Punnett Squares and Genetics Worksheet Generator
Monohybrid and dihybrid crosses, pedigrees, and probability with exact fractions. No AI, no credits.
Grades 7 – 12No account needed
Practice sheets with Punnett squares drawn by code, genotype and phenotype ratios as exact fractions, probability questions, and pedigree charts. Every answer is computed by two independent methods (full square versus product rule, exhaustive enumeration versus Mendelian rules). No AI, so it never uses a generation credit.
What students practice
- Biology
- Genetics
- Probability
Live sample sheet
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Name: ____________________Date: ____________
Punnett Squares and Genetics
1. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a YY offspring?
2. In seed shape, round (R) is dominant to wrinkled (r). A Rr plant is crossed with a Rr plant. What is the probability of getting a rr offspring?
3. In pod color, green (G) is dominant to yellow (g). A Gg plant is crossed with a Gg plant. What is the probability of getting a GG offspring?
4. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a Yy offspring?
5. In plant height, tall (T) is dominant to short (t). A plant with genotype Tt is crossed with a plant with genotype tt. What are the expected genotype and phenotype ratios of the offspring?
6. In flower color, purple (P) is dominant to white (p). A Pp plant is crossed with a Pp plant. What is the probability of getting a Pp offspring?
7. In flower color, purple (P) is dominant to white (p). A Pp plant is crossed with a Pp plant. What is the probability of getting a pp offspring?
8. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype Rr. What are the expected genotype and phenotype ratios of the offspring?
9. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype YY. What are the expected genotype and phenotype ratios of the offspring?
10. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype rr. What are the expected genotype and phenotype ratios of the offspring?
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Answer Key — Punnett Squares and Genetics
1. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a YY offspring?
Solution:
Parent 1 (Yy) gametes: Y, y
Parent 2 (Yy) gametes: Y, y
Method A (counting): count YY cells / total cells
Method B (product rule): multiply probabilities at each locus
P(YY) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
2. In seed shape, round (R) is dominant to wrinkled (r). A Rr plant is crossed with a Rr plant. What is the probability of getting a rr offspring?
Solution:
Parent 1 (Rr) gametes: R, r
Parent 2 (Rr) gametes: R, r
Method A (counting): count rr cells / total cells
Method B (product rule): multiply probabilities at each locus
P(rr) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
3. In pod color, green (G) is dominant to yellow (g). A Gg plant is crossed with a Gg plant. What is the probability of getting a GG offspring?
Solution:
Parent 1 (Gg) gametes: G, g
Parent 2 (Gg) gametes: G, g
Method A (counting): count GG cells / total cells
Method B (product rule): multiply probabilities at each locus
P(GG) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
4. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a Yy offspring?
Solution:
Parent 1 (Yy) gametes: Y, y
Parent 2 (Yy) gametes: Y, y
Method A (counting): count Yy cells / total cells
Method B (product rule): multiply probabilities at each locus
P(Yy) = 1/2 = 50.0%
Both methods agree: yes
Answer: 1/2; 50.0%
5. In plant height, tall (T) is dominant to short (t). A plant with genotype Tt is crossed with a plant with genotype tt. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Tt) produces gametes: T, t
Parent 2 (tt) produces gametes: t, t
Punnett square (2×2):
T | Tt | Tt
t | tt | tt
Genotype ratio: 2 Tt : 2 tt
Phenotype ratio: 2 undefined : 2 short (tall : short)
Check (product rule): Tt=1/2, tt=1/2 — agrees
Answer: 2 Tt : 2 tt; 2 undefined : 2 short
6. In flower color, purple (P) is dominant to white (p). A Pp plant is crossed with a Pp plant. What is the probability of getting a Pp offspring?
Solution:
Parent 1 (Pp) gametes: P, p
Parent 2 (Pp) gametes: P, p
Method A (counting): count Pp cells / total cells
Method B (product rule): multiply probabilities at each locus
P(Pp) = 1/2 = 50.0%
Both methods agree: yes
Answer: 1/2; 50.0%
7. In flower color, purple (P) is dominant to white (p). A Pp plant is crossed with a Pp plant. What is the probability of getting a pp offspring?
Solution:
Parent 1 (Pp) gametes: P, p
Parent 2 (Pp) gametes: P, p
Method A (counting): count pp cells / total cells
Method B (product rule): multiply probabilities at each locus
P(pp) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
8. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype Rr. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Rr) produces gametes: R, r
Parent 2 (Rr) produces gametes: R, r
Punnett square (2×2):
R | RR | Rr
r | Rr | rr
Genotype ratio: 2 Rr : 1 RR : 1 rr
Phenotype ratio: 3 undefined : 1 wrinkled (round : wrinkled)
Check (product rule): RR=1/4, Rr=1/2, rr=1/4 — agrees
Answer: 2 Rr : 1 RR : 1 rr; 3 undefined : 1 wrinkled
9. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype YY. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Yy) produces gametes: Y, y
Parent 2 (YY) produces gametes: Y, Y
Punnett square (2×2):
Y | YY | YY
y | Yy | Yy
Genotype ratio: 2 YY : 2 Yy
Phenotype ratio: 4 undefined (yellow : green)
Check (product rule): YY=1/2, Yy=1/2 — agrees
Answer: 2 YY : 2 Yy; 4 undefined
10. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype rr. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Rr) produces gametes: R, r
Parent 2 (rr) produces gametes: r, r
Punnett square (2×2):
R | Rr | Rr
r | rr | rr
Genotype ratio: 2 Rr : 2 rr
Phenotype ratio: 2 undefined : 2 wrinkled (round : wrinkled)
Check (product rule): Rr=1/2, rr=1/2 — agrees
Answer: 2 Rr : 2 rr; 2 undefined : 2 wrinkled
Answers computed by code and double-checked by two independent methods.
