Question

The component units of the compound eye of Cockroach are called
A. Eyelets
B. Fenestrae
C. Ocelli
D. Ommatidia

Answer 1

Hint: A compound eye can be made up of several thousand similar units. Compound eyes are characteristic of several cockroaches and insects which can perceive several images of a single object. The compound eyes are situated at the anterior portion of the head.

Complete answer:
The compound eyes of many arthropods like insects, millipedes, etc, are made up of thousands of units called ommatidia. An ommatidium is a cluster of photoreceptor cells that are surrounded by support cells and pigment cells. The outer part is enveloped by a transparent cornea.
One axon bundle innervates a single ommatidium, which usually possesses 5 to 10 individual axons, that provides the brain with a picture element. The brain assimilates the signals and forms independent picture elements. The number of ommatidia in the compound eye varies based on the type and range of the insect. Cockroaches have a compound eye made up of approximately 2,000 ommatidia that are separated from each other by a pigment sheath which extends from the basement membrane of the eye to the outer transparent corneal layer.

Therefore, the correct option is D.

Note: The compound eye is named so as it’s a compound structure of many units. The counterpart of a compound eye would be the simple eye. A simple eye refers to a form of the eye where there is a single lens without a developing retina. An ocelli is the term used for a simple eye. Fenestra is any small opening or pore, commonly used as a term in the biological sciences.