Question

In almost all vertebrates when the optic cup fails to develop in the embryo the lens also fails to form the constitutes evidence that

Answer 1

The optic cup is responsible for the formation of lens.

Step-by-step explanation:

The process of formation of vertebrate optic cup begins when optic vesicle comes in contact with ectoderm. The developing brain side bulge give rise to optic cup. The surface ectoderm is responsible for lens formation. Thus, when the optic cup fails to develop in the embryo the lens also fails to form in the development of embryo.

Answer 2

The vertebrate optic cup is a morphogenetic process which initiates after the optic vesicle starts contacting the overlying surface ectoderm.

Optic cup is usually developed from a bulge on the side of the developing brain which influences the overlying ectoderm to produce the lens.
Therefore,
When the optic cup fails to develop in the embryo, the lens also fails to form in the embryo, because cells may induce neighboring cells to differentiate.