Penguins and orcas are both black and white, have developed fins for rapid swimming and are able to tolerate cold water, but penguins are birds and orcas are mammals so they are not closely related organisms; thus, their shared features are an example of:

Analogous structures

Explanation:

Analogous structures are structures that are similar, found in different species organisms that do not share a common ancestral origin. Analogous structures are evolved independently by unrelated species as a result of having being subjected to similar environmental conditions in their different place of dwelling. The features shared by Penguins and orcas, which are similar in function, are an example of analogous structures, since both do not have the same origin.

littering streams           is the answer

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides