Punnet Square-Pedigree
Short Answer
One sex-linked trait occurring on the X chromosome is color blindness (XC).
Study the pedigree below that
shows the occurrence of color blindness in three generations of a family. Use
the information below to help
answer the following questions.
X=X chromosome Y=Y chromosome C=normal vision C=color-blind trait
1.
What is the genotype of the first generation female, person 4? ____________
2.
What is the probability in percent of person 6 passing on the color-blind
trait? ______ %
3.
What is the genotype of the first generation male, person 5? __________
4.
Person 5 is color-blind. However, his sons do not have this condition. What
accounts for this?
5.
What is the probability in percent of person 7 passing on the color-blind
trait? ________ %
Skill: Observing and Inferring
Fur length is an inherited trait in guinea pigs. Short fur is dominant (F)
and long fur is recessive (f).
6.
What letters would be used to represent the genotype of these parents?
___________
7.
From your study of Mendel�s experiments, infer how two parents with short fur
could have offspring with
long fur.
8.
Describe the phenotype of these parents.
9.
Study the genetics problems below. Complete the Punnett squares by writing
the parent genotypes in the
correct place and determining the offspring genotypes. Then, describe each
phenotype.
1.
Dominant: chin cleft (C) 2. Dominant: dimples (D)
Recessive: no cleft (c) Recessive: no dimples (d)
Parents: CC � cc Parents: Dd � D
3. phenotype 1: _______________________________________
4. phenotype 2: _______________________________________
10.
Complete the Punnett square by identifying the parental genotypes in the
correct places and determining the
possible genotypes of the offspring.
Dominant gene: curly hair (H)
Recessive gene: straight hair (h)
Parents: Hh � hh
What are the genotypes and phenotypes of the offspring?
Genotypes ____________ and _____________
Phenotypes ____________ and _____________
Problem
11.
Write a pedigree for a family (parents and four children) in which one girl
and one boy are color-blind while
one boy and one girl are not.
12.
If two people are heterozygous for cystic fibrosis, what are the chances that
their children will have the
disease?
13.
Suppose you crossed a heterozygous yellow pea plant (Yy) with a homozygous
green pea plant (yy). What are
the possible genotypes and phenotypes of the offspring? Use the Punnett
square in Figure 11-1 to compute
your answers.
Figure 11-1
Possible genotypes ___________________ and ___________________
Possible phenotypes ___________________ and ___________________
14.
The pedigree shown in Figure 11-2 shows the inheritance pattern in one family
for color-blindness. How is
this disease inherited?
Figure 11-2
Multiple Choice
Identify the choice that best completes the statement or answers the
question.
____ 15.
A Punnett square shows you all the ways in which _____ can combine.
1 sperm 3 alleles
2 eggs 4 colors
____ 16.
In a Punnett square, a capital letter stands for a _____ allele.
1 dominant 3 homozygous
2 heterozygous 4 recessive
____ 17.
Of the following, which represents a homozygous recessive genotype?
1 TTT 3 Tt
2 tt 4 TT
Gr8-Ch5-PunnetSquare-Pedigree-Test2
Answer Section
SHORT ANSWER
1.
ANS:
X X
PTS: 1
2.
ANS:
0%
PTS: 1
3.
ANS:
X Y
PTS: 1
4.
ANS:
Sons inherit on the Y chromosome from their father
PTS: 1
5.
ANS:
50%
PTS: 1
6.
ANS:
Ff
PTS: 1
7.
ANS:
In Mendel�s tall and short plants, the first generation produced showed all
offspring with the dominant tall
trait, but when seeds from those plants produced offspring, some short plants
reappeared because those seeds
carried the recessive factor. Both guinea pig parents must carry the
recessive factor to have offspring showing
the recessive trait.
PTS: 1
8.
ANS:
They have short fur.
PTS: 1
9.
ANS:
3. all have chin cleft
4. 3 with dimples, 1 without
PTS: 1
10.
ANS:
Hh, curly hair; hh, straight hair
PTS: 1
PROBLEM
11.
ANS:
The pedigree should show that the father is color-blind (XcY) the mother is a
carrier (XXc), one boy and one
girl are color-blind (XcY, XcXc), one girl is a carrier (XXc), and one boy is
normal (XY).
PTS: 1 DIF: A OBJ: 8/2 STA: LE 2.2c
LOC: NYC.1.h
12.
ANS:
The chances are one in four that their children will inherit both recessive
genes and have cystic fibrosis.
PTS: 1 DIF: A OBJ: 7/2 STA: LE 2.2a
LOC: NYC.1.g
13.
ANS:
possible genotypes: Yy, yy; possible phenotypes: yellow, green
PTS: 1 DIF: A OBJ: 3/1 STA: LE 2.2c
LOC: NYC.1.h
14.
ANS:
The disease is sex-linked and inherited on the X chromosome. The mother is a
carrier; the son has the disease;
one daughter is a carrier; of the grandchildren, one girl is a carrier and
one boy has the disease.
PTS: 1 DIF: A OBJ: 8/2 STA: LE 2.2c
LOC: NYC.1.h
MULTIPLE CHOICE
15.
ANS:
STA:
16.
ANS:
STA:
17.
ANS:
3 PTS: 1 DIF: B OBJ: 3/1
LE 2.2c LOC: NYC.1.h
1 PTS: 1 DIF: B OBJ: 3/1
LE 2.2c LOC: NYC.1.h
2 PTS: 1 DIF: B OBJ: 3/1
STA: LE 2.2b LOC: NYC.1.g