Match the entries in column I and column II.
Which one of the following combinations is correct?
Show Hint
In matching questions, identify the most unique structure first.
The "stomochord" is a highly specific key term associated exclusively with Hemichordata, which immediately establishes S - iii and narrows down the correct choice.
Step 1 : Understanding the Question:
This question requires matching various taxonomic categories of animals in Column II with their unique morphological and anatomical features listed in Column I.
We are examining characteristics from Phylum Chordata, Class Cyclostomata, Class Chondrichthyes, and Phylum Hemichordata. Step 2. Key Formulas and Approach:
The approach involves identifying the key diagnostic features for each animal group based on standard systematic classification.
By establishing definite matches for the most distinct diagnostic features (such as the presence of a stomochord in Hemichordata), we can systematically eliminate incorrect combinations. Step 3 : Detailed Explanation:
• Notochord and hollow nerve cord present (P): These are the defining primary features of the phylum Chordata. Therefore, P matches with iv (Chordata).
• Ectoparasite with 6-15 pairs of gills and closed circulation (Q): Members of the class Cyclostomata (jawless vertebrates like lampreys) are known to be ectoparasites on certain fishes, have 6 to 15 pairs of gill slits, and possess a closed circulatory system. Therefore, Q matches with i (Cyclostomata).
• Marine animals with persistent notochord and placoid scales (R): Class Chondrichthyes (cartilaginous fishes, such as sharks) are marine organisms with a lifelong persistent notochord and skin covered by placoid scales. Therefore, R matches with ii (Chondrichthyes).
• Animals with open circulatory systems and stomochord (S): Phylum Hemichordata comprises worm-like marine animals with an open circulatory system and a rudimentary structure in the collar region called a stomochord. Therefore, S matches with iii (Hemichordata). Step 4 : Final Answer:
Combining these individual matches, we obtain: P - iv, Q - i, R - ii, S - iii.
This corresponds to Option (A).
