MZOE-004 Solved Assignment January 2025 | INSECT TAXONOMY AND MORPHOLOGY | IGNOU MSCZOO

Q: Write short notes on the any two of the following:

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MZOE-004 Assignment Questions — January 2025

Q1. Explain the role of hormones involved in moulting and metamorphosis.

Key Points:

PTTH (brain hormone) stimulates prothoracic glands to release ecdysone.
Ecdysone (moulting hormone) directly initiates cuticle separation (apolysis) and shedding (ecdysis).
Juvenile Hormone (JH) maintains larval/nymphal characteristics; produced by corpora allata.
High JH + Ecdysone = Larva-to-larva (or nymph-to-nymph) moult.

Answer: Insect growth and development, including moulting and metamorphosis, are intricately controlled by a sophisticated endocrine system involving several key hormones. These hormones ensure the precise timing and nature of each developmental stage, transforming the insect from an immature form to an adult. At the forefront of this hormonal regulation are neurosecretory cells (NSCs) located in the insect brain. These cells produce Prothoracicotropic Hormone (PTTH), often referred to as the 'brain ho...

Q2. Differentiate between the following pairs of words.

(a)) Exopterygota and Endopterygota (125 words)
(b)) Hypognathous and Opisthognathous head (125 words)
(c)) Piercing-sucking and Sponging type of mouth parts (125 words)
(d)) Simple and Compound eye. (125 words)

Key Points:

Exopterygota: Incomplete metamorphosis, external wing development, nymph stage.
Endopterygota: Complete metamorphosis, internal wing development, larva, pupa, adult stages.
Hypognathous head: Mouthparts directed downwards, perpendicular to body axis.
Opisthognathous head: Mouthparts directed posteriorly, between forelegs.

Answer: Insect morphology and taxonomy classify insects based on various developmental, structural, and physiological characteristics. Understanding these distinctions is fundamental to appreciating insect diversity and adaptation. The following differentiation addresses key anatomical and developmental features, highlighting the variations that enable insects to thrive in diverse ecological niches.

Q4. Write short notes on the any two of the following:

(a)) Heteromorphosis (250 words)
(b)) Polyphenism in aphids (250 words)
(c)) Diapause (250 words)

Key Points:

Heteromorphosis (hypermetamorphosis): Larval instars exhibit markedly different morphologies for distinct ecological roles.
Triungulin/Planidium: Mobile, sclerotized first instar larva in heteromorphic insects, specialized for host-finding.
Polyphenism: Environmentally induced discrete phenotypic plasticity, where one genotype produces multiple distinct morphs.
Aphid Wing Polyphenism: High population density or poor host quality induces winged (alate) forms for dispersal.

Answer:

MZOE-004 Solved Assignment — January 2025 / July 2025

INSECT TAXONOMY AND MORPHOLOGY | IGNOU Master of Science (Zoology) Programme (MSCZOO)

MZOE-004—January 2025 / July 2025

INSECT TAXONOMY AND MORPHOLOGY

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MZOE-004 Assignment Questions — January 2025

Q1. Explain the role of hormones involved in moulting and metamorphosis.

Q2. Differentiate between the following pairs of words.

Q4. Write short notes on the any two of the following:

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