Question

each dna nucleotide is made up of three parts: a deoxyribose sugar, a phosphate group, and a nitrogenous base. dna has four kinds of nitrogenous bases: adenine, thymine, cytosine, and guanine.
individual nucleotides combine in long chains to form strands, and two strands of dna nucleotides join together to form the twisted ladder structure of a dna molecule.
this model shows part of a dna molecule.
image of dna double helix with labels: deoxyribose sugar, phosphate group, nitrogenous bases (a, t, g, c)
complete the paragraph.
many nucleotide dropdown combine to form the biological dropdown called dna. dna’s typical structure is described as a twisted ladder, or dropdown helix. the two sides of the dna ladder are made of dropdown and dropdown, and the inner rungs of the ladder are made of dropdown.

Explanation:

1. First blank: From the text "Individual nucleotides combine in long chains to form strands", so "molecules" (since nucleotides are molecules) or "units" but more accurately, the first part: "Many nucleotide molecules (or 'units') combine...", but from the context of DNA structure, nucleotides are the building blocks, so first blank: "molecules" (or "units", but the correct term here is that nucleotides (as molecules) combine. Wait, the first sentence: "Individual nucleotides combine in long chains to form strands, and two strands of DNA nucleotides join together...". So the first blank: "molecules" (or "units")? Wait, the sentence structure: "Many nucleotide [blank] combine to form the biological [blank] called DNA." So nucleotides are the monomers, so "molecules" (nucleotide molecules) combine to form the polymer (DNA, which is a nucleic acid, a type of molecule). Wait, the second blank: "molecule" (since DNA is a molecule). Then "DNA's typical structure is described as a twisted ladder, or double helix (since DNA is a double helix). The two sides of the DNA ladder are made of deoxyribose sugar and phosphate groups (from the diagram: deoxyribose sugar and phosphate group are the sides), and the inner rungs are made of nitrogenous bases (adenine, thymine, cytosine, guanine, which pair to form the rungs).

Let's fill each blank:

1. First blank: "molecules" (nucleotide molecules combine)
2. Second blank: "molecule" (DNA is a biological molecule)
3. Third blank: "double" (DNA is a double helix)
4. Fourth blank: "deoxyribose sugar" (one of the sides)
5. Fifth blank: "phosphate groups" (the other part of the sides)
6. Sixth blank: "nitrogenous bases" (the rungs)

Let's verify with the text: "Individual nucleotides combine in long chains to form strands, and two strands of DNA nucleotides join together to form the twisted ladder structure of a DNA molecule." So "Many nucleotide molecules combine to form the biological molecule called DNA. DNA's typical structure is described as a twisted ladder, or double helix. The two sides of the DNA ladder are made of deoxyribose sugar and phosphate groups, and the inner rungs of the ladder are made of nitrogenous bases."

Answer:

1. molecules
2. molecule
3. double
4. deoxyribose sugar
5. phosphate groups
6. nitrogenous bases