arbon, as with many elements, can arrange its atoms into several different geometries, or "allotropes." In pure diamond, every carbon atom is covalently bonded to exactly 4 other carbon atoms in a very specific and energetically favorable geometry. The diamond cannot be broken or scratched unless many covalent bonds are broken, which is difficult to do. In another common allotrope, graphite, every carbon atom is covalently bonded to only 3 other carbon atoms, and the atoms are arranged in sheets that are not covalently bonded to each other. The sheets can be broken apart easily, ultimately meaning that graphite can be easily scratched. Coal is composed of particles of different allotropes of carbon, and some "amorphous carbon," which has no defined geometry in its atomic structure. Without a continuous network of covalent bonds, coal is easily scratched (i.e. it is not hard).
DNA is being used as a template to make a molecule of mRNA.
<span>Simple.
All of the millions of different life forms (the diversity of life) have come about by natural selection, whereby random mutations in the genes have either succeeded or failed.
But all life can be traced back to a common single-celled origin. Thus we have the unity of life where we (possibly) share more than 50 % of our DNA with a crocodile.eg:analogous organs, homologous organs.</span>
A cross between two different lines and/ or genes that differ in two observed traits.
