Choanoflagellates are single-celled eukaryotes that feed on bacteria. In the presence of their food bacteria, some choanoflagellates develop multicellular structures in which the individual choanoflagellate cells are attached to one another. Based on this observation, it may be assumed that:
A)the bacterial cells, or a chemical released by the bacteria, bind to a receptor on the plasma membrane of the choanoflagellate cells.
B)the choanoflagellate cells use cadherins to attach to each other.
C)the choanoflagellates use integrins to attach to each other.
D)choanoflagellates are complex multicellular organisms because they alternate between single cell and multicellular states.

Question

Quizplus · Accepted Answer

The observation that choanoflagellates develop multicellular structures in the presence of their food bacteria suggests that the bacteria, or a chemical released by the bacteria, triggers a response in the choanoflagellate cells that results in cell-cell attachment. It is likely that this involves binding of the bacterial molecule to a receptor on the plasma membrane of the choanoflagellate cells, initiating a signaling pathway that leads to the formation of the multicellular structures. Cadherins and integrins are proteins involved in cell-cell adhesion in animals, but they are not likely to be present in choanoflagellates. The observation does not support the idea that choanoflagellates are complex multicellular organisms that alternate between single cell and multicellular states.

Choanoflagellates Are Single-Celled Eukaryotes That Feed on Bacteria