Which of the following organelles have their own DNA and ribosomes?
- A.Endoplasmic reticulum and Golgi bodies
- B.Mitochondria and Chloroplast
- C.Endoplasmic reticulum and cytoskeleton
- D.Cell wall and nucleolus
Correct answer
Explanation
The correct answer is B, Mitochondria and Chloroplast. These two organelles carry their own circular DNA and their own small (70S) ribosomes, so they can make some of their own proteins.
Mitochondria, the sites of aerobic respiration, and chloroplasts, the sites of photosynthesis, are therefore called semi-autonomous organelles. Both are bounded by a double membrane and multiply by dividing, much like bacteria. Their bacterial-type DNA and 70S ribosomes support the endosymbiotic theory, which holds that they began as free-living bacteria taken in by an ancestral cell: mitochondria from aerobic bacteria and chloroplasts from cyanobacteria. Mitochondrial DNA is inherited only from the mother, which is why it is used in tracing maternal lineage.
A is wrong because the endoplasmic reticulum and Golgi bodies have no DNA of their own. C is wrong because the cytoskeleton is a network of protein fibres with no DNA or ribosomes. D is wrong because the cell wall is a non-living layer and the nucleolus makes ribosomal RNA but is not a separate organelle with its own genome.
Exam tip: Semi-autonomous organelles: mitochondria and chloroplasts, with own DNA and 70S ribosomes.
Practice Questions
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- A.Refractometer
- B.Galvanometer
- C.Viscometer
- D.Diffractometer
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Read the full explanation →Reverberation is a phenomenon associated with a
- A.multiple refraction of sound.
- B.multiple reflection of sound.
- C.single refraction of sound.
- D.single reflection of sound.
Show answer
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Read the full explanation →Which one of the following is NOT a basic property of electric charge ?
- A.Charges can be added
- B.Charge is conserved
- C.Charge on a body is always an integral multiple of an electron or a proton charge
- D.Charges can be created and destroyed in an isolated system
Show answer
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Read the full explanation →Which one of the following statements is NOT correct ?
- A.All proteins are enzymes
- B.Mostly enzymes are proteins
- C.All fats are energy rich compounds
- D.Glucose is a common carbohydrate
Show answer
This statement is false: enzymes are mostly proteins, but most proteins are not enzymes. Proteins do many jobs in the body.
Read the full explanation →Which one of the following types of radiations has the smallest wavelength?
- A.Microwaves
- B.Infra-red
- C.Visible light
- D.X-rays
Show answer
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Read the full explanation →