Multiple Choice
In the context of the evolution of the eukaryotic cell, the best-supported explanation for how mitochondria and chloroplasts arose is which of the following?
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1. Overview of Cell Biology
Evolution of the Cell
Multiple Choice
In the context of the evolution of the cell, how did chloroplasts end up in the cells of photosynthetic producers (e.g., plants and algae)?
A
Through horizontal gene transfer alone, in which chloroplasts were assembled from imported genes without any symbiotic event
B
Through endosymbiosis, in which an ancestral eukaryotic cell engulfed a photosynthetic cyanobacterium that became a chloroplast
C
Through spontaneous de novo formation of chloroplasts from infoldings of the plasma membrane
D
Through mutation-driven conversion of mitochondria into chloroplasts within early eukaryotic cells
Verified step by step guidance1
Understand the concept of endosymbiosis, which is a key theory explaining the origin of certain organelles in eukaryotic cells, including chloroplasts.
Recognize that chloroplasts are believed to have originated from a symbiotic relationship where an ancestral eukaryotic cell engulfed a photosynthetic cyanobacterium.
Note that this engulfed cyanobacterium was not digested but instead became a permanent resident inside the host cell, evolving into the chloroplast.
Distinguish this process from other possibilities such as horizontal gene transfer alone, spontaneous formation, or mutation-driven conversion, which do not adequately explain the presence and complexity of chloroplasts.
Conclude that the endosymbiotic event allowed the host cell to gain photosynthetic capabilities, leading to the evolution of photosynthetic producers like plants and algae.
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