There is evidence that the composition of the earth's atmosphere is still changing. one possible reason is that many power stations generate electricity by burning fossil fuels such as coal, oil or natural gas. sulphur dioxide, SO2, is produced when coal burns in air. what environmental problem does sulphur dioxide cause?

Dna, in the nucleus carries the genetic code for making proteins in ribosomes. in the diagram, b, represents the proteins produced. dna cannot leave the nucleus to carry the genetic information to the ribosome where proteins are produced. how does the genetic code get from the nucleus to the ribosome? what does a represent? now