Biology
Chapter 10
Name _____________________________
Period _________ Date________________
Genetics Problems
/20
Punnet squares are used to predict the traits that could appear in the offspring if you know the genotypes of the
parents, and to solve genetics problems. Use the table human inherited traits below to solve the genetics problems
below using Punnet squares.
Trait
Dominant Gene
Recessive Gene
Hair Line
Cleft Chin
Bent Little Finger
Ear Lobes
Cystic Fibrosis
Tay-Sachs Disease
Phenylketonuria
Widow’s Peak (W)
Cleft Chin (L)
Bent Little Finger (B)
Free Ear Lobes (E)
Normal (no C.F. Disease) (F)
Normal (no Tay-Sachs Disease) (T)
Normal (no PKU Disease) (P)
Straight Hairline (w)
Smooth Chin (l)
Straight Little Finger (b)
Attached Ear Lobes (e)
Cystic Fibrosis (has C.F. Disease) (f)
Tay-Sachs (has Tay-Sachs Disease) (t)
Phenylketonuria (has PKU Disease) (p)
1. If a heterozygous mother who has a widow’s peak and a homozygous father who has a straight hairline have
children, what is the likelihood that a child of theirs will have a widow’s peak?
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% WW
_____% Ww
_____% ww
c. Offspring phenotypes: _____% Widow’s Peak _____% straight hairline
2. Determine the possible genotypes and phenotypes of the offspring for a family whose mother has a smooth chin
and whose father has a cleft chin (homozygous).
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% LL
_____% Ll
c. Offspring phenotypes: _____% Cleft Chin
_____% ll
_____% Smooth Chin
3. If both the mother and father of a family are heterozygous for bent little fingers, what are the chances of them
having a child with a straight little finger?
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% BB
_____% Bb
c. Offspring phenotypes: _____% Bent finger
_____% bb
_____% Straight finger
4. Determine the possible genotypes and phenotypes of the offspring for a family whose mother and father have
attached ear lobes.
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% EE
_____% Ee
c. Offspring phenotypes: _____% Free E. L.
_____% ee
_____% Attached E. L.
5. If the mother of a family is ‘normal’ but carries the recessive gene for cystic fibrosis and the father is also normal
and does not carry the gene for cystic fibrosis, what are the chances of them having a child with a cystic fibrosis?
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% FF
_____% Ff
c. Offspring phenotypes: _____% Normal
_____% ff
_____% Cystic Fibrosis
6. Determine the possible genotypes and phenotypes of the offspring for a family whose mother and father are both
normal ‘carriers’ of Tay-Sachs disease.
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% TT
c. Offspring phenotypes: _____% Normal
_____% Tt
_____% tt
_____% Tay-Sachs
7. If the father of a family has phenylketonuria and the mother is normal and doesn’t carry the recessive gene for
PKU, what are the chances of having a child with PKU?
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% PP
c. Offspring phenotypes: _____% Normal
_____% Pp
_____% pp
_____% Phenylketonuria
8. Determine the possible genotypes and phenotypes of the offspring for a family whose mother and father are both
normal non-carrier’ of phenylketonuria.
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% PP
c. Offspring phenotypes: _____% Normal
_____% Pp
_____% pp
_____% Phenylketonuria
9. A husband and wife recently returned home from the hospital with their newborn and are starting to think that
maybe the baby is not actually their own. Neither the husband nor the wife has a widow’s peak, but their baby
does have a widow’s peak. Determine the genotypes of the mother and father and the possible genotypes and
phenotypes for any child of theirs.
a. Mother’s genotype: _________
Father’s genotype: _________
b. Offspring genotypes: _______% WW
_____% Ww
_____% ww
c. Offspring phenotypes: _____% Widow’s peak _____% Straight Hairline
d. Could this newborn be their baby? Explain ___________________________________________________
10. In a paternity suit a mother is claiming that a NBA star is the father of her child. She has attached ear lobes and
the NBA star has free ear lobes, whereas the also child has free ear lobes. Could this information be used to
prove that he is or is not the child’s father? Explain _______________________________________________
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