REVIEW answers Genetics 1 (ch 14ish)
1 A couple who are both carriers for the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will have cystic fibrosis? 25%
3 What is a genetic cross between a homozygous recessive individual and one of an unknown genotype? a test-cross
5 In snapdragons, heterozygotes have pink flowers, whereas homozygotes have either red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers? 100%
\
7 Feather color in budgies is determined by two different genes that affect the pigmentation of the outer feather and its core. Y_B_ is green; yyB_ is blue; Y_bb is yellow; and yybb is white. A green budgie is crossed to a blue budgie. Which of the following results is not possible? all green offspring -all blue offspring - all white offspring - all yellow offspring
9 A couple has three children, all of whom have brown eyes and blond hair. Both parents are homozygous for brown eyes (BB), but one is a blond (rr) and the other is a redhead (Rr). What is the probability that the next child will be a brown-eyed redhead? 1/2
Use the information below to answer the following question(s).
A woman and her husband both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait.
11 If their first two children have normal pigmentation, what is the chance that their third child will be an albino? 25%
13 Sickle-cell anemia is the result of a single recessive gene in thehomozygous state (ss), yet this disease has a complex set of symptoms affecting many parts of the body. Which term is most applicable to this example?pleiotropy
Use the information given below to answer the following question(s).
A woman who belongs to blood group A and is Rh positive has a daughter who is O positive and a son who is B negative. Rh positive is a simple dominant over Rh negative.
15 Which of the following is a possible genotype for the son? IBirr
17 Which of the following is a possible phenotype for the father? B positive
19 The fact that all seven of the garden pea traits studied by Mendel obeyed the pri seven pairs of alleles determining these traits are on the same pair of homologous chromosomes.seven pairs of alleles determining these traits behave as if they are on different chromosomes. A A sexually reproducing animal has two unlinked genes, one for head shape and one for tail length. Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? HT E Which of the following is an example of polygenic inheritance? skin pigmentation in humans
Refer to the terms shown below to answer the following question(s). Each term may be used once, more than once, or not at all.
1. incomplete dominance 2. multiple alleles 3. pleiotropy 4. epistasis 5. penetrance
21 The ability of a single gene to have multiple phenotype effects.3
23 The phenotype of the heterozygote differs from the phenotypes of both homozygotes. 1
Use the following information to answer the question(s). Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. A man and woman, both normally pigmented, have an albino child together.
25 The couple decides to have a second child. What is the probability that this child will be albino? 1/4
27 A 9:3:3:1 phenotypic ratio is characteristic of the F2 generation of a dihybrid cross
29 How many unique gametes could be produced through independent assortment by an individual with the genotype Aa Bb CC Dd EE? 8
31 Roan color in cattle is the result of absence of dominance between red and white color genes. How would one produce a herd of pure-breeding roan-colored cattle? It cannot be done.
(process of elimination...figure it out!)
33 Tallness (T) is dominant to dwarfness (t), while red flower color is due to gene (R) and white is its allele (r). The heterozygous condition results in pink (Rr) flower color. A dwarf red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals? TtRr--tall and pink
35 What does independent assortment refer to? . the random arrangement of chromosomal tetrads at metaphase I
<