Look at how the dna and rna complement each other. which dna base does the u in rna pair with? how is this different from the base pairing rules for dna?

The DNA base adenine (A) pairs with  uracil (U). This is different because in DNA adenine (A) pairs with thymine (T).

An ecosystem is in a certain area and includes living and non living plus there is weather conditions and a biome is a large amount of area with similar climate.so ecosystem is based on weather and biome is based on the average climate