Question

Given below are two statements:
Statement I : When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry.
Statement II : In phylum Echinodermata, both adults and larvae are radially symmetrical.
Choose the most appropriate answer.

• A. Statement I is incorrect but Statement II is correct
• B. Both Statement I and Statement II are correct
• C. Both Statement I and Statement II are incorrect
• D. Statement I is correct but Statement II is incorrect

Hint:

Echinoderm symmetry trick: Larva = Bilateral symmetry Adult = Radial symmetry Do not confuse both stages.

Answer 1

The Correct Option is D

Step 1: Frame the statements.
We judge two claims about symmetry and echinoderms.
Step 2: Examine Statement I.
Radial symmetry means any plane through the central axis cuts the body into similar halves, as in starfish and jellyfish. This definition is correct.
Step 3: Look at adult echinoderms.
Adult echinoderms such as starfish and sea urchins show radial symmetry.
Step 4: Look at the larvae.
Echinoderm larvae, however, are bilaterally symmetrical, not radial.
Step 5: Judge Statement II.
Statement II claims both adults and larvae are radial, but the larvae are bilateral, so Statement II is incorrect.
Step 6: Conclude.
Statement I is correct but Statement II is incorrect, which is option 4.
\[ \boxed{\text{Statement I correct, Statement II incorrect}} \]