Get a slate, marker and
eraser
What type of diagram shows a trait being passed from one
generation to the next?
A Pedigree
What symbol is used to indicate male on a pedigree?
What symbol is used to indicate female on a pedigree?
Show a mated male and female
Show a sister and brother
Show parents with two children (one boy and one girl).
Show the same family, but the son has a trait that neither parent
has.
Is the trait dominant or recessive?
Recessive
Use the letter A for the trait. Indicate the genotype (or possible
genotypes) or each person.
AA or Aa aa
Aa Aa
Show parents with three children. (Two boys and one girl)
Show the same family. Mom and the daughter have a trait.
Is the trait dominant or recessive?
It is impossible
to tell
This is a dominant trait. Indicate the genotype (or possible
genotypes) of each person.
Aa
Aa
aa
aa aa
This is a recessive trait. Indicate the genotype (or possible
genotypes) of each person.
aa
aa
Aa
Aa Aa
A family has a boy who cannot roll his tongue and a girl who can. Their father is able to roll his tongue, but
the mother is not. Mom’s father cannot roll his tongue, but all of the other grandparents can. Draw the
pedigree for this family.
White – Can Roll Tongue
Determine the genotype (or possible genotypes) of each person.
rr Rr
White – Can Roll Tongue
Rr rr
rr RrRR or Rr RR or Rr
At least one of these must be Rr
A litter of mice has three males and three females. One male is white, but all of the others are black. The parents and grandparents are all
black. Mom’s maternal grandfather is white. All other great-
grandparents are black. Draw the pedigree and write the genotypes
that you can determine.
A dark mouse (a dominant trait) has a grandparent who is white.
What is his genotype?
DD or Dd
A dark mouse (a dominant trait) has a grandparent who is white.
What is his genotype?
How could you determine his genotype?
Cross him with a white mouse.
THIS IS CALLED A TEST CROSS