Mendelian GeneticsMendelian GeneticsSample word problemsSample word problems

1. In labrador retrievers, black fur 1. In labrador retrievers, black fur (B) is dominant to yellow fur (b)(B) is dominant to yellow fur (b)

Predict the offspring from a cross Predict the offspring from a cross between two homozygous black between two homozygous black

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2. In labrador retrievers, black fur 2. In labrador retrievers, black fur (B) is dominant to yellow fur (b)(B) is dominant to yellow fur (b)

Predict the offspring from a cross Predict the offspring from a cross between two homozygous yellow between two homozygous yellow

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3. In labrador retrievers, black fur 3. In labrador retrievers, black fur (B) is dominant to yellow fur (b)(B) is dominant to yellow fur (b)

Predict the offspring from a cross Predict the offspring from a cross between a heterozygous male between a heterozygous male

and a yellow femaleand a yellow female

6. Albinism (a) is recessive6. Albinism (a) is recessive

Predict the offspring Predict the offspring of a cross between:of a cross between:

Two heterozygous Two heterozygous pythonspythons

Two albino pythonsTwo albino pythons A homozygous normal A homozygous normal

python with an albino python with an albino pythonpython

A heterozygous python A heterozygous python with an albino pythonwith an albino python

7.The rooster has “grizzly” feathers. 7.The rooster has “grizzly” feathers. The hen has solid color feathers.The hen has solid color feathers.

This rooster and this This rooster and this hen have 10 offspring, hen have 10 offspring, all with solid color all with solid color feathers.feathers.

What does that tell What does that tell you about the feather you about the feather color trait?color trait?

What are the What are the genotypes of the genotypes of the rooster, the hen, and rooster, the hen, and all the offspring?all the offspring?

8. Drosophila melanogaster8. Drosophila melanogasterThe common fruit flyThe common fruit fly

If a grey fly If a grey fly mates with a mates with a white fly and white fly and all the all the offspring are offspring are grey, which grey, which color is color is dominant?dominant?

9. Drosophila melanogaster9. Drosophila melanogasterThe common fruit flyThe common fruit fly

Based on what Based on what you determined you determined from the last from the last question, what question, what would you would you predict from a predict from a cross between cross between two two heterozygous heterozygous fruit flies?fruit flies?

10. Drosophila melanogaster10. Drosophila melanogasterThe common fruit flyThe common fruit fly

Vestigial wings is Vestigial wings is a recessive a recessive mutation. What mutation. What offspring will offspring will result from a result from a cross between 2 cross between 2 vestigial winged vestigial winged flies?flies?

11. In fruit flies, stubble bristles (b) 11. In fruit flies, stubble bristles (b) is a recessive mutationis a recessive mutation

Predict the Predict the offspring from the offspring from the following crosses:following crosses:

Two heterozygous Two heterozygous normal fliesnormal flies

Two stubble bristle Two stubble bristle fliesflies

A heterozygous A heterozygous normal fly with a normal fly with a stubble bristle flystubble bristle fly

4. Widow’s peak (H) is a dominant 4. Widow’s peak (H) is a dominant traittrait

These two have These two have a baby with a a baby with a smooth hairline. smooth hairline. Determine Determine their genotypes their genotypes and the and the genotype of the genotype of the babybaby

5. Widow’s peak (H) is a dominant 5. Widow’s peak (H) is a dominant traittrait

Based on what Based on what you know from you know from the last the last question, make question, make a prediction a prediction about what about what might happen if might happen if these two had these two had kids togetherkids together

12. Dihybrid Cross – Determine if the genes for 12. Dihybrid Cross – Determine if the genes for wing shape and eye color are Linked or wing shape and eye color are Linked or

Independent Independent

P1 = P1 = Straight wings, Red eyes X Curly wings, Orange eyesStraight wings, Red eyes X Curly wings, Orange eyesF1 = F1 = all Straight wings, Red eyesall Straight wings, Red eyesP2 = P2 = Straight wings, Red eyes x Straight wings, Red eyesStraight wings, Red eyes x Straight wings, Red eyesF2 =F2 = 36 straight wing, red eye36 straight wing, red eye

12 straight wing, orange eye12 straight wing, orange eye13 curly wing, red eye13 curly wing, red eye 4 curly wing, orange eye4 curly wing, orange eye

13.Which F2 13.Which F2 phenophenotypes (2 correct answers) types (2 correct answers) would you would you onlyonly expect from Independent expect from Independent

Assortment? Assortment?

P1 = P1 = Straight wings, Red eyes X Curly wings, Orange eyesStraight wings, Red eyes X Curly wings, Orange eyesF1 = F1 = all Straight wings, Red eyesall Straight wings, Red eyesP2 = P2 = Straight wings, Red eyes x Straight wings, Red eyesStraight wings, Red eyes x Straight wings, Red eyesF2 =F2 = 36 straight wing, red eye36 straight wing, red eye

12 straight wing, orange eye12 straight wing, orange eye13 curly wing, red eye13 curly wing, red eye 4 curly wing, orange eye4 curly wing, orange eye

14. Dihybrid Cross – Determine if the genes for 14. Dihybrid Cross – Determine if the genes for eye color and bristles are Linked or Independent eye color and bristles are Linked or Independent

P1 = P1 = red eyes, normal bristles X brown eyes, stubble bristlesred eyes, normal bristles X brown eyes, stubble bristlesF1 = F1 = all red eye, normal bristleall red eye, normal bristleP2 = P2 = red eyes, normal bristles X red eyes, normal bristles red eyes, normal bristles X red eyes, normal bristles F2 =F2 = 28 red eyes, normal bristles 28 red eyes, normal bristles

0 red eyes, stubble bristles0 red eyes, stubble bristles 0 brown eye, normal bristles0 brown eye, normal bristles 9 brown eye, stubble bristle9 brown eye, stubble bristle

15. Are the genes for eye color and bristles on the 15. Are the genes for eye color and bristles on the same chromosome or on different chromosomes? same chromosome or on different chromosomes?

P1 = P1 = red eyes, normal bristles X brown eyes, stubble bristlesred eyes, normal bristles X brown eyes, stubble bristlesF1 = F1 = all red eye, normal bristleall red eye, normal bristleP2 = P2 = red eyes, normal bristles X red eyes, normal bristles red eyes, normal bristles X red eyes, normal bristles F2 =F2 = 28 red eyes, normal bristles 28 red eyes, normal bristles

0 red eyes, stubble bristles0 red eyes, stubble bristles 0 brown eye, normal bristles0 brown eye, normal bristles 9 brown eye, stubble bristle9 brown eye, stubble bristle