SAT Subject Biology Practice Question 113: Answer and Explanation
3. An organism that demonstrates radial symmetry and an exoskeleton would be classified into which phylum?
Correct Answer: C
The phyla Mollusca and Arthropoda do not exhibit radial symmetry; they are bilaterally symmetrical. Phylum Porifera demonstrates an asymmetrical body plan. Phylum Cnidaria does exhibit radial symmetry; however, this group lacks any skeletal form, leaving the only possible correct answer to be Echinodermata.