Question 1

Springtails like Neelus sikkimensis are classified as true insects.

Accepted Answer

Springtails belong to the class Collembola, which are hexapods but not true insects (class Insecta). They have internal mouthparts (Entognatha) and lack wings entirely.

Question 2

Neelus sikkimensis uses specialized microscopic eyes to navigate the dark underground.

Accepted Answer

The species is completely eyeless. It relies on sensory bristles rather than vision to interact with its environment.

Question 3

Micro-arthropods in the soil are pests that damage plant roots.

Accepted Answer

Collembola are generally highly beneficial detritivores that feed on decaying organic matter, fungi, and bacteria, thereby releasing vital nutrients back into the topsoil.

Question 4

Consider the following statements regarding Neelus sikkimensis, recently discovered in Sikkim: 1. It is a new species of true insect belonging to the order Hemiptera. 2. Its discovery marks the first-ever record of the genus Neelus in India. 3. It exhibits sensory adaptation by possessing highly developed compound eyes to navigate subterranean habitats. How many of the above statements are correct?

Accepted Answer

(a) Only one — Statement 1 is incorrect because Neelus sikkimensis is a Collembola (springtail), which is a micro-arthropod but not a true insect (it lacks wings and has internal mouthparts). Statement 2 is correct; it is the first record of the genus Neelus in India. Statement 3 is incorrect; the species is completely eyeless, an evolutionary adaptation to absolute darkness deep within soil and moss layers. Thus, only one statement is correct.

Question 5

Match List I (Term related to the Neelus sikkimensis discovery) with List II (Description):
List I:
A. Collembola
B. Labral chaetotaxy
C. Entognatha
D. Bio-indicator

List II:
1. A class of wingless hexapods with internal mouthparts to which springtails belong.
2. Organisms whose population status and health reflect the overall condition of their ecosystem.
3. The scientific group name for springtails, functioning as nutrient recyclers.
4. The unique arrangement of bristles on mouthparts used for taxonomic identification.

Select the correct answer using the code given below:

Accepted Answer

(a) A-3, B-4, C-1, D-2 — Collembola (A) is the specific group known as springtails (3). Labral chaetotaxy (B) refers to the distinct arrangement of mouth bristles, which was key in identifying this new species (4). Entognatha (C) is the broader class of wingless hexapods with internal mouthparts that includes Collembola (1). A bio-indicator (D) is an organism used to assess ecosystem health (2).

Question 6

Assertion (A): Neelus sikkimensis lacks eyes completely.
Reason (R): It has evolved to inhabit dark, subterranean soil and moss layers where visual organs provide no ecological advantage.
Select the correct answer from the codes given below:

Accepted Answer

(a) Both A and R are true, and R is the correct explanation of A. — Neelus sikkimensis is a micro-arthropod discovered deep in the soil and moss of high-altitude Sikkim. Living in complete darkness, the species has undergone regressive evolution, losing its eyes entirely because maintaining visual organs requires energy that provides no benefit in a lightless environment. Therefore, the reason directly explains the assertion.

Discovery of Neelus sikkimensis in Sikkim

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