Question

Match List I with List II
List I:
A. Placoid sensilla
B. Basiconic sensilla
C. Coeloconic sensilla
D. Ampullaceous sensilla
List II:
I. Shallow pits
II. Hairless
III. Deep pits
IV. Peg like process
Choose the correct answer from the options given below:

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

Hint:

To remember sensilla morphology: placoid are plate-like (hairless), basiconic are peg-like, coeloconic are sunk in shallow pits, and ampullaceous are sunk in deep, flask-like pits.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Sensilla are specialized cuticular structures that house sensory receptor cells.
They are classified based on their external morphology and structural adaptations for detecting mechanical, chemical, thermal, or hygro-receptive stimuli.

Step 2: Detailed Explanation:
Let us match each sensillum type with its morphological characteristics:
1. Placoid sensilla (A): These are plate-like olfactory receptors (sensilla placodea) that form flat, circular, plate-like structures on the antennal cuticle.
Because they lack any hair-like projections, they are described as hairless (II).
They are commonly found on the antennae of honey bees and scarab beetles.
Therefore, A matches with II.
2. Basiconic sensilla (B): These are thick, blunt, cone-shaped projections (sensilla basiconica) that function primarily as olfactory receptors.
They project above the cuticular surface as a peg-like process (IV).
Therefore, B matches with IV.
3. Coeloconic sensilla (C): These are sensory pegs (sensilla coeloconica) that do not project above the surface, but are sunk into shallow pits (I) within the cuticle.
They typically function as chemo-receptors or hygro-receptors.
Therefore, C matches with I.
4. Ampullaceous sensilla (D): These are sensory pegs (sensilla ampullacea) that are sunk deep into the cuticle, opening to the surface via a narrow canal or deep pits (III).
They are often specialized for thermo-reception or carbon dioxide detection.
Therefore, D matches with III.

Step 3: Final Answer:
Combining these morphological descriptions yields the sequence: A-II, B-IV, C-I, D-III.