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Marlow Works

AP Biology / Unit 7

Unit 7 · 13–20%

Natural Selection

Populations change when heritable traits affect reproductive success.

Start first lessonUnit practice

Topics

  • Variation and heritability
  • Selection
  • Population genetics
  • Speciation and evidence

Lessons

Key terms

Original practice

Marlow Works questions. If this unit does not have its own items yet, you will see other questions from the same course.

1 of 1Natural Selection · hard · free response

A beetle population includes both green and brown individuals. After several dry years, brown beetles become more common on exposed soil. In a short response, explain how mutation, variation, and selection together account for the change, and identify one condition that would prevent the population from evolving further in this trait.

Original Marlow Works item — not a College Board question.

Take your time—this is practice, not a test.

Review checklist

  1. 01Write a selection explanation that names trait, advantage, and heritability.
  2. 02Avoid the sentence “they adapted because they needed to.”
  3. 03Use one line of evidence (fossils, molecules, or anatomy) in a short argument.

Related resources

External links with reuse status. Marlow Works is independent and does not copy restricted exam or textbook material.

  • Official / link only

    AP Biology course page

    Official eight-unit framework, science practices, and lab resources.

    College Board · All rights reserved · accessed 2026-10-01

    Open source

  • Reference only — do not copy

    OpenStax Biology 2e

    Biology reference with commercial-use restrictions on the current publisher page.

    OpenStax · CC BY-NC-SA 4.0 with additional restrictions · accessed 2026-10-01

    Link only unless permission is obtained.

    Open source