Describe how first plant cells first got mitochondria and chlorplasts?

Question

Study guide question for my botany class please help?

Answer 1

The best evidence indicates at some point in the past, a primitive cell "ate" other living organisms but did not digest them.  The photosynthetic cell became a chloroplast and a non-photosynthetic cell became the mitochondria.   Both chloroplasts and mitochondria have ribosomes similar to bacterial ribosomes.  They also have a circular chromosome like those of bacteria.

There are giant clams, hydra, protozoans that have living algal cells within their bodies so the mode of obtaining the two organelles is entirely possible.

Answer 2

What?  Nobody knows that for sure, do they?

Answer 3

The explanation you are seeking is called the Endosymbiont Theory.  This theory states that chloroplast and mitochondria were originally free-living prokaryotic cells.  these small prokaryotic cells were consumed by larger phagocytic prokaryotic cells.  They were consumed by not digested.  Instead of being digested for energy, they remained in tact in the cells and produced ATP and glucose for the host cell.  Over time this symbiotic relationship became so highly evolved that the two prokaryotic cells can no longer be separated and thus eukaryotic cells evolved.

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