Organisms, like bacteria or lichen, that can live on bare rock and form soil are called.

Pioneer species

Explanation: Whenever a disturbed area or barren land starts to regenerate, the first organisms that come into play are the pioneer species. This is because they are able to grow on bare rock and break it down into soil, which is then suitable for small plants to grow. This is how succession takes place. Pioneer species are the part of the primary succession. They form the foundation of that habitat.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.