Question

One theory that explains the origin of eukaryotic cells suggests that they resulted from large

prokaryotic cells engulfing smaller prokaryotic cells. These smaller engulfed cells then
contributed to the homeostatic needs of their new hosts.
Which observation supports this theory?
A bacterium is the same size as a mitochondrion.
The endoplasmic reticulum is enclosed by a membrane.
The plasma membrane consists of a phosphate layer.
The arrangement of the parts of the cytoskeleton gives a cell its shape.

Answer 1

The observation that a bacterium is the same size as a mitochondrion supports the theory of endosymbiosis in the origin of eukaryotic cells.

Step-by-step explanation:

The observation that supports the theory is that a bacterium is the same size as a mitochondrion. Mitochondria are organelles found in eukaryotic cells and are thought to have evolved from engulfed prokaryotic cells. The fact that a bacterium and a mitochondrion are similar in size suggests that the mitochondrion could have been a small prokaryotic cell engulfed by a larger prokaryotic cell.

This theory is known as the endosymbiotic theory and is widely accepted in the field of biology. It explains how some organelles, such as mitochondria and chloroplasts, originated from ancient symbiotic relationships between different types of cells. These organelles have their own DNA and replicate independently within a eukaryotic cell.

The other options presented in the question do not directly support the theory of endosymbiosis. The endoplasmic reticulum being enclosed by a membrane is a characteristic of eukaryotic cells, but it does not provide evidence for the origin of eukaryotic cells. The composition of the plasma membrane or the arrangement of the parts of the cytoskeleton also do not directly relate to the hypothesis.

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