What are the genotypic and phenotypic ratios when a homozygous type A mother (AA or $I^A I^A$) is crossed with a type O father (ii or $ii$)?

Answer

Crossing a homozygous type A mother ($I^A I^A$) with a type O father ($ii$) produces offspring that are all heterozygous $I^A i$ (often written Ai). The genotypic ratio is 100% $I^A i$ (0% $I^A I^A$, 0% $ii$). The phenotypic ratio is 100% type A blood (0% type O).

Explanation

What this cross is asking

You are combining one allele from the mother with one allele from the father to predict the possible blood types of their children. Because ABO blood type follows dominance, $I^A$ is dominant over $i$.

Identify the alleles each parent can pass on

Mother is homozygous type A: $I^A I^A$
Possible gametes from mom: only $I^A$
Father is type O: $ii$
Possible gametes from dad: only $i$

Combine gametes (Punnett square idea)

Every child gets:

$I^A$ from mom
$i$ from dad

So every offspring genotype is: $$I^A i$$

Turn genotypes into phenotypes (blood types)

Since $I^A$ is dominant over $i$, the genotype $I^A i$ shows type A blood.

Final ratios

Genotypic ratio: 100% $I^A i$ (Ai)
Phenotypic ratio: 100% type A