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Worksheets104 Choanoflagellates
Total questions: 11
Worksheet time: 6mins
Animals are thought to be most closely related to which group of protozoans?
choanoflagellates.
charophytes.
chytrids.
fungi.
Which cell type in sponges has a collar of cilia to filter food particles and a flagellum that creates a water current?
amoebocyte
ostiocyte
pinacocyte
choanocyte
What type of genes are needed going from being single-celled to being multi-cellular?
genes for cells to adhere (stick) to each other
genes to make a blastula
genes for cells to communicate with each other
genes for cells to secrete a non-living extra-cellular matrix
genes for cell specialization
What is the key significance of the choanocyte cell for animal evolution?
The key significance is that it is an interesting way to feed that sponges use.
The key significane is that it is an interesting way that choanoflagellates feed.
The key significance is that both the choanoflagellate protozoans and sponges have the same identical cell type indicating a close evolutionary relationship.
The choanocyte cell is interesting in the way it exapted the cilia and flagella, but beyond that it does not have much evolutionary significance.
What is the relationship between choanoflagellates and all other animals?
They have an evolutionary synapomorphy.
They are both on the cladogram.
They are monophyletic groups.
The two are sister groups that share a common ancestor.
Why is it significant that the choanoflagellates are colonial?
Being colonial is a key transition step between being single-celled and being multi-cellular.
Colonial organisms need the same things that multicellular organisms need such as a way to organize the colony, a way for cells to stick to each other and a way for the cells to be able to communicate or signal each other.
It is interesting but not significant that choanoflagellates are colonial.
What is the supporting evidence that the choanoflagellates are the sister group to animals and thus the closest protozoan relative to the animals?
Choanoflagellates and animals share genes important for cells to adhere to each other and important for cell to cell signalling.
Choanoflagellates have some of the same Hox genes for organizing their colonies as animals have for organizing their bodies in development.
Both choanoflagellates and sponges (= the oldest lineage of animals) have the identical choanocyte-type cell.
Choanoflagellates and animals share genes important for cells to secrete a collagen-based extracellular, non-living matrix
What are key points that differentiates colonial and multicellular organisms?
In a colony, the cells can be genetically unique; in a multi-celllular organism the cells are genetically identical.
The cells in a colony can live in the colony or they can live on their own. The cells of multicellular organisms can not live on their own.
In a colony, the cells are genetically identical; in a multi-celllular organism the cells are genetically unique.
The cells in a colony can not live in their own. The cells of multicellular organisms can split up and live on their own.
What is a key advantage to living in a colony or being multicellular?
Both colonies and multicellular organismal organization have the advantage of cells not having to be lonely.
Both colonies and multicellular organismal organization have the advantage of shared labor.
Both colonies and multicellular organismal organization have the advantage of being bigger and harder to hide away from predators.
Both colonies and multicellular organismal organization have the advantage of being bigger and taking up more space in the world.
Why would colonies and multicellular organisms need proteins for adhering (sticking) together?
Without a way to stick together, the cells would have a hard time staying together.
It would take a lot of energy if cells had to constantly move in order to keep up with the other cells of a colony or the multicellular organism.
It would be impossible to maintain an optimal organization that would help the colony or multicellular organism to survive.
Why would colonies or multicellular organisms need a way for cells to signal to each other?
Without communication, it would be difficult to divide up the labor of making a living as cells would have no idea what other cells are doing.
Communication makes everything more difficult and literally invites conflict. Communication is not something colonies or multicellular organisms need but that they got stuck with from an evolutionary hangover.
