Final answer:
For a DNA sequence, its complementary strand is determined by the base pairing rules where A pairs with T and C pairs with G. For the example sequence 5'-ATTCCGGATCGA-3', its complementary strand is 5'-TAAGGCCTAGCT-3'. Secondary DNA structures depend on more detailed sequence analysis.
Step-by-step explanation:
The initial question asks to determine which type of secondary structure a DNA sequence might form. To answer this, we must recognize that secondary structures in DNA are determined by base pairing. For the DNA sequence 5'-CGTTACGTATAACGTAACG-3', its complementary strand, based on standard base pairing rules, would be 3'-GCAATGCATATTGCATTGC-5'. However, determining secondary structure such as hairpins or loops requires more complex analysis not provided here. Typically, sequences form secondary structures if they have inverted repeats or other characteristics that promote folding back and intramolecular base pairing.
If we discuss the example sequence 5'-ATTCCGGATCGA-3', we can use the base pairing rule which states that adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G), to find its complementary sequence. Following this rule:
A is complementary to TC is complementary to GG is complementary to CT is complementary to A
Therefore, the complementary strand for the provided DNA sequence is 5'-TAAGGCCTAGCT-3', which corresponds to option A.