Question

In insects feeding on nectar, the proboscis is formed by the modification of
A.Hypopharynx
B.Mandibles
C.Labium
D.Galea

Answer 1

The proboscis is an elongated feeding tube, used by non-chewing insects to take up food. This primarily involves a sucking action wherein they suck food (nectar) through the proboscis. The proboscis is a modification of the maxilla, present in all insects. Here a pair of galea of the maxilla elongate to what we know as the proboscis.
Complete step by step answer:
The proboscis is a long feeding tube, present in piercing and sucking insects, which help them pierce and suck internal fluids of foods. The proboscis is also found in siphoning insects, where the insects siphon food from surfaces.
The proboscis is a modification of the galea of the maxilla. The maxilla consists of two-parts, the proximal cardo, and the distal stripes. The distal stipes consist of two lobes of galea. As all Lepidoptera species lack mandibles, as they have evolved the galea of the maxilla to become long feeding tubes.
The two lobes of galea elongate are held together by hooks. Other insect mouthparts enable a sucking action coordinated by sacs within the head, enabling the insect to suck food through the proboscis. In the case of the Lepidoptera species, the proboscis can be curved when not in use.
Therefore, the correct option is D. Galea

Note:
The proboscis is a long tube, seen in the case of insects such as Lepidoptera.
They mainly function as tubular suction pipes to suck food materials.
The proboscis is a modification of the maxilla found in many insects.
The proboscis in nectar-consuming insects are made from a pair of galea which elongate and are held together by hooks.
Mandibles are pincher like structures seen in chewing insects used to cut and break food pieces. Nectar consuming insects are devoid of such mandibles
The hypopharynx is a globular structure mostly related to the production of saliva and swallowing of food
The labium along with maxillae is responsible for the mastication of food, in the case of chewing insects. In other insects, the labium acts as a flap or covering.