Equipment used to work out the field of view for a microscope

An ocular micrometer is basically a tiny ruler etched into one of the ocular lenses; it can give you a better estimate of the size of a cell, provided you calibrate it with a stage micrometer, which is a microscope slide that has a scale etched into its surface.

Depends

Explanation:

It depends if the genotypes are hetero.zygous or resessive/dominant homo.zygous. Being colorblind could be represented by a resessive genotype like, bb. if their son/daughter has Bb or bb or their son/daughter in law has a resessive trait then having a color blind grandchild maybe possible. The colorblind grandson has parents that both have at least 1 resessive trait, then the grandson could not be colorblind.