Question

Chapter 9 Reading Guide Big Idea: Mendel’s Laws




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 a ______________ as brunette is to a ______________. 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: monohybrid cross, dominant, recessive, alleles, homozygous, and heterozygous. a. An alternate form of a gene: ______________ b. When an allele has no noticeable effect on an organism: ______________ c. The mating of two organisms that are heterozygous for one character: ______________ d. When an allele determines the appearance of an organism: ______________ e. Having two different alleles for a gene: ______________ f. Having identical alleles for a gene: ________________
9. Briefly explain why you have two of every gene. 10. Are the two P alleles in Figure 9.4 on page 161 of your textbook the same gene? Briefly explain your answer. 11. The following cross, TtVv × TtVv, is an example of which of the following? a. Monohybrid cross b. Recessive alleles c. Dihybrid cross d. Dominant alleles 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 (meiosis)? 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 performed 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 × 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 mutant 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. 21. Complete the Venn diagram that compares autosomal recessive with autosomal dominant disorders. 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.

Answer 1

1. Hippocrates

2. Pink offspring

3. character; trait

4. He could control the mating of the plants

5. F2 generation

6. The key principles of Mendelian inheritance are summed up by Mendel's three laws: the Law of Independent Assortment, Law of Dominance, and Law of Segregation.

7. Green eyes because the green eyes are dominant to the blue eyes.

8. a. allele

b. recissive

c. monohybrid cross

d. dominant

e. hetrozygous

f . homozygous

9. We have two of every gene because they are homologous chromosomes.

10. an allele is a variant form of a gene

11. dihybrid cross

12. meosis 1

13. true

14. test cross , homozygous

15. When the number of genes increases beyond three, the number of possible phenotypes and genotypes increases exponentially, so that even the forked line method may become unwieldy. In such cases, we may have to use the rules of probability, which are briefly described in this section

19. curly tail

20. she is a carrier (hetrozygous)

rest I am not sure about the answer