Question

examine the chart below for blood types
blood type gene has three alleles;
a, b, and o (o is recessive)

1. cross a person that is homozygous for b blood with a person that is type o

genotype:
phenotype:

1. cross a person with o blood with a person that has ab blood

genotype:
phenotype:

(chart on the right: alleles and blood type
a+a = a
a+o = a
a+b = ab
b+b = b
b+o = b
o+o = o)

Explanation:

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1. Cross: Homozygous B × Type O

Step1: Identify parent genotypes

Homozygous B: $BB$; Type O: $OO$

Step2: Set up Punnett square

	$B$	$B$
$O$	$BO$	$BO$

Step3: Determine genotype ratio

All offspring have genotype $BO$

Step4: Determine phenotype ratio

From the chart, $BO$ = blood type B
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2. Cross: Type O × Type AB

Step1: Identify parent genotypes

Type O: $OO$; Type AB: $AB$

Step2: Set up Punnett square

	$A$	$B$
$O$	$AO$	$BO$

Step3: Determine genotype ratio

$\frac{1}{2}$ $AO$, $\frac{1}{2}$ $BO$

Step4: Determine phenotype ratio

From the chart, $AO$ = blood type A; $BO$ = blood type B
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Answer:

1. Punnett Square:

	$B$	$B$
$O$	$BO$	$BO$

Genotype: 100% $BO$
Phenotype: 100% Blood Type B

1. Punnett Square:

	$A$	$B$
$O$	$AO$	$BO$

Genotype: 50% $AO$, 50% $BO$
Phenotype: 50% Blood Type A, 50% Blood Type B