Placozoan Evolutionary Relationships to Other Animals Are Currently Unclear, and Different

question 38

Multiple Choice

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, though the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. The next three questions refer to the phylogenetic trees that follow.
I.
II.
III.
-Cycliophorans have two types of larvae. One type of larva-the Prometheus larva-develops into a male. The male, which lacks a digestive system, attaches to the outside of a feeding stage (a female) and impregnates her digestive system, which develops into a different type of larva. What must be true of the digestive system of the feeding-stage female while she is still a virgin?
1) At least some of its cells are haploid.
2) It consists only of highly specialized cells.
3) It is the same size as the male.

• A) 1 only
• B) 2 only
• C) 3 only
• D) 1 and 3
• E) 2 and 3

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Definitions:

Varies

To differ in size, amount, degree, or nature from something else in a group, set, or series.

Oral Reprimands

Verbal warnings or admonishments given to an employee for unsatisfactory performance or behavior.

Specific Behaviors

Particular actions or conduct exhibited by individuals in various situations, often observed to understand or predict psychological phenomena.

Appropriate

Suitable or proper in the circumstances.