Download Should this dog be called Spot? Imagine this microscope drama. A

Name ________________________
Date _________________________
Should this dog be called Spot?
Imagine this microscope drama. A sperm cells from a male dog fuses with an egg cell from a female dog. Each dog’s gamete
carries 39 chromosomes. The zygote that results from the fusion of the gametes contains 78 chromosomes – one set of 39
chromosomes from each parent. One pair of the zygote’s chromosomes are shown below.
Chromosome from the female dog
L
t
H
A
Chromosome from the male dog
l
T
H
a
Each chromosome of the homologous pair contains alleles for the same traits. But one chromosome may have a dominant allele
and the other a recessive allele. Use the drawings and
the table below to answer the questions that follow.
TRAIT
DOMINANT GENE
RECESSIVE GENE
Hair Length
Short (L)
Long (l)
Hair texture
Wiry (T)
Silky (t)
Hair curliness
Curly (H)
Straight (h)
Coat pattern
Spotted (A)
Solid (a)
1. Will the new puppy have a spotted coat? __________
2. Explain your answer: ________________________________________________________________
3. Does the female dog have a spotted coat? __________
4. Explain your answer: _________________________________________________________________
5. Does the male dog have a spotted coat? ___________
6. Explain your answer: _________________________________________________________________
7. What will be the texture of the puppy’s coat? ____________________________________________
8. Will the texture of the puppy’s coat resemble that of either of its parents? __________
9. Explain your answer: _________________________________________________________________
10. Will the puppy have curly hair or will it have straight hair?_________________________________
11. Does the female dog have curly hair? __________
12. Does the male dog have curly hair? __________
13. Define the term heterozygous ________________________________________________________
14. For which traits is the puppy heterozygous? ____________________________________________
15, Define the term homozygous. ________________________________________________________
16. For which traits is the puppy homozygous? ____________________________________________
17. Explain why you cannot completely describe the puppy’s parents even though you can accurately describe the puppy.
_____________________________________________________________________________________________________________
_____________________________________________________________________________________________________________
More Punnett Practice
18. In dogs long hair is dominant over short hair. A hybrid dog mates with a female dog with short hair.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
19. In fruit flies, having wings is dominant to lacking wings. A wingless fruit fly mates with a purebred winged male. Complete a
Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
20. In pea plants, purple flowers are dominant to white flowers. A heterozygous plant is allowed to self pollinate. Complete a
Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
21. In humans having dimples is dominant to having no dimples. Cross a heterozygous dad to a purebred mom with dimples.
Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
22. In humans, having six fingers is a dominant trait to having five fingers. Two people who have six fingers met and had children.
Assume that both are heterozygous for the trait, since they each had a parent who had five fingers. They wanted to know the
odds of having children with six fingers. Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
23. In sheep, black wool is recessive to the dominant wool color which is white. Cross a hybrid ewe (female) to a purebred male
with white wool. Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
24. In guinea pigs, a rough coat is dominant to a smooth coat of fur. One homozygous dominant male is mated to one homozygous
smooth female. Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
phenotypic ratio: _________________
25. In humans, having a widow’s peak is dominant to a straight hairline. Cross a heterozygous mom with a homozygous recessive
dad. Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________
26. In fruit flies a gray body is dominant to black bodies. Cross a hybrid male fruit fly with a homozygous dominant female fruit fly.
Complete a Punnett Square showing the possible outcomes.
Parent genotypes: ________ X ________
F1 genotypic ratio: __________________
F1 phenotypic ratio: _________________