Biol Monohybrid Cross Worksheet

Monohybrid Cross Worksheet Name _______________________ Period ______ Part A: Vocabulary Match the definitions on the left with the terms on the right. ____ 1. genotypes made of the same alleles A. alleles ____ 2. different forms of genes for a single trait B. dominant ____ 3. gene that is always expressed C. heterozygous ____ 4. gene that is expressed only in the homozygous state D. homozygous ____ 5. genotypes made of two different alleles E. recessive Below each of the following words are choices. Circle the choices that are examples of each of those words. 6. Dominant allele D e k L N n R S d F G r k P mm uu Rr TT Oo qq Uu ww 7. Recessive allele M n 8. Homozygous dominant AA Gg KK 9. Homozygous recessive ee Ff HH 10. Genotypes in which dominant gene must show AA Dd EE ff Jj RR Ss 11. Genotypes in which recessive gene must show aa Gg Ff KK rr Oo Tt Part B: Punnett Squares 12. Examine the following Punnett squares and circle those that are correct. D d D D A a A a d Dd dd d Dd DD A AA aa a Aa aa d Dd dd d Dd Dd a Aa Aa a Aa aa 1 13. What do the letters on the outside of the Punnett square stand for? ______________________ ___________________________________________________________________________ 14. What do the letters on the inside of the Punnett square stand for? ________________________ ___________________________________________________________________________ 15. In corn plants, normal height, N, is dominant to short height, n. Complete these four Punnett squares showing different crosses. Then, shade red all the homozygous dominant offspring. Shade green all the heterozygous offspring. Leave all the homozygous recessive offspring unshaded. N N N n N n N n N N n n N n n n 16. In guinea pigs, short hair, S, is dominant to long hair, s. Complete the following Punnett squares according to the directions given. Then, fill in the blanks beside each Punnett square with the correct numbers. a. One guinea pig is Ss and one is ss. Expected number of offspring: ____ Short hair (SS or Ss) ____ Long hair (ss) b. Both guinea pigs are heterozygous for short hair. Expected number of offspring: ____ Short hair ____ Long hair Part C: Monohybrid Cross Problems - Show your work. 17. Hornless (H) in cattle is dominant over horned (h). A homozygous hornless bull is mated with a homozygous horned cow. What will be the genotype and phenotype of the first generation? P1 F1 2 18. In tomatoes, red fruit (R) is dominant over yellow fruit (r). A plant that is homozygous for red fruit is crossed with a plant that has yellow fruit. What would be the genotypes and phenotypes of the P1 and F1 generations? P1 F1 19. If two of the F1 generation from the above cross were mated, what would be the genotypes and phenotypes of the F2? F1 F2 20. In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries a woman who is heterozygous for tongue rolling. Father’s phenotype ________ Mother’s phenotype _________ Father’s genotype ________ Mother’s genotype _________ What is the probability of this couple having a child who is a tongue roller? ________ 21. Brown eyes in humans are dominant to blue eyes. A brown-eyed man, whose mother was blue-eyed, marries a brown-eyed woman whose father had blue eyes. What is the probability that this couple will have a blue-eyed child? _______ 3