Released STAAR Biology EOC · 2026 · Item 5 · 2 points

Walkthrough: Biology 2026, Item 5

B.7A · DNA Structure · unscored study

A nucleotide model shows a phosphate group connected to a pentose sugar. A line leading from the sugar ends in a question mark for the missing component. — Incomplete DNA nucleotide modelOriginal visual from the released STAAR test.

A DNA nucleotide has three components. This model of a nucleotide is missing one of these components. Identify the missing nucleotide component, AND explain the significance of this component in determining the traits of an organism.

Response format: written short response (2 points).

1. Understand the question

A nucleotide has three parts: a phosphate, a sugar, and a nitrogenous base. Find which part is missing from the model, then connect it to traits.

Try the question on your own first, then reveal one step at a time.

2. Solve it step by step

Practice released items for this skill Back to the lesson

Question, artwork, answer key and rationale: Texas Education Agency released STAAR test. Walkthrough steps written by TEKSForge. Studying here does not change your mastery or scores.