Chitin is absent in which part of the cockroach____________?
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Answer: A. Epicuticle
Explanation
The epicuticle of insects is a thin waxy outer layer that lacks chitin completely. Proteins and lipids make up this outermost layer to prevent rapid desiccation and water loss. Chitin is strictly reserved for the underlying procuticle layers which provide mechanical body strength. Insect exoskeletons feature multiple distinct layers including the epicuticle exocuticle and endocuticle. Chitin is a tough nitrogen-containing polysaccharide polymer composed of repeating N-acetylglucosamine units. The absence of chitin in the epicuticle makes it a smooth waterproof barrier.
Understanding insect cuticle composition helps researchers develop targeted pesticides that disrupt molting. Water conservation in terrestrial arthropods depends entirely on the protective properties of the epicuticle. Entomologists study these structural layers to comprehend how insects survive in extreme arid environments. The exocuticle is heavily sclerotized and contains significant amounts of chitin cross-linked with proteins. The endocuticle forms the flexible inner portion of the procuticle and contains abundant chitin fibers. Saying all of these is incorrect because the epicuticle specifically lacks the polysaccharide chitin entirely.
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