bio question?

Question

its about genetics

please help me this is for my AP bio
orange dragon are dominant over green dragons. you have an orange one and need to know wheter it homozygous or heterozygous. If you had an unlimited amount of dragons whose genotype you absolutely knew and could make any kind of cross breeding you wish how would you breed your pet orange male dragon to determine with absolute certainty his genotype.

Answer 1

If you bred him to repeated green dragons and got EVEN ONE orange dragon, you'd know he was heterozygous for orange, because if he's homozygous, he'd never have green offspring with a green dragon, ever.

If we call the color gene O, then OO is orange, Oo is Orange and oo is green.
Oo=heterzygous
OO=homozygous for the dominant
oo= Heterozygous for the recessive.
If we made a punnet square:
(ignore the #s, they are spacers):

If your orange is OO, bred to an oo:
###|__O_|__O_
_o_|_Oo_|_Oo_
_o_|_Oo_|_Oo_
See, 100% are Oo, and therefore ALL ORANGE.

If your orange is Oo, bred to an oo:
###|__O_|__o_
_o_|_Oo_|_oo_
_o_|_Oo_|_oo_
See, 50% are Oo, and orange, and 50% are oo, and green.
If you bred the dragon repeatedly, and ALWAYS got orange, then he's probably not an Oo.

Answer 2

Do a test cross(The crossing of an organism, with an unkown genotype, to a homozygous recessive organism (tester). A cross between an individual of unknown genotype or a heterozygote (or a multiple heterozygote) to a homozygous recessive individual. ).

Cross your orange with a green and look at the ratios of offspring to determine whether the orange is homozygous or heterozygous. If the offspring are 100% orange, then your orange dragon is homozygous, if the offspring ratio is 1/2 orange and 1/2 green then your test orange dragon is heterozygous.

Answer 3

Breed it with a homozygous green female. If any green dragons are produced, then they have two green genes, and you can be certain that your dragon is a heterozygote, as it has clearly contibuted a green gene. However, you can never be 100% certain that it is a homozygote orange, using any combination of breeding pairs. Whether you breed with heterozygous or homozygous orange females, you can never be certain that the orange gene is being contributed from a heterozygote or homozygote dragon. The absence of any green dragon offspring, particularly if there are a lot of them, would suggest your dragon is homozygous, but you could never be 100% certain of homozygosity. It could be a heterozygote, who, improbably, has contributed his orange gene 100% of the time.