Question

Study the following and choose the correct combinations: 

S. No.	Larva	Phylum	Example
I	Auricularia	Echinodermata	Mytilus
II	Glochidium	Mollusca	Unio
III	Trochophore	Arthropoda	Nereis
IV	Planula	Cnidaria	Obelia

• A. II, IV
• B. I, III
• C. I, II
• D. III, IV

Hint:

Planula → Cnidaria, Glochidium → Unio, Trochophore → Annelida/Mollusca, Auricularia → Echinodermata.

Answer 1

The Correct Option is A

Concept: Many invertebrates possess characteristic larval stages which are useful in classification and evolutionary studies.

Step 1: Examine Statement I. Auricularia is the larva of holothurians (echinoderms). Mytilus is a mollusc and does not possess auricularia larva. Hence Statement I is incorrect.

Step 2: Examine Statement II. Glochidium is the larval stage of freshwater mussels such as Unio. Hence Statement II is correct.

Step 3: Examine Statement III. Trochophore larva occurs in annelids and molluscs. Nereis is an annelid, not an arthropod. Therefore Statement III is incorrect.

Step 4: Examine Statement IV. Planula is the characteristic larva of cnidarians such as Obelia. Hence Statement IV is correct.

Step 5: Final conclusion. Correct combinations are: \[ II \text{ and } IV \] Hence option (A) is correct.