A Levels Biology (9700)•9700/13/M/J/21
Explanation
Cellular structures that contain DNA Steps:
- Identify mitochondria: they have circular mtDNA for independent replication and energy functions.
- Identify chloroplasts: they have circular cpDNA for photosynthesis and own gene expression in plant cells.
- Identify nucleolus: it is a RNA-protein complex for rRNA processing, lacking its own DNA.
- Identify centrioles: they consist of microtubules for spindle formation, containing no DNA.
Why no option is fully correct:
- The structures with DNA are 1 and 2 only; no choice lists exactly that.
Why the others are wrong:
- A includes 3, which has no DNA.
- B includes 4, which has no DNA.
- C includes 3, which has no DNA.
- D lacks 1 and includes 4, both errors.
Final answer: 1 and 2
Topic: Cells as the basic units of living organisms
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