Review of Terminology

1. Review of Terminology phenotype genotype homozygous pure line heterozygous hybrid dominant recessive

2. Terminology, continued P F1 F2 Testcross Backcross

3. What are the possible genotypes? Practice Questions 2.12. Several black guinea pigs of the same genotype were mated and produced 29 black and 9 white offspring. What would you predict the genotypes of the parents to be?

4.  This is an easy one. 2.13. If a black female guinea pig is testcrossed and produces at least one white offspring, determine (a) the genotype and phenotype of the sire (male parent) that produced the white offspring, (b) the genotype of this female.

5. 2.14. Heterozygous black (Bb) guinea pigs are mated to homozygous recessive (bb) whites. Predict the genotypic and phenotypic ratios expected from backcrossing the black F1 progeny to (a) the black parent, (b) to white parent.

6. 2.17. Short hair is due to a dominant gene L in rabbits, and long hair to its recessive allele l. A cross between a short-haired female and a long-haired male produced a litter of 1 long-haired and 7 short-haired bunnies. (a) What are the genotypes of the parents? (b) What phenotypic ratio was expected in the offspring generation? (c) How many of the 8 bunnies were expected to be long-haired?

7. 2.19. Black wool of sheep is due to a recessive allele b and white wool to its dominant allele B. A white buck (male) is crossed to a white ewe (female), both animals carry the allele for black. They produce a white buck lamb that is then backcrossed to the female parent. What is the probability of a backcross offspring being black?

8. 2.22. Consider a cross between two heterozygous black guinea pigs (Bb). In how many ways can 3 black and 2 white offspring be produced? (b) What is the probability from such a cross of 3 black and 2 white offspring appearing in any order?