Question

weak attractive forces, called hydrogen bonds, form between the nitrogenous bases to hold the two strands together and form the rungs of the dna molecule’s ladder structure. unlike covalent bonds, weak hydrogen bonds can be easily broken. complete the paragraph. the structure of a dna molecule resembles a twisted ladder. the sides of the ladder, or the backbones of the molecule, are formed by blank bonds between the phosphate groups and the blank. the rungs of the ladder are formed by blank bonds between the blank. (options: strong hydrogen, weak hydrogen, strong covalent, weak covalent, deoxyribose sugars, nitrogenous bases)

Explanation:

• DNA's backbone (sides of the ladder) is made of alternating deoxyribose sugars and phosphate groups, connected by strong covalent bonds (these are stable, strong bonds).
• The "rungs" of the DNA ladder are formed by pairs of nitrogenous bases (A - T, G - C), connected by weak hydrogen bonds (these are weaker, allowing DNA to unzip for replication/transcription).

Using the diagram and knowledge of DNA structure: the backbone uses deoxyribose sugars, covalent bonds (strong) link sugar - phosphate, and hydrogen bonds (weak) link the nitrogenous base pairs.

Answer:

1. The first blank (bonds between the phosphate groups and the ______): deoxyribose sugars
2. The second blank (formed by ______ bonds): strong covalent
3. The third blank (bonds between the phosphate groups and the deoxyribose sugars and the ______): nitrogenous bases
4. The fourth blank (formed by ______ bonds): weak hydrogen