In two to three sentences, describe one advanced search strategy and how it is useful.

Boolean searching:

Most searches will return too many or too few records. It takes a long time to look at hundreds of records. By putting a little effort into constructing search strings (what you type into the search box) you can save a lot of time. The database can do a lot of work for you if you take the trouble to add a little sophistication to your search strings.

To do this with databases you need to know about the Boolean system. By the use of a few simple linking words, called operators, you can make your searches much more precise.

Okay, biology isn't exactly my strongest subject (it never has been), but i'm pretty sure the answer is nucleotides. dna is made up of nucleotides. each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. there are four different nitrogen bases: adenine (a), thymine (t), guanine (g), and cytosine (c). a always pairs with t, and g always pairs with c.