Question

multiple choice question
the taxonomic level of superphylum was proposed because ______.

thousands of gene sequences cannot be affiliated with any previously defined taxa

the number of phyla in each domain exceeded a reasonable number for data management

unculturable bacteria known only by sequence data need a single catch - all taxonomic level

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Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Gene sequences not affiliating with previous taxa doesn't directly relate to the need for a superphylum.
• Option 2: When the number of phyla in a domain becomes too large for manageable data handling, a higher taxonomic level (superphylum) is proposed to organize them. This makes sense for taxonomic classification and data management.
• Option 3: A "catch - all" level isn't the purpose of superphylum; it's about organizing existing phyla, not just for unculturable bacteria.

Answer:

B. the number of phyla in each domain exceeded a reasonable number for data management