1. Mendelian Genetics Sample word problems

2. 1. In labrador retrievers, black fur (B) is dominant to yellow fur (b) Predict the offspring from a cross between two homozygous black labs

3. 2. In labrador retrievers, black fur (B) is dominant to yellow fur (b) Predict the offspring from a cross between two homozygous yellow labs

4. 3. In labrador retrievers, black fur (B) is dominant to yellow fur (b) Predict the offspring from a cross between a heterozygous male and a yellow female

5. 6. Albinism (a) is recessive Predict the offspring of a cross between:  Two heterozygous pythons  Two albino pythons  A homozygous normal python with an albino python  A heterozygous python with an albino python

6. 7.The rooster has “grizzly” feathers. The hen has solid color feathers. This rooster and this hen have 10 offspring, all with solid color feathers.  What does that tell you about the feather color trait?  What are the genotypes of the rooster, the hen, and all the offspring?

7. 8. Drosophila melanogaster The common fruit fly If a grey fly mates with a white fly and all the offspring are grey, which color is dominant?

8. 9. Drosophila melanogaster The common fruit fly Based on what you determined from the last question, what would you predict from a cross between two heterozygous fruit flies?

9. 10. Drosophila melanogaster The common fruit fly Vestigial wings is a recessive mutation. What offspring will result from a cross between 2 vestigial winged flies? Vestigial wings is a recessive mutation. What offspring will result from a cross between 2 vestigial winged flies?

10. 11. In fruit flies, stubble bristles (b) is a recessive mutation Predict the offspring from the following crosses:  Two heterozygous normal flies  Two stubble bristle flies  A heterozygous normal fly with a stubble bristle fly

11. 4. Widow’s peak (H) is a dominant trait These two have a baby with a smooth hairline. Determine their genotypes and the genotype of the baby

12. 5. Widow’s peak (H) is a dominant trait Based on what you know from the last question, make a prediction about what might happen if these two had kids together

13. 12. Dihybrid Cross – Determine if the genes for wing shape and eye color are Linked or Independent P1 = Straight wings, Red eyes X Curly wings, Orange eyes F1 = all Straight wings, Red eyes P2 = Straight wings, Red eyes x Straight wings, Red eyes F2 = 36 straight wing, red eye 12 straight wing, orange eye 13 curly wing, red eye 4 curly wing, orange eye 4 curly wing, orange eye

14. 13.Which F2 phenotypes (2 correct answers) would you only expect from Independent Assortment? P1 = Straight wings, Red eyes X Curly wings, Orange eyes F1 = all Straight wings, Red eyes P2 = Straight wings, Red eyes x Straight wings, Red eyes F2 = 36 straight wing, red eye 12 straight wing, orange eye 13 curly wing, red eye 4 curly wing, orange eye 4 curly wing, orange eye

15. 14. Dihybrid Cross – Determine if the genes for eye color and bristles are Linked or Independent P1 = red eyes, normal bristles X brown eyes, stubble bristles F1 = all red eye, normal bristle P2 = red eyes, normal bristles X red eyes, normal bristles F2 = 28 red eyes, normal bristles 0 red eyes, stubble bristles 0 red eyes, stubble bristles 0 brown eye, normal bristles 0 brown eye, normal bristles 9 brown eye, stubble bristle 9 brown eye, stubble bristle

16. 15. Are the genes for eye color and bristles on the same chromosome or on different chromosomes? P1 = red eyes, normal bristles X brown eyes, stubble bristles F1 = all red eye, normal bristle P2 = red eyes, normal bristles X red eyes, normal bristles F2 = 28 red eyes, normal bristles 0 red eyes, stubble bristles 0 red eyes, stubble bristles 0 brown eye, normal bristles 0 brown eye, normal bristles 9 brown eye, stubble bristle 9 brown eye, stubble bristle