NEET BIOLOGY

Detailed explanation-1: -Eukaryotic cells arose through endosymbiotic events that gave rise to the energy-producing organelles within the eukaryotic cells such as mitochondria and chloroplasts.

Detailed explanation-2: -The endosymbiotic theory explains how eukaryotic cells evolved. The large and small cells formed a symbiotic relationship in which both cells benefited. Some of the small cells were able to break down the large cell’s waste s for energy. They supplied energy not only to themselves but also to the large cell.

Detailed explanation-3: -The leading hypothesis, called the endosymbiotic theory, is that eukaryotes arose as a result of a fusion of Archaean cells with bacteria, where an ancient Archaean engulfed (but did not eat) an ancient, aerobic bacterial cell.

Detailed explanation-4: -Eukaryotes arose about 1.6 billion years ago, at a time when oxygen levels were still very low on Earth, both in the atmosphere and in the ocean.

Detailed explanation-5: -Mitochondria and chloroplasts likely evolved from engulfed prokaryotes that once lived as independent organisms. At some point, a eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryote, gradually developing into a mitochondrion.