Question

which of the following descriptions is true about the partial diagram below? (aks 7e)
note: h - short hair h - no hair
?
?
a the parent genotype will be shown in all of the offspring
b the missing parent is homozygous
c this is a cross of two heterozygous parents
d there is a phenotypic ratio of 1:2:1 for offspring

Explanation:

To determine the correct answer, we analyze each option:

• Option A: The parent genotype (one parent is \(H\) and the other is missing, but offspring have \(HH\), \(Hh\), and \(hh\)). A parent with genotype \(H\) (if homozygous \(HH\)) wouldn't produce \(hh\) offspring. So A is false.
• Option B: The missing parent's genotype—from offspring, we have \(HH\), \(Hh\), \(hh\). The visible parent is \(H\) (let's say the other parent: to get \(hh\), the missing parent must contribute \(h\); to get \(HH\), the visible parent contributes \(H\), but the missing parent can't be homozygous (e.g., if missing parent was \(hh\), we couldn't get \(HH\)). So B is false.
• Option C: The cross of two heterozygous parents (\(Hh\times Hh\)) gives offspring genotypes \(HH\), \(Hh\), \(hh\) in the ratio \(1:2:1\), which matches the offspring shown (\(HH\), \(Hh\), \(hh\) are present). So this is a cross of two heterozygous parents.
• Option D: Phenotypic ratio for \(H\) (short hair) and \(h\) (no hair)—if \(H\) is dominant, phenotypes would be short hair (\(HH\), \(Hh\)) and no hair (\(hh\)), ratio \(3:1\), not \(1:2:1\). So D is false.

Answer:

C. this is a cross of two heterozygous parents