Assumptions and Conventions
Assumptions:
- Complete dominance unless stated otherwise.
- Allele notation: uppercase = dominant, lowercase = recessive.
- Independent assortment is assumed for dihybrid crosses.
- Probabilities describe offspring of this one cross, not a population.
- Pedigree symbols: square = male, circle = female, filled = affected, half-filled = carrier.
Conventions:
- Course: biology
- Difficulty: standard
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Frequently asked questions
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Can I print the Punnett Squares and Genetics without signing up?
Yes. This tool computes answers by code, so you can generate, preview and print worksheet without an account. A free account adds saving and student links.
How are the answers computed?
Every answer is computed by code and verified by a second independent method. No AI is used.
What grades is the Punnett Squares and Genetics for?
This tool fits Grades 7 – 12.
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Name: ____________________Date: ____________
Punnett Squares and Genetics
1. In seed shape, round (R) is dominant to wrinkled (r). A Rr plant is crossed with a Rr plant. What is the probability of getting a Rr offspring?
2. In plant height, tall (T) is dominant to short (t). A Tt plant is crossed with a Tt plant. What is the probability of getting a Tt offspring?
3. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype yy. What are the expected genotype and phenotype ratios of the offspring?
4. In plant height, tall (T) is dominant to short (t). A Tt plant is crossed with a Tt plant. What is the probability of getting a TT offspring?
5. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype rr. What are the expected genotype and phenotype ratios of the offspring?
6. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a yy offspring?
7. In flower color, purple (P) is dominant to white (p). A plant with genotype Pp is crossed with a plant with genotype Pp. What are the expected genotype and phenotype ratios of the offspring?
8. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype Yy. What are the expected genotype and phenotype ratios of the offspring?
9. In flower color, purple (P) is dominant to white (p). A plant with genotype Pp is crossed with a plant with genotype PP. What are the expected genotype and phenotype ratios of the offspring?
10. In pod color, green (G) is dominant to yellow (g). A Gg plant is crossed with a Gg plant. What is the probability of getting a GG offspring?
Made with TeachSpark
Answer Key — Punnett Squares and Genetics
1. In seed shape, round (R) is dominant to wrinkled (r). A Rr plant is crossed with a Rr plant. What is the probability of getting a Rr offspring?
Solution:
Parent 1 (Rr) gametes: R, r
Parent 2 (Rr) gametes: R, r
Method A (counting): count Rr cells / total cells
Method B (product rule): multiply probabilities at each locus
P(Rr) = 1/2 = 50.0%
Both methods agree: yes
Answer: 1/2; 50.0%
2. In plant height, tall (T) is dominant to short (t). A Tt plant is crossed with a Tt plant. What is the probability of getting a Tt offspring?
Solution:
Parent 1 (Tt) gametes: T, t
Parent 2 (Tt) gametes: T, t
Method A (counting): count Tt cells / total cells
Method B (product rule): multiply probabilities at each locus
P(Tt) = 1/2 = 50.0%
Both methods agree: yes
Answer: 1/2; 50.0%
3. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype yy. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Yy) produces gametes: Y, y
Parent 2 (yy) produces gametes: y, y
Punnett square (2×2):
Y | Yy | Yy
y | yy | yy
Genotype ratio: 2 Yy : 2 yy
Phenotype ratio: 2 undefined : 2 green (yellow : green)
Check (product rule): Yy=1/2, yy=1/2 — agrees
Answer: 2 Yy : 2 yy; 2 undefined : 2 green
4. In plant height, tall (T) is dominant to short (t). A Tt plant is crossed with a Tt plant. What is the probability of getting a TT offspring?
Solution:
Parent 1 (Tt) gametes: T, t
Parent 2 (Tt) gametes: T, t
Method A (counting): count TT cells / total cells
Method B (product rule): multiply probabilities at each locus
P(TT) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
5. In seed shape, round (R) is dominant to wrinkled (r). A plant with genotype Rr is crossed with a plant with genotype rr. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Rr) produces gametes: R, r
Parent 2 (rr) produces gametes: r, r
Punnett square (2×2):
R | Rr | Rr
r | rr | rr
Genotype ratio: 2 Rr : 2 rr
Phenotype ratio: 2 undefined : 2 wrinkled (round : wrinkled)
Check (product rule): Rr=1/2, rr=1/2 — agrees
Answer: 2 Rr : 2 rr; 2 undefined : 2 wrinkled
6. In seed color, yellow (Y) is dominant to green (y). A Yy plant is crossed with a Yy plant. What is the probability of getting a yy offspring?
Solution:
Parent 1 (Yy) gametes: Y, y
Parent 2 (Yy) gametes: Y, y
Method A (counting): count yy cells / total cells
Method B (product rule): multiply probabilities at each locus
P(yy) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
7. In flower color, purple (P) is dominant to white (p). A plant with genotype Pp is crossed with a plant with genotype Pp. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Pp) produces gametes: P, p
Parent 2 (Pp) produces gametes: P, p
Punnett square (2×2):
P | PP | Pp
p | Pp | pp
Genotype ratio: 2 Pp : 1 PP : 1 pp
Phenotype ratio: 3 undefined : 1 white (purple : white)
Check (product rule): PP=1/4, Pp=1/2, pp=1/4 — agrees
Answer: 2 Pp : 1 PP : 1 pp; 3 undefined : 1 white
8. In seed color, yellow (Y) is dominant to green (y). A plant with genotype Yy is crossed with a plant with genotype Yy. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Yy) produces gametes: Y, y
Parent 2 (Yy) produces gametes: Y, y