Q.75 Which of the following cell organelle is regarded as semi-autonomous?
1. Chloroplast
2. Peroxisomes
3. Ribosomes
4. Lysosome
Semi-Autonomous Organelles: Chloroplast MCQ Answer
Semi-autonomous organelles contain their own DNA and ribosomes, enabling partial self-replication independent of the nucleus. Chloroplasts exemplify this in plant cells, crucial for NEET and CSIR NET biology exams.
Correct Answer
Option 1: Chloroplast is regarded as semi-autonomous.
Chloroplasts possess circular cpDNA, 70S ribosomes, and replicate via fission, synthesizing some proteins internally while relying on nuclear genes for full function.
Organelle Characteristics
Semi-autonomous nature stems from endosymbiotic origins, resembling prokaryotes with independent replication machinery.
Mitochondria share these traits, but among options, chloroplast fits perfectly for photosynthetic cells.
Option Analysis
| Option | Organelle | Explanation |
|---|---|---|
| 1 | Chloroplast | Correct; has own circular DNA, ribosomes, divides independently—hallmark of semi-autonomy in plants. |
| 2 | Peroxisomes | Incorrect; lack DNA/ribosomes, fully dependent on nuclear genes for enzymes like catalase. |
| 3 | Ribosomes | Incorrect; non-membrane bound, no DNA, rely entirely on nuclear mRNA—no autonomy. |
| 4 | Lysosome | Incorrect; single-membrane vesicles with hydrolytic enzymes, no genetic material or replication. |
Biological Significance
Chloroplasts enable photosynthesis autonomy while coordinating with nucleus for thylakoid proteins, highlighting semi-autonomous dynamics.
