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AP Biology MCQs

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AP Biology practice questions by unit

Fiveable has 21,183 AP Biology multiple-choice practice questions across 8 units, plus 274 stimulus-based question sets built around a source. Practice one unit or topic at a time.

  • Unit 1 – Chemistry of Life: 1,351 multiple-choice questions, 35 stimulus sets
  • Unit 2 – Cells: 3,496 multiple-choice questions, 56 stimulus sets
  • Unit 3 – Cellular Energetics: 1,808 multiple-choice questions, 27 stimulus sets
  • Unit 4 – Cell Communication and Cell Cycle: 2,159 multiple-choice questions, 26 stimulus sets
  • Unit 5 – Heredity: 1,699 multiple-choice questions, 20 stimulus sets
  • Unit 6 – Gene Expression and Regulation: 2,730 multiple-choice questions, 31 stimulus sets
  • Unit 7 – Natural Selection: 4,568 multiple-choice questions, 48 stimulus sets
  • Unit 8 – Ecology: 3,372 multiple-choice questions, 31 stimulus sets

Sample AP Biology practice question

A wind-pollinated plant species spreads to a nearby island where flowering begins 3 weeks earlier than on the mainland. Over many generations, island plants rarely exchange pollen with mainland plants even when seeds occasionally arrive by storms. What evidence best supports a claim that speciation is occurring through reproductive isolation?

Different flowering times reduce gene flow, allowing allele frequencies to diverge over time

Correct answer

Different flowering times increase gene flow, keeping allele frequencies similar across habitats

Different flowering times only change plant size, so reproductive isolation cannot develop over time

Different flowering times completely stop mutations, preventing island and mainland populations from diverging

Explanation

Linking reproductive timing to reduced pollen exchange supports a mechanism for decreased gene flow. With limited interbreeding, natural selection and drift can change allele frequencies independently on the island and mainland.

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