It has been hypothesized that chloroplasts originate from photosynthetic cyanobacteria that became symbiotic inside a host cell.Which of the following observations provides the strongest evidence for this suggestion.
A. Microscopically, chloroplasts appear similar to cyanobacteria
B.Chloroplast DNA show clear similarities to cyanobacterial DNA.
C.Both chloroplas and cyanobacteria are green and perform photosynthesis.
D.Photosynthetic cyanobacteria and fungi form mutualistic association in lichen.
I think the correct answer is B.
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Yes, you are correct. The answer is B.
To arrive at this answer, we need to examine the different options and evaluate them based on the strength of the evidence they provide.
A. Microscopically, chloroplasts appear similar to cyanobacteria: While this observation is interesting, it is not strong evidence on its own. Similar appearances could be coincidental or due to convergent evolution.
B. Chloroplast DNA shows clear similarities to cyanobacterial DNA: This observation provides stronger evidence because it suggests a potential genetic connection between chloroplasts and cyanobacteria. If the DNA of chloroplasts shows clear similarities with cyanobacterial DNA, it indicates a shared evolutionary history or a symbiotic relationship.
C. Both chloroplasts and cyanobacteria are green and perform photosynthesis: This observation is not conclusive evidence because many organisms can perform photosynthesis and be green. In addition, the color green alone does not provide information about the genetic or evolutionary relationship between chloroplasts and cyanobacteria.
D. Photosynthetic cyanobacteria and fungi form mutualistic associations in lichens: This observation is unrelated to the true origin of chloroplasts. Lichen is a completely different symbiotic association involving a fungus and a photosynthetic partner, which can be different types of algae or cyanobacteria.
By considering each option, we can conclude that the strongest evidence for chloroplasts originating from photosynthetic cyanobacteria is the clear similarities between chloroplast DNA and cyanobacterial DNA (option B).