Question

The two valves of a brachiopod shell are:

• A. Equal in size with equilateral symmetry
• B. Equal in size with inequilateral symmetry
• C. Unequal in size with equilateral symmetry
• D. Unequal in size with inequilateral symmetry

Hint:

Brachiopods have unequal valves, but each valve is bilaterally symmetrical.

Answer 1

The Correct Option is C

Concept:
Brachiopods are marine invertebrates having two shells or valves, but their shell symmetry differs from pelecypods.

Step 1: Valve size.
In brachiopods, the two valves are generally unequal in size. \[ \text{Pedicle valve}\neq \text{brachial valve} \]

Step 2: Symmetry.
Each valve is bilaterally symmetrical about a median plane, giving equilateral symmetry.

Step 3: Final answer.
Thus, brachiopod valves are unequal in size with equilateral symmetry. \[ \therefore \text{Correct Answer is (C)} \]