If Echinoderms Are Radially Symmetrical,why Are They Considered Primitive Relatives

question 25

Multiple Choice

If echinoderms are radially symmetrical,why are they considered primitive relatives of cnidarians?

• A) Echinoderms branched from cnidarians but are considered more advanced because they also gave rise to chordates.
• B) The echinoderm larvae are originally bilaterally symmetrical but metamorphose into a radially symmetrical adult.
• C) Radial symmetry is maintained as a primitive state by all animals in the embryonic stage and can appear anywhere.
• D) Echinoderms are the most primitive of the deuterostomes and evolution begins in each group with radial symmetry.
• E) Echinoderms have a five-sided bilateral symmetry that just appears to be radial.

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Definitions:

Prostate Gland

A gland in the male reproductive system that produces seminal fluid, which nourishes and transports sperm.

Penis

The external male genital organ involved in sexual intercourse and urination.

Glans

The sensitive bulbous structure at the distal end of the penis or clitoris.

Prepuce

The foreskin, a fold of skin covering the glans of the penis or clitoris; in males, it can be circumcised for health or cultural reasons.