Ch 9 Assignment - The study of genetics can be traced back to the Greek physician

Big idea: Mendel’s Laws

Answer the following questions as you read modules 9.1–9.10:

1. The study of genetics can be traced back to the Greek physician ___________________

2. According to the blending theory of inheritance, a white rabbit crossed with a red rabbit would produce what kind of offspring?

3. Hair color is to as brunette is to .

4. Briefly explain the significance of Mendel’s technique of removing the stamen from one plant and brushing pollen from another plant on the remaining carpel.

5. Assume that a student is in the F1 generation. The children of that student would be in what generation?

6. List Mendel’s four hypotheses that he derived from his monohybrid cross experiments.

7. Assume that green eyes in humans are dominant to blue eyes. Further assume that these are the only two colors and that human eye color follows Mendel’s rules. A true-breeding green- eyed male produces offspring with a true-breeding blue-eyed female. What color eyes will the offspring have?

8. Match the following terms to their descriptions.

Column A Column B

When an allele has no noticeable effect on an organism monohybrid cross

The mating of two organisms that differ in one trait dominant

When an allele determines the appearance of an organism alleles

Having two different alleles for a gene homozygous

Having identical alleles for a gene heterozygous

An alternate form of a gene recessive

9. Briefly explain why you have two of every gene.

10. Are the two P alleles in Figure 9.4 on page 157 of your textbook the same gene? Briefly explain your answer.

11. The following cross, TtVv X TtVv, is an example of which of the following?

a. Monohybrid cross

b. Recessive alleles

c. Dihybrid cross

d. Dominant alleles

Ch 9 Assignment NAME_____________________

12. Mendel’s law of independent assortment states that allele pairs segregate independently of one another during gamete formation. What accounts for this behavior of alleles during gamete formation?

13. True or false: Mendel always got close to a 9:3:3:1 ratio for phenotypes in the F2 generation of any dihybrid cross. If false, make it a correct statement.

14. Purple flowers are dominant to white flowers in pea plants. A gardener mates a purple plant with a white plant and records the offspring as having all purple flowers. The gardener just per- formed a(n)

and determined that the purple plant’s genotype was .

15. Complete the table that compares the rule of multiplication to the rule of addition.

Rule of multiplication Rule of addition

Description

16. A geneticist at Chicago’s Brookfield Zoo is attempting to mate two gorillas. The gorillas are both heterozygous for hair color and hair length as represented by the following genotypes: CcLl X CcLl. Use the rules of probability to determine the chance of this mating producing an offspring that is ccll.

17. Briefly explain why we know that Debbie is heterozygous for widow’s peak as opposed to homozygous dominant.

18. A pedigree is frequently referred to as a “genetic family tree.” Briefly explain why this is a perfect descriptor for pedigrees.

19. A population of 100 pigs has 85 of them with curly tails and 15 with straight tails. The wild- type trait is .

20. A man with a recessive disease (the recessive phenotype) mates with a woman who is not affected with the disorder. However, two of their five children have the disorder. What do we now know about the woman’s genotype? Assume the disorder follows the rules of Mendel.

a. She has to be homozygous recessive.

b. She has to be homozygous dominant.

c. She is a carrier (heterozygous).

d. There is not enough information to answer this question.

Ch 9 Assignment NAME_____________________

21. Complete the Venn diagram that compares autosomal recessive to autosomal dominant disorders.

Autosomal recessive Autosomal dominant

22. List two methods doctors have for screening fetuses for genetic disorders.

23. Would a karyotype be useful for determining if a child has an autosomal recessive disorder like cystic fibrosis? Briefly explain your answer.

Big idea: Variations on Mendel’s laws

Answer the following questions as you read modules 9.11–9.15:

1. True or false: Incomplete dominance produces a distinct phenotype from the heterozygous genotype. If false, make it

a correct statement.

2. What is the probability that the F1 cross will produce a snapdragon with white flowers? Refer to Figure 9.11A on page 166 of your textbook.

3. The heterozygous genotype in an example of incomplete dominance has

a. its own distinct phenotype.

b. the recessive phenotype.

c. the dominant phenotype.

d. none of the above.

4. Many genes have multiple alleles that exist within a population. Briefly explain why, no matter how many alleles exist for a gene, any person has only two alleles.

5. A man has the A blood phenotype and his wife has the B blood phenotype. Their son has the O blood phenotype. Is this man the father of this child? Briefly explain your answer either way.

6. When an organism expresses both alleles equally, this is known as .

Ch 9 Assignment NAME_____________________

7. What fraction of the population has medium skin color? Refer to Figure 9.14 on page 169 of your textbook.

8. Complete the table that compares modes of inheritance that go beyond Mendel.

Incomplete Polygenic

dominance Codominance Multiple alleles Pleiotropy inheritance

How it differs

from the rules of

Mendel

Provide an

example of each

mode of

inheritance

9. Many of an organism’s phenotypes are determined by a combination of

and .

Big idea: The chromosomal basis of inheritance

Answer the following questions as you read modules 9.16–9.19:

1. The idea that the behavior of chromosomes during meiosis accounts for the patterns of inheritance is known as the .

a. law of independent assortment

b. chromosome theory of inheritance

c. law of segregation

d. monohybrid theory

2. A pea plant is homozygous recessive for both seed shape and color (rryy). Would this pea plant produce different gametes for these two characters? Briefly explain your answer either way.

3. True or false: Both of Mendel’s laws have their basis in the events of meiosis II. If false, make it a correct statement.

4. Genes that are located close to each other on the same chromosome are referred to as genes.

5. Briefly explain how Bateson’s and Punnett’s “failed” experiment led to the realization of linked genes.

6. A geneticist identifies 117 recombinant offspring out of a total of 1,359. What is the recombination frequency?

7. In Mendel’s classic dihybrid cross experiment with seed color and seed shape, what would the recombination

frequency have been in the F2 offspring? Refer to Figure 9.16 on page 171 of your textbook if you need a visual.

a. 0%

b. 25%

c. 100%

d. 18.8%

8. True or false: The closer two genes are to each other on a chromosome, the harder they will be to “unlink” during crossing over. If false, make it a correct statement.