Question

Which of the following is evidence for the endosymbiotic theory?
A) Eukaryotic cells have DNA
B) Eukaryotic cells have organelles
C) The mitochondria and chloroplast have their own DNA
D) Prokaryotic cells are typically larger than eukaryotic cells.

Answer 1

Hint:According to the endosymbiotic theory, eukaryotic cells evolved by taking prokaryotic cells. This was a beneficial or mutually symbiotic relationship, and over time, the prokaryotic cells lost many of their other functions, becoming integral parts of the bigger cell.

Complete answer:
>All living cells have DNA, whether they are prokaryotic or eukaryotic cells. This includes the bacteria, Archaea, plants, algae, protozoans and higher animals. Option A is incorrect.
>Eukaryotic cells have a number of intracellular organelles designed for specific functions, like Golgi bodies for intracellular transport, but this is not evidence of them having existed as separate cells that were then engulfed by the eukaryotic cell. Option B is not correct.
>Mitochondria and Chloroplast both have their own DNA and are able to replicate/divide independently of the main cell. This supports the theory that eukaryotic cells engulfed photosynthetic and chemosynthetic prokaryotes at some point in evolution. Option C is the correct answer.
>Option D is not correct. A prokaryotic cell is typically smaller than a eukaryotic cell. Being smaller in size, they can manage intracellular functions without the need for organelles.

Virus falls outside the purview of either kind of cell. As they are unable to exist, carry out any metabolic functions, or reproduce without the host, they are called particles, and not cells. However, as they depend on a host for survival and reproduction, evolutionarily they are younger than either cell type.

Hence the correct answer is option ‘C’.

Note:Eukaryotic cells include the presence of intracellular organelles, the presence of a membrane bound nucleus, both features of which are absent in prokaryotic cells. Bacteria and Archaea are prokaryotes.