A) He might be more likely heterozygous black B He might be more likely homozygous brown C) He must be heterozygous brown. D) He must be homozygous black E He must be homozygous brown 2-11 "Dumpy" is a commonly used mutant phenotype in the nematode wom C. elegans. Two "Dumpy individuals are crossed to each other and this cross produces 210 "Dumpy" and 68 wild-type individuals. If one of the "Dumpy" individuals used in this cros5 was mated with a wild-type, what ratio of "Dumpy" wild-type would we observe in the offspring? A) 0:1 B) 1:0 C) 1:1 D) 1:3 E) 3:1 2-12 If genes assort independently, a testcrossed dihybrid characteristically produces progeny phenotypes in the ratio: A) 1:1 B) 1:1:1:1 c) 1:2:1 D) 3:1 E) 9:3:3:1 2-13 A fish of genotype a/a; B/b is crossed to a fish whose genotype is 4/a; B/b. What proportion of the progeny will be heterozygous for at least one of the genes? (Assume independent assortment.) A) 1/8 B) 1/4 C) 1/2 D) 5/8 E) 3/4 2-14 In hogs, a dominant allele B results in a white belt around the body. At a separate locus the dominant allele S causes fusion of the two parts of the normallly cloven hoof resulting in a condition known as syndactyly. A belted syndactylous sow was crossed to an unbelted cloven-hoofed boar, and in the litter there were: 25% belted syndactylous 25% belted cloven 25% unbelted syndactylous 25% unbelted cloven The genotypes of the parents can best be represented as: A) B/B;S/SX bbs/s B) B/b;S/s X bb;S/S C) B/b:S/s X B/B;s/s D) b/b;S/s X B/bs/s E) B/b;S/s X b/b;s/s 2-15 In the cross between a female A/a B/b;c/cD/dele and male A/a,b/b;C/c D/d;e/e, what proportion of the progeny will be phenotypically identical to the female parent? (Assume independent assortment of all genes and complete dominance.) A) 1/16 B) 9/64 C) 3/16 D) 9/16 E) 3/8 2-16 Huntington's disease is an autosomal dominant trait. Given the pedigree below, use H to represent dominant, h to represent recessive, answer the following questions d. 1956 1960 O D d. 1988 d. 1990 14 15 13, 16 19 II d. 1972 10 11 12 (1) What is IV2's genotype? (2) What is the probability of Il being homozygous, assuming no mutation? (3) What is III15's genotype? (4) What is the probability of II15 and II16 have the same genotype? (5) What is IV9's genotype? (6) Knowing IV9 has Huntington's disease, what is the probability of IV9 being homozygous? (7) IfIV3 and IV9 have children what is the probability of havinga child without Huntington's disease?