NAME: _________________________________________________________
DATE: __________________ BLOCK: __________
LAWS OF INHERITANCE
Identify each law of inheritance.
1. The law of _________________________________ occurs when a pair of alleles is separated during the formation
of gametes.
2. The law of _________________________________ states that one allele can mask or cover up another allele of the
gene.
3. A child’s hair color has no effect on the child’s chance of inheriting a widow-peak. This is an example of
the law of _______________________________________________.
MONOHYBRID CROSS PRACTICE
4. In pea plants tall plants are dominant to short plants. Write the genotype for each of the following
phenotypes.
Homozygous Tall ___________
Heterozygous Tall_________
Short ___________
5. In humans tongue rolling (R) is dominant to non-tongue rolling (r). What would be the expected
offspring if a homozygous tongue roller was crossed with a heterozygous tongue roller? Complete a
Punnett Square
What are the genotypes of each parent
___________________ and ________________
What is the percent of the expected genotypes?
RR ___________
Rr ___________
rr ___________
What is the percent of the expected phenotypes?
Tongue roller ___________ Non-tongue roller ___________
6. In pea plants purple flowers ( _____ ) is dominant to white flowers ( ____ ). A white flowered plant is
crossed with a homozygous dominant flower. Predict the ratio of purple flowered to white flowered
offspring.
What is the genotype of the white flower? ___________
What is the genotype of the homozygous dominant flower? ___________
What is the predicted number of each genotype?
PP __________
Pp __________
pp _____________
What is the predicted number of each genotype?
Purple _______________
White _____________
What is the expected ratio of purple to white flowers? ___________
7. Complete the cross below to find the genotype of each parent.
What are the genotypes of the parents?
Tt
__________________ and _______________
tt
Tt
What is the phenotype of the parents?
_________________________________
tt
8. In goats, a recessive gene causes goats to “faint” when they are startled. A farmer breeds two goats that
have never fainted and their first offspring faints two days after its birth. What must the parents’
genotypes have been? Show the monohybrid cross to prove it.
What allele represents the normal (non-fainting goats)?
F or f
What allele represents the fainting goats?
F or f
What is the genotype of the fainting baby goat?
FF or Ff or ff
Complete the cross to the right to find out the genotype of the parent goats?
Remember both parents do not faint.
ff
What is the genotype of each parent goat? __________ and _________
DIHYBRID CROSS PRACTICE
In guinea pigs fur color and fur length are inherited together. Black fur (B) is dominant to white fur (b) and
long fur (L) is dominant to short fur (l). Predict the offspring if a homozygous black fur, long fur guinea pig
(BBLL) mated with a heterozygous black fur, short fur guinea pig (Bbll).
Fill in the Chart below
BL
BL
BL
Bl
Bl
bl
bl
Complete the following ratio
Black, Long
:
Black short
:
White, Long :
White, Short
_____________
:
_____________
:
______________ :
______________
BL