AP Exam Prep · AP Biology
AP Biology Unit 6 Practice Test: Gene Expression and Regulation
Unit 6 follows information from DNA to protein and shows how cells control which genes are used. It also covers what mutations do and how biotechnology reads and changes DNA.
- Exam weighting:
- 12–16%
- Questions:
- 12 multiple choice
- Time:
- about 16 minutes
- Cost:
- Free, no sign-up
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What AP Bio Unit 6 covers
Unit 6, Gene Expression and Regulation, makes up 12–16% of the multiple-choice section and usually takes ~18–20 class periods. These are the topics in the current course framework, and every question in the test above is tagged with one of them.
- 6.1DNA and RNA Structure
- 6.2DNA Replication
- 6.3Transcription and RNA Processing
- 6.4Translation
- 6.5Regulation of Gene Expression
- 6.6Gene Expression and Cell Specialization
- 6.7Mutations
- 6.8Biotechnology
Unit 6 key ideas
Replication is semiconservative
Each new DNA molecule keeps one original strand. DNA polymerase only adds nucleotides to a 3′ end, so one strand is made continuously and the other in fragments.
Transcription and translation
RNA polymerase builds mRNA from the template strand. In eukaryotes the mRNA gets a cap and tail and introns are removed. Ribosomes read codons, and tRNA anticodons bring the matching amino acids.
Genes are switched on and off
Operons let bacteria respond quickly: the lac operon turns on when lactose is present, and the trp operon turns off when tryptophan is plentiful. In eukaryotes, transcription factors make cell types different.
Mutations and biotechnology
Substitutions may change one amino acid or none; insertions and deletions can shift the reading frame. Gel electrophoresis separates DNA by size, with small fragments moving farthest.
Common Unit 6 mistakes
- Writing the complement of DNA with T instead of U when making mRNA.
- Reading the template strand instead of the mRNA when translating codons.
- Thinking DNA fragments move toward the negative electrode; DNA is negatively charged and moves toward the positive one.
How to study this unit
- Label 5′ and 3′ ends on every sequence you write.
- For operon questions, decide first whether the repressor is bound to the operator.
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About these questions
StudyCoach wrote these questions for this test. Each one is mapped to a topic in the College Board's current AP Biology course framework. Every answer key was also checked by a separate AI review, and any disagreement was rechecked by hand. They have not yet been reviewed by an AP Biology teacher. If you think an answer is wrong, email support@studycoach.io.
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