The waxy secretion of the cockroach is present in both sexes. It is a soft material, freely exposed on the surface of the cuticle, which must be readily removed by contact with the surroundings

The inner layer of the gizzard of a cockroach is covered by the cuticle.

Explanation:
The gizzard is a specialized organ found in the digestive system of many animals, including cockroaches. It is responsible for grinding and breaking down food particles before they move on to the midgut for further digestion and absorption.

The gizzard is composed of several layers, including an outer layer of muscle and an inner layer that is responsible for the actual grinding of food particles. The inner layer of the gizzard is covered by a tough, protective layer called the cuticle.

The cuticle is a non-living, protective layer that covers the outer surface of many animals, including insects like cockroaches. It is composed of a protein called chitin, which provides strength and flexibility to the cuticle.

The cuticle serves multiple functions in insects, including protection against mechanical damage, prevention of water loss, and defense against pathogens. In the case of the gizzard of a cockroach, the cuticle protects the inner layer of the gizzard from the abrasive action of food particles during the grinding process.

By forming a tough barrier, the cuticle helps to prevent wear and tear on the delicate inner layer of the gizzard, allowing it to efficiently grind food particles without damage. Additionally, the cuticle also helps to maintain the structural integrity of the gizzard, ensuring its proper functioning in the digestive process.

In conclusion, the inner layer of the gizzard of a cockroach is covered by the cuticle, which serves as a protective layer against the abrasive action of food particles during the grinding process.