Name __________________________
Date _____________ Period _______
Expected and Observed Results
1. Mendel made the following crosses with pea plants. For the pea plants round seeds (R)
are dominant over wrinkled seeds (r). Complete the Punnett squares and answer the
questions about each cross.
a.
R
R
b.
R
R
c.
R
r
d.
r
R
R
r
r
r
r
r
R
r
2. He crossed a round pea (R) plant with a wrinkled pea (r) plant. His results were 126
round peas and 122 wrinkled peas. Which of the Punnett squares above best shows the
parents and offspring that could give these results? ______
3. He crossed a round pea plant with a wrinkled pea plant. His results were 30 round pea
plants and 0 wrinkled pea plants. Which of the Punnett squares above best shows the
parents and offspring that could give these results? ______
4. He crossed a round pea plant with a round pea plant. His results were 306 round pea
plants and 110 wrinkled pea plants. Which of the Punnett squares above best shows the
parents and offspring that could give these results? ______
5. He crossed a round pea plant with a round pea plant. His results were 300 round pea
plants and 0 wrinkled pea plants. Which of the Punnett squares above best shows the
parents and offspring that could give these results? ______
6. In corn plants, normal height (H) is dominant over short height (h). Complete these four
Punnett squares showing different crosses. Then, shade red all the homozygous dominant
offspring. Shade green all the heterozygous offspring. Leave all the homozygous
recessive offspring unshaded.
H
H
H
h
H
h
H
h
H
H
h
h
H
h
h
h
7. In flies, long wings (L) is dominant over short wings (l). Complete these four Punnett
squares showing different crosses. Then, shade red all of the offspring with long wings.
Leave all the short wing offspring unshaded.
L
L
L
l
l
l
L
l
L
L
l
l
l
l
l
l
8. In guinea pigs, short hair (S) is dominant over long hair (s). Complete the following
Punnett squares according to the directions given. Then, fill in the blanks beside each
Punnett square with the correct number.
a. One guinea pig is Ss and one is ss.
Offspring expected (number)
_______ short hair
_______ long hair
b. One guinea pig is Ss and one is SS.
Offspring expected (number)
_______ short hair
_______ long hair
c. Both guinea pigs are heterozygous for short hair.
Offspring expected (number)
_______ short hair
_______ long hair
d. One guinea pig is homozygous recessive and the other is heterozygous.
Offspring expected (number)
_______ short hair
_______ long hair
9. Examine the diagrams below. Each is a step in the Punnett square method. Put the steps
in order by writing the numbers 1 to 4 in the correct blank below the Punnett squares.
D
d
D
d
D
d
D
D
DD
D
DD
Dd
d
d
Dd
d
Dd
dd
_______
_______
_______
_______
10. What do the letters outside the Punnett square stand for? __________________________
________________________________________________________________________
What do the letters inside each box stand for? __________________________________
________________________________________________________________________
11. Examine the following Punnett squares and circle the ones that are correct.
D
d
d
Dd
dd
d
Dd
dd
A
a
A
AA
Aa
a
Aa
aa
D
D
d
Dd
DD
d
Dd
Dd
A
a
A
AA
aa
a
Aa
Aa
D
d
D
DD
Dd
d
Dd
Dd
A
a
a
Aa
aa
a
Aa
aa
D
D
D
DD
DD
d
Dd
dd
A
a
A
AA
AA
A
AA
Aa
S
S
12. Complete the following to determine the expected offspring.
T
t
e
e
R
r
T
E
R
S
T
e
r
s