Question

During the process of moulting, separation of the old cuticle from the hypodermis is known as

• A. Sclerotization
• B. Ecdysis
• C. Apolysis
• D. Apophyses

Hint:

Remember the correct chronological sequence of moulting:
Apolysis (separation) $\rightarrow$ Digestion/Deposition $\rightarrow$ Ecdysis (shedding) $\rightarrow$ Sclerotization (hardening).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Moulting (ecdysis) is the physiological process of shedding the old exoskeleton and growing a new, larger one, which allows insects to grow through successive stages.

Step 2: Detailed Explanation:
The process of moulting is controlled by hormones (primarily ecdysone) and involves several sequential steps:
1. Apolysis: This is the first step of moulting. Under hormonal stimulation, the epidermal (hypodermal) cells divide and secrete a fluid that causes the physical separation of the old cuticle from the hypodermis, creating an apolytial space.
Thus, apolysis is the correct term for this separation.
2. Secretion of moulting fluid: The inactive enzymes (chitinases and proteases) are secreted into the apolytial space to digest the inner endocuticle layer of the old exoskeleton.
3. Deposition of new cuticle: A new epicuticle and procuticle are secreted beneath the old cuticle.
4. Ecdysis: This is the actual physical shedding or casting off of the remains of the old cuticle (exuviae), which splits along a pre-formed ecdysial line.
5. Sclerotization: The newly secreted soft cuticle is hardened and darkened through chemical cross-linking of proteins.
6. Apophyses are internal projections of the exoskeleton for muscle attachment, not a step in moulting.
Therefore, the initial separation is known as apolysis.

Step 3: Final Answer:
The separation of the old cuticle from the hypodermis is known as Apolysis.