Select the descriptions of the ways hydrocarbon skeleton structures may vary.

Given the following choices

A.position of the carbon-carbon double bonds

B.presence of enclosed carbon atom rings

C.branching of the carbon chain

D.length of the carbon chain

The answers are; B, C & D.  Carbon is a versatile atom (with a valence of +4) and is able to bond with other elements and other carbon atoms in different ways. It can form linear and  branching chains of varying lengths. It can form double and single bonds with elements and form rings such as the deoxyribose sugars.

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

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