Answer: Contain their own DNA and ribosomes, enabling synthesis of some of their own proteins.
- A Replicate mainly when directed by chloroplast DNA in plant cells according to most studies
- B Contain their own DNA and ribosomes, enabling synthesis of some of their own proteins
- C Can move independently between cells without any external signal under usual circumstances
- D Function largely independently of any nuclear-encoded proteins in the majority of documented cases
Correct answer: B. Contain their own DNA and ribosomes, enabling synthesis of some of their own proteins
Explanation: Mitochondria possess their own circular DNA and ribosomes, allowing them to synthesize some of their own proteins, though they still depend on the nucleus for many other proteins, hence 'semi-autonomous'.
Aerobic respiration unfolds in three locations: glycolysis in the cytoplasm yields a small amount of ATP directly, the Krebs cycle in the mitochondrial matrix harvests electron carriers (NADH, FADH2), and the electron transport chain in the inner mitochondrial membrane uses those carriers to generate the bulk of the ATP, with O2 needed only at this final stage.
Concept context
Glycolysis, the Krebs cycle, the electron transport chain, fermentation, and the respiratory quotient. The cellular energy-release counterpart to photosynthesis.