Continued

1. Chapter 14 continued

2. Using genetics to prevent disease – alzheimers, aging, etc. Using genetics to prevent disease – alzheimers, aging, etc.

6. A. Dominance Has Degrees 1. Incomplete dominance: offspring show traits intermediate between two parental phenotypes. Red and white-flowers produce pink-flowered offspring. This does not support a blending theory; parental phenotypes reappear in F2 generation.

7. The F1 hybrids have an appearance somewhere in between the 2 phenotypes of the 2 parental variations. Not blending because the red and white trait can still be retrieved from the pink. The F1 hybrids have an appearance somewhere in between the 2 phenotypes of the 2 parental variations. Not blending because the red and white trait can still be retrieved from the pink.

9. A. Dominance Has Degrees 2. Codominance is a pattern of inheritance in which both alleles of a gene are expressed. A person with AB blood has both A and B antigens on their red blood cells. With codominance, both alleles produce an effective product.

10. B. A Gene That Controls Many Traits 1. Pleiotropy: a single gene exerts an effect on many aspects of an individual's phenotype. Marfan syndrome: a mutant gene is unable to code for production of a normal protein, fibrillin. Results in the inability to produce normal connective tissue.

11. C. Genes That Interact 1. More than one pair of genes may interact to produce the phenotype. 2. Epistasis: absence of expected phenotype as a result of masking expression of one gene pair by the expression of another gene pair.

14. C. Genes That Interact Albino animals inherit allelic pair (aa) preventing production of melanin, expression of eye, hair color.

15. D. Multiple Alleles 3. The ABO system of human blood type involves three alleles. 4. As a result, there are four possible phenotypes or blood types: A, B, AB, and O.

16. E. Environment Affects the Phenotype Temperature can affect the phenotypes of some plants (e. g., primroses) and animals (e. g., Siamese cats, Himalaya rabbits).

18. F. Genes That Add Up 1. Polygenic inheritance occurs when a trait is controlled by several allelic pairs at different loci. 2. Allelic pairs at different loci on a chromosome or on different chromosomes all control one trait.

21. Chapter 15

22. A. Chromosomal Theory of Inheritance Genes are located on chromosomes. Independent assortment requires that the genes reside on different chromosomes.

23. B. Sex Chromosomes Determine Gender Autosomes are nonsex chromosomes that are the same number and kind between sexes. Sex chromosomes differ in number and kind between males and females.

27. Genes on the X Chromosomes An allele for eye color on the X but not Y chromosome Heterozygous females are carriers; they do not show the trait but can pass it on. Males are never carriers but express the one allele on the X chromosome. One form of color-blindness is X-linked recessive.

29. D. Genes Are Linked 2. All alleles on a chromosome form a linkage group that stays together except when crossing over. 3. Linked alleles do not obey Mendel's laws because they tend to go into the gametes together.

31. E. Mapping the Chromosomes 1. Percentage of recombinant phenotypes measures distance between genes to map the chromosomes. 2. Linked genes indicate the distance between genes on the chromosomes.

33. 12.3. Chromosomes Undergo Mutations

34. B. Changing Chromosome Number 1. Monosomy occurs when an individual has only one of a particular type of chromosome. 2. Trisomy occurs when an individual has three of a particular type of chromosome.

35. B. Changing Chromosome Number a. Turner syndrome: monosomy where the individual has single X chromosome. b. Down syndrome is most common trisomy among humans; it involves chromosome 21.

36. Some organisms have more than 2 complete chromosome sets. The general term for this chromosomal alteration is polyploidy. Some organisms have more than 2 complete chromosome sets. The general term for this chromosomal alteration is polyploidy.

37. Poolyploidy is relatively common in the plant kingdom. Animal kingdom it is less common but there is a rodent found in Chile as polyploidy. Poolyploidy is relatively common in the plant kingdom. Animal kingdom it is less common but there is a rodent found in Chile as polyploidy.

38. C. Changing Chromosomal Structure 1. Environmental factors including radiation, chemicals, and viruses, can cause chromosomes to break; if the broken ends do not rejoin in the same pattern, this causes a change in chromosomal structure.

43. The End.