Question

Mitochondria and chloroplast are regarded as endosymbionts because,
(a) They do not have de novo origin
(b) They both possess their own nucleic acids
(c) Their membranes are like those of prokaryotes
(d) All of the above

Answer 1

Hint: Endosymbiotic theory that small prokaryotes began living in larger or host cells. The inner membranes of both organelles have enzymes and transport systems that are homologous to those found in the plasma membranes of living primitive cells.

Complete step by step answer:
The endosymbiosis theory explains the origins of organelles such as mitochondria and chloroplasts into the eukaryotic cells. Mitochondria and chloroplasts organelles evolved from endosymbiotic bacteria. Heterotrophic prokaryotes were engulfed which functioned as mitochondria. Photosynthetic prokaryotes were engulfed which functioned as chloroplasts. Both mitochondria and chloroplast can work independently because of the presence of their own genetic materials.
So, the correct answer is, ‘They both possess their own nucleic acids.’

Additional information:
- Theory of endosymbiosis was first proposed by Lynn Margulis in the 1960s.
- Much evidence to support eukaryotic cellular respiration originated via endosymbiosis of aerobic purple bacteria which ultimately became mitochondria.
- Mitochondria and chloroplasts are thought to have evolved from engulfed prokaryotes that once lived as independent organisms.
- A eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryotic cell, gradually developing into a mitochondrion.
- Eukaryotic cells consisting of mitochondria then engulfed photosynthetic prokaryotes, which evolved to become specialized chloroplast organelles in the eukaryotic cell.
- The mitochondria is a double membrane-bound ATP producing system organelle found in all eukaryotic organisms.
- Chloroplasts specialized compartments, in plant and algal cells.
- The main role of chloroplasts is in photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts it and stores it in the energy- storage molecules ATP and NADPH while freeing oxygen from water.

Note:
- Primary endosymbiosis involves the engulfment of a bacteria by another free living eukaryotic organism.
- Secondary endosymbiosis has occurred several times and has resulted in extremely diverse groups of algae and other eukaryotes organisms.