Question

Which of the statements are true of endosymbiotic theory?

a) explains the origin of all organelles found within a eukaryotic cell

b) provides insight about why chloroplasts can survive outside of a eukaryotic cell

c) explains the origin of some eukaryotic organelles, such as mitochondria

d) explains why chloroplasts contain circular DNA similar to bacteria

e) states that an ancestral eukaryotic cell engulfed a photosynthetic protobacteria

Answer 1

C, D, E (A is partially correct)

Option A is partially correct because endosymbiotic theory does not have a conclusive evidence for all the Eukaryotic organelles. Strong evidences are present for mitochondria and chloroplast.

Endosymbiotic theory explain the origin of Eukaryotic organisms like mitochondria and chloroplast. The evidences with support the endosymbiotic origin of Mitochondria and chloroplast are strong but the evidences with support the origin of other Eukaryotic organelles like lysosomes and vacuoles are not that conclusive.

According to this theory, and ancestral Eukaryotic cell engulfed a photosynthetic bacteria which then lost some of its genes and gained from new genes in order to become mitochondria and chloroplast.

Both bacteria, and mitochondria and chloroplast have a circular double stranded molecule of DNA. All these have 70s type of ribosomes.

The bacteria which was capable of performing aerobic respiration evolved into mitochondria and the one which was able to perform photosynthesis evolved into chloroplast.

Both mitochondria, chloroplast and bacteria are able to undertake phosphorylation and electron transport chain in their membranes.

All these evidences support the endosymbiotic origin of Mitochondria and chloroplast and some other Eukaryotic organelles as well.

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