According to the endosymbiotic theory, why was it adaptive for the larger (host) cell to keep the engulfed cell alive, rather than digesting it as food?
A) The engulfed cell provided the host cell with adenosine triphosphate (ATP).
B) The engulfed cell provided the host cell with carbon dioxide.
C) The engulfed cell allowed the host cell to metabolize glucose.
D) The host cell was able to survive anaerobic conditions with the engulfed cell alive.
E) The host cell would have been poisoned if it had digested the engulfed cell.

Question

Quizplus · Accepted Answer

The engulfed cell, which is thought to have been a precursor to modern mitochondria (and in the case of photosynthetic cells, chloroplasts), provided the host cell with ATP, a vital energy source. This mutual benefit is a key aspect of the endosymbiotic theory, explaining how eukaryotic cells might have evolved to contain organelles like mitochondria and chloroplasts.

According to the Endosymbiotic Theory, Why Was It Adaptive for the Larger