomes: tropical rainforests, savannas, subtropical deserts, chaparral, temperate grasslands, temperate forests, boreal forests, and Arctic tundra. Biomes are large-scale environments that are distinguished by characteristic temperature ranges and amounts of precipitation
Because since developing countries are still growing, when they finally get to the level of some more advanced countries the country as a whole feels a "greater growth"
DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-OH of the existing strand for adding free nucleotides. DNA replication can take place both the directions chemically. ... But these nucleotide triphosphates hydrolyze spontaneously under aqeuous conditions.
An identical twin I think