Chromosomes & Inheritance
Section 12-1 Sex Determination
1. Geneticist Thomas Hunt Morgan conducted breeding experiments with what
animal?
2. How many pairs of chromosomes are found in Drosophila.
3. Are the chromosomes in male & female fruit flies the same? Explain.
4. What did Morgan name the 2 chromosomes in the non-identical pair?
5. Describe the shape of the 2 chromosomes in the non-identical pair.
6. Morgan hypothesized that the non-identical pair were the _____________
chromosomes.
7. All other chromosomes except X and Y are called
______________________________.
8. What is the genotype for males? Females?
9. When male & female fruit flies are crossed, what percent of the offspring will
be male? Female?
10. Because the X chromosome was much bigger than the Y chromosome, what did
Morgan hypothesize?
11. Genes on the X chromosome are ____________________________ genes.
12. What is meant by sex linkage?
13. Did Morgan’s experiments prove or disprove the existence of sex-linked traits?
14. Name a trait that Morgan discovered was carried on the X chromosome in fruit
flies.
15. Use a Punnett Square to show the results of crossing a red-eyed female (XRXR)
with a white-eyed male XrY.
16. Use a Punnett Square to show the results of crossing a red-eyed female (XRXr)
with a red-eyed male XRY.
17. What are linkage groups?
18. What 2 fruit fly traits did Morgan discover were linked?
19. What is the effect of crossing-over on genes?
20. Do genes that are close together or far apart get crossed over more often?
21. What is a chromosome map?
22. What scientist made a chromosome map of Drosophila?
23. How is one amp unit determined?
24. What is germ cell mutation & what is its effect?
25. What are somatic mutations, give an example, & can they be passed on to
offspring?
26. What are lethal mutations?
27. What are chromosome mutations?
28. Name & describe 4 types of chromosome mutations.
29. What are gene mutations?
30. What are point mutations?
31. What are substitutions & give an example of a disease caused by this type of
gene change?
32. What are frame shift mutations?
Section 12-2 Human Genetics
33. What is a pedigree?
34. Write the symbol that would appear on a pedigree for each of the following:
a. Male carrier?
b. Male with trait?
c. Female carrier?
d. Female with trait?
35. Name several single allele traits (both dominant & recessive).
36. Name 3 sex-linked traits.
37. What are polygenic traits and name four.
38. What influences the expression of a sex-influenced trait?
39. Name & describe 2 types of nondisjunction.
40. What causes Down syndrome?
41. When would genetic screening be useful?
42. What is amniocentesis?
43. What disease is genetically screened fro immediately after birth in the U.S.?