Question

Match List I with List II
List I:
A. Labium
B. Proboscis
C. Labrum
D. Abductor
List II:
I. Second maxillae
II. Food Canal
III. Muscles
IV. Upper lip
Choose the correct answer from the options given below:

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

Hint:

To easily remember mouthpart homologies: the labrum is the upper lip, the labium is the lower lip formed by the fusion of the second maxillae, and the hypopharynx is the tongue-like structure.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Insect mouthparts are highly specialized appendages modified for feeding on various food substrates.
Understanding their evolutionary homology and functional anatomy is a fundamental concept in insect morphology.
Each mouthpart structure correlates with a specific developmental origin, functional role, or tissue type.

Step 2: Detailed Explanation:
Let us analyze each of the morphological pairs individually to establish the correct matches:
1. Labium (A): The labium forms the floor of the preoral cavity and is commonly referred to as the lower lip.
In evolutionary development, the labium is formed by the fusion of the paired appendages of the gnathal segment known as the Second maxillae (I).
Therefore, A matches with I.
2. Proboscis (B): The proboscis is an elongated, tubular feeding apparatus found in sucking insects like butterflies, moths, and true bugs.
This structure is physically modified to enclose or form the Food Canal (II) through which liquid food (such as nectar or plant sap) is sucked into the pharynx.
Therefore, B matches with II.
3. Labrum (C): The labrum is a simple, sclerotized plate situated anteriorly to the mouth.
It is suspended from the clypeus and acts as the Upper lip (IV) of the insect's mouthparts, helping to pull food into the cavity.
Therefore, C matches with IV.
4. Abductor (D): Abductors and adductors are types of somatic Muscles (III).
In insect mouthparts, the abductor muscles are responsible for pulling the mandibles outward and away from the median line, facilitating the chewing process.
Therefore, D matches with III.

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