Why are Protists and Bacteria Grouped into Different Domains

Question

Why are protists and bacteria grouped into different domains?
A)Because protists eat bacteria.
B)Because bacteria are not made of cells.
C)Because protists have a membrane-bounded nucleus, which bacterial cells lack.
D)Because bacteria decompose protists.
E)Because protists are photosynthetic.

Accepted Answer

Protists have a membrane-bounded nucleus, which bacterial cells lack. This is the primary characteristic used to differentiate the domains of bacteria and eukaryotes (which include protists, plants, fungi, and animals).

Answer: A, D, E are incorrect.
 A, D, and E are not valid reasons for grouping protists and bacteria into different domains. Protists may eat bacteria, but this does not explain their taxonomic classification. Bacteria are certainly made of cells, so this is not a valid basis for grouping them separately from protists. Finally, not all protists are photosynthetic, so this also cannot be a justification for grouping them separately from bacteria.