How are the bases in dna like a four latter alphabet

Which element forms an ionic bond with flourine? 1) fluorine 2) carbon 3) potassium 4) oxygen

The organism shown is a free-living one that is anchored to the bottom of ponds and streams during one stage of its life cycle what is the common name for the group to which this organism belong

Quickly what are the following of organisms that existed over a wide area but only for a limited time period called a.soft fossils b.mold fossils c.index fossils d.trace fossils