The bonds or interactions that hold together adjacent nucleotides in the sugar-phosphate backbone of DNA are .The bonds or interactions that hold together complementary bases from opposite strands of DNA are hydrogen bonds. The bonds or interactions between stacked nucleotide units that help hold the DNA molecule together are .

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.