Eye pigment in a particular strain of fly is determined by two genes. an autosomal gene that controls the color of the pigments in the eye has two alleles: a dominant allele ( r ) that results in red eyes and a recessive allele ( r ) that results in sepia eyes. a sex-linked gene that controls the expression of the colored pigments also has two alleles: a dominant allele ( t ) that allows for expression of the colored pigments and a recessive allele ( t ) that does not allow for expression of the colored pigments. individuals without a t allele have white eyes regardless of the alleles of other eye-color genes.

which of the following represents a cross between a white-eyed female and a red-eyed male?

ttxrxr×ttxry
a

ttxrxr×ttxry
b

rrxtxt×rrxty
c

rrxtxt×rrxty

RrXtXt×RrXTY is representing the cross between the white eyed female and red eyed male.

Option D

The genes that are discussed here both are completely dominant over their recessive alleles. In the autosome, the dominant R gene is responsible for red eye and recessive r gene is responsible for sepia eye. But in allosome, the dominant T gene allows the eye colour to be expressed and the recessive t gene doesn't allow eye colour to be expressed and makes it white.

As the female do have 2 X chromosomes and the female is white eyed, then both the chromosomes of female have t gene.

As the male is red eyed and have one X chromosome, so the male must have atleast one R gene in autosome to make the eye colour red and must have T gene in his X chromosome to make it appear in phenotype.

So the most possible cross that is given here is RrXtXt×RrXTY.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.