I have to demonstrate a cross between a woman with normal vision whose father was colorblind?

Do you mean like a punnett square?

If the woman has color vision but her father was colorblind, chances are she is carrying the recessive colorblind gene. Color blindness is a sex-linked trait located on the X chromosome. Because women have XX chromosomes and males have XY, the woman has two chances at having color vision; if she receives one color blind gene, the other normal X will mask it. If a male receives one colorblind gene, he has no other X to mask it, so he will be color blind.

If "C" represents color vision and "c" represents color blindness, her genotype would be Cc and her father's would be c (this is because she has XX chromosomes and he has XY, so he only has one vision gene). The punnett square would look like this:

I drew this and I hope it helps! http://img11.imageshack.us/img11/6003/punett1.png

So, the woman would be XX because that's the woman's chromosomes. The man's chromosomes are XY. The woman is normal, so those would be XX. The man is colorblind, so his chromosomes would be XY', Y' being the allele that carries the colorblindness. You'd put the woman's on the top of a Punnett square, and the man's on the left side, the X on top.of the Y', then you'd take the letter beside each square are put them into the box. For example, the woman's left and the man's top chromosome would go into the top left box, and the woman's right and the man's top chromosome would go intobthe top right and so on.

jj