Download Discussion Guide Chapter 12

Discussion Guide Chapter 11
Mader, 10th edition
1. Explain why Mendel’s experiments were successful and how the garden pea
helped him.
2. What were Mendel's conclusions that led to his Law of Segregation?
3. What is the significance of using upper- and lowercase versions of the same
letter (for example, A and a) for the dominant and recessive trait, respectively,
rather than a capital A for dominant and the letter B (or b) for recessive?
4. An individual who has two of the same alleles is said to be _______________. If
the individual has two different alleles they are said to be ______________.
5. The appearance resulting from a given gene combination is referred to as
_____________.
6. In humans the allele for albinism is recessive to the allele for normal skin
pigmentation. If two heterozygotes have children, what is the chance that a child
will have normal skin pigment? What is the chance that a child will be albino? If
the child is normal, what is the chance that it is a carrier for the albino gene?
7. How Mendel’s second law be explained with your knowledge of meiosis? (see p.
195 as well)
8. What is the significance of Mendel’s use of mathematical and statistical analysis
in his research?
9. In fruit flies, L= long wings and l=short wings; G= gray body and g = black body.
a. List all the possible gametes for a heterozygote of both traits.
b. Predict the phenotypic ratio for a cross of two individual who are heterozygote
for both traits.
10. In humans, curly hair is dominant over straight hair. A woman heterozygous for
hair curl marries a man with straight hair and they have children.
a. What is the genotype of the mother?
b. What gametes can she produce?
c. What is the genotype of the father?
d. What gametes can he produce?
e. What is the probability that their 1st child will have curly hair?
f. What is the probability that the 2nd child will have curly hair?
11. How is a test cross performed? How is it interpreted?
12. Using the key from #9, what are the most likely genotypes of the parents if a
student gets the following phenotypic results?
a. 1:1:1:1
b. 9:3:3:1
13. How might you distinguish an autosomal dominant trait from an autosomal
recessive trait when viewing a pedigree?
14. For autosomal recessive disorders, what are the chances of two carriers having an
affected child?
15. For most autosomal dominant disorders, what are the chances of a heterozygote
and normal individual having an affected child?
16. Explain inheritance by multiple alleles.
17. Not all alleles are fully _____________ or ______________. Sometimes there is
an ________________ phenotype between those of the parent, which is called
______________ ___________________. When there is a representative of both
parents phenotypes it is called ___________________.
18. What is the subtle difference between incomplete dominance and
codominance?
19. In radishes, the gene that controls color exhibits incomplete dominance. Purebreeding whit radishes make purple radishes. What are the genotypic and
phenotypic ratios when you cross a purple radish with a white radish?
20. In the 1950’s, a young woman sued film star/director Charlie Chaplin for parental
support of her illegitimate child. Charlie Chaplin’s blood type was already on
record as type AB. The mother of the child had type A and her son had type O
blood. Complete a Punnett square for the possible cross of Charlie and the
mother.
a. The judge ruled in favor of the mother and ordered Charlie Chaplin to pay
child supportcosts of the child. Was the judge correct in his decision based on
blood typing evidence? Explain why or why not. *refer to any Punnett
squares to support your answer.
21. Why are the traits of (a) human skin color and (b) human height not suitable
for explaining the concept of simple dominance?
22. Explain how multifactorial traits are related to polygenic traits.
23. In Morgan’s experiment he found that female fruit flies could have white eyes.
How could that happen if the trait is sex linked? (Hint: A Punnett square may
help).
24. Why do sex linked traits occur more often in males than females?
25. List the possible genotypes of the following hemophilia pedigree chart below.
Remember hemophilia is a sex linked trait that is caused by a recessive allele,
therefore you must denote the individuals’ sex chromosomes (XNXn and XnY) as
well as the hemophilia allele (n).