Genetics Test Questions
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20100/bio%20100%20lectures/genetics-genes/mendelia.htm
Challenging Crosses (punett squares) Questions?
1. What are the expected offspring produced by a cross between a heterozygous black short-haired guinea pig and a homozygous white, long-haired guinea pig. Assume Black color (B) and short-hair (S) are dominant traits.
2. The ability to roll the tongue into almost a complete circle is conferred by a dominant trait, while its recessive allele fails to confer this ability. A man and his wife can both roll their tongues and are surprised to find that their son cannot! Explain this by showing the genotypes of all three persons.
3. In rabbits, spotted coat (S) is dominant to solid, and black (B) is dominant to brown. In a large population, brown spotted rabbits are mated to solid black ones and all the offspring are black spotted. What are the genotypes of the parents? What would be the appearance of the F2 if two of these F1 black spotted rabbits were mated?
4. In pea plants, tall plants (T) are dominant to dwarf, and yellow color (Y) is dominant to green, and smooth seed (S) is dominant to wrinkled seed. What would be the phenotypes of the following matings?
TtYySs x ttyyss
1. This can be solved using probability, but you may find it easier to draw a Punnett square. The parental genotypes are BbSs and bbss. The way I would solve this is to draw two separate Punnett squares, one for each trait (B and S). The B square will show you that half the offspring will be black and half will be white. The same is true for the S square (half long hair, half short hair). Multiply these probabilities to get your offspring ratios: 0.5 x 0.5= 0.25. There will be 0.25 with short black fur, 0.25 with long black fur, 0.25 with long white fur and 0.25 with short white fur. This is a 1:1:1:1 ratio.
2. The parents would have the genotypes Aa and Aa. The son would have the recessive genotype aa.
3.
Challenging Crosses (punett squares) Questions?
1. What are the expected offspring produced by a cross between a heterozygous black short-haired guinea pig and a homozygous white, long-haired guinea pig. Assume Black color (B) and short-hair (S) are dominant traits.
2. The ability to roll the tongue into almost a complete circle is conferred by a dominant trait, while its recessive allele fails to confer this ability. A man and his wife can both roll their tongues and are surprised to find that their son cannot! Explain this by showing the genotypes of all three persons.
3. In rabbits, spotted coat (S) is dominant to solid, and black (B) is dominant to brown. In a large population, brown spotted rabbits are mated to solid black ones and all the offspring are black spotted. What are the genotypes of the parents? What would be the appearance of the F2 if two of these F1 black spotted rabbits were mated?
4. In pea plants, tall plants (T) are dominant to dwarf, and yellow color (Y) is dominant to green, and smooth seed (S) is dominant to wrinkled seed. What would be the phenotypes of the following matings?
TtYySs x ttyyss
1. This can be solved using probability, but you may find it easier to draw a Punnett square. The parental genotypes are BbSs and bbss. The way I would solve this is to draw two separate Punnett squares, one for each trait (B and S). The B square will show you that half the offspring will be black and half will be white. The same is true for the S square (half long hair, half short hair). Multiply these probabilities to get your offspring ratios: 0.5 x 0.5= 0.25. There will be 0.25 with short black fur, 0.25 with long black fur, 0.25 with long white fur and 0.25 with short white fur. This is a 1:1:1:1 ratio.
2. The parents would have the genotypes Aa and Aa. The son would have the recessive genotype aa.
3.