BIO 102 Fall 2010

Genetics extra questions

  1. Physically, what are alleles?
  1. For each genotype, indicate whether it is heterozygous or homozygous

Aa BB KK yy Xx

  1. For each of the genotypes below, determine the phenotype. 6 finger allele (T) is dominant to 5 finger allele (t)

TTTttt

  1. The purple flower allele (F) is dominant to the white flower allele (f). A white flowered plant is crossed with a plant that is heterozygous for the trait.

Include a – d in your analysis.

  1. The genotype and phenotype of each parent
  2. The gametes that each plant makes – can show these in the Punnett square.
  3. The genotypes AND phenotypes of the possible offspring
  4. The percentage of the offspring expected to have PURPLE flowers.
  1. Yellow seed allele (Y) is dominant. Green seed allele (y) is recessive. If a heterozygous pea plant is allowed to self-pollinate, what proportion of offspring will also be heterozygous?
  1. In guinea pigs, short hair is dominant to long hair

Two short haired guinea pigs are mated several times. Out of 100 total offspring, 28 of them have long hair. What are the probable genotypes of the parents? Show the cross.

  1. A woman with type A blood has a child with type O blood. She claims that man of blood Type B is the father of her child. How would you respond to the following statements. Provide details and/or show the cross that supports your statement.
  2. The man claims: The mother's blood is type A, so the child's type O blood did not come from him
  3. The motherclaims that further testing has shown that the man is heterozygous
  1. The long fur of Persian cats is recessive to the short fur of Siamese cats (fur length gene), The black fur of Persians is dominant to the brown and tan fur of Siamese (fur color gene). Mating of a male black Persian with a female Siamese produces an f1 generation heterozygous for both of these genes.

Complete a Punnett square to show the expected genotypes and phenotypes of the offspring from the mating of these f1 heterozygous cats. Use letters that enable you to easily distinguish between the dominant and recessive alleles)

  1. In cows, the CRallele gives a red coat color, while the CW allele gives white. CR CW cows are roan - they exhibit patches of red and white, Predict the phenotypic ratios of offspring when a white cow is crossed with a roan bull.
  1. The color of fruit for a certain plant is determined by two alleles. When two plants with orange fruits are crossed, the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit, 25% yellow fruit.
  2. What are genotypes of the parent orange-fruited plants? Use letter C for color gene.
  3. What type of inheritance is occurring? (choose one)

Codominance2 gene inheritanceMultiple allelesIncomplete dominance

  1. The ability to taste PTC, a bitter substance, is a dominant autosomal (not sex-linked) trait. A man who can taste PTC has a mother who cannot taste PTC. The man’s wife cannot taste the substance. What is the chance that their child will inherit the ability to taste PTC?
  1. Specific form of a gene2. Aa 3. 6 fingers, 6 fingers, 5 fingers 4. ff X Ff, f and f = white parent F and f = purple parent offspring = 50% white ff and 50% purple Ff

5. 50% 6. Ss X Ss = heterozygous parents 7. a. mother can be AO and father BO to produce OO child, type O. b. father is BO 8. BBLL (black Persian) X bbll (brown Siamese) = F1 generation of BbLl (black Persian). Punnett square will yield 9/16 black, Persian, 3/16 black Siamese, 3/16 brown Persian, 1/16 brown Siamese 9. ¼ red ½ roan ¼ white 10. Cc incomplete dominance 11. Cross is Pp X pp = ½ chance child will taste PTC.