Here are the solutions for the Punnett square worksheet. Remember, the capital letter represents the dominant trait (the one that shows up if it's present), and the lowercase letter is the recessive trait (it only shows up if there are two of them).
1) A green pea plant (Gg) is crossed with a yellow pea plant (gg).
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Parents: Gg x gg
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Punnett Square:
* Top row: g, g
* Side column: G, g
* Inside boxes: Gg, Gg, gg, gg
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Genotype Ratio: 2 Gg : 2 gg (which simplifies to 1:1)
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Phenotype Description: Since 'G' is dominant, Gg is Green. Since 'g' is recessive, gg is Yellow.
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Result: 2 Green pea plants : 2 Yellow pea plants
2) A tall plant (TT) is crossed with a tall plant (Tt).
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Parents: TT x Tt
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Punnett Square:
* Top row: T, t
* Side column: T, T
* Inside boxes: TT, Tt, TT, Tt
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Genotype Ratio: 2 TT : 2 Tt (simplifies to 1:1)
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Phenotype Description: Both TT and Tt contain the dominant 'T', so they are all Tall.
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Result: 4 Tall plants : 0 Short plants
3) A tall plant (Tt) is crossed with a short plant (tt).
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Parents: Tt x tt
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Punnett Square:
* Top row: t, t
* Side column: T, t
* Inside boxes: Tt, Tt, tt, tt
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Genotype Ratio: 2 Tt : 2 tt (simplifies to 1:1)
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Phenotype Description: Tt is Tall (dominant). tt is Short (recessive).
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Result: 2 Tall plants : 2 Short plants
4) A red flower (Rr) is crossed with a white flower (rr).
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Parents: Rr x rr
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Punnett Square:
* Top row: r, r
* Side column: R, r
* Inside boxes: Rr, Rr, rr, rr
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Genotype Ratio: 2 Rr : 2 rr (simplifies to 1:1)
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Phenotype Description: Rr is Red (dominant). rr is White (recessive).
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Result: 2 Red flowers : 2 White flowers
5) A white flower (rr) is crossed with a white flower (rr).
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Parents: rr x rr
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Punnett Square:
* Top row: r, r
* Side column: r, r
* Inside boxes: rr, rr, rr, rr
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Genotype Ratio: 4 rr
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Phenotype Description: All offspring are rr, which is White.
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Result: 0 Red flowers : 4 White flowers
6) A black chicken (BB) is crossed with a black chicken (BB).
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Parents: BB x BB
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Punnett Square:
* Top row: B, B
* Side column: B, B
* Inside boxes: BB, BB, BB, BB
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Genotype Ratio: 4 BB
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Phenotype Description: All offspring are BB, which is Black.
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Result: 4 Black chickens : 0 other color
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Final Answer:
1)
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Genotype: 2 Gg : 2 gg
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Phenotype: 2 Green : 2 Yellow
2)
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Genotype: 2 TT : 2 Tt
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Phenotype: 4 Tall : 0 Short
3)
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Genotype: 2 Tt : 2 tt
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Phenotype: 2 Tall : 2 Short
4)
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Genotype: 2 Rr : 2 rr
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Phenotype: 2 Red : 2 White
5)
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Genotype: 4 rr
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Phenotype: 0 Red : 4 White
6)
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Genotype: 4 BB
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Phenotype: 4 Black : 0 Other
Parent Tip: Review the logic above to help your child master the concept of punnett square worksheet 1.
