Wild type blue-eyed mary has blue flowers. two genes control the pathway that makes the blue pigment: the product of gene w turns a white precursor into magenta pigment. the product of gene m turns the magenta pigment into blue pigment. each gene has a recessive loss-of-function allele: w and m, respectively. a dihybrid (wwmm) is self-pollinated. what proportion of the offspring will be magenta?

3/8

Explanation:

Two genes are involved in the determination of flower color, W/w and M/m.

The W allele uses the white pigment as a substrate to produce the magenta pigment, and the M allele uses magenta to produce blue pigment.

The recessive alleles w and m produce a non-functional protein, so the white and magenta pigments can't be transformed into their respective products if the genotype is homozygous recessive.

Please see the first attachment for a representation of the flower color pathway.

We have different genotype possibilities:      

To analyze the offspring of a dihybrid cross, we need to do the Punnett Square (see second attachment).

The genotypes that determine the magenta color are WWmm and Wwmm.

From the Punnett Square, we can see that 3/8 individuals of the offspring will be W_mm and therefore magenta.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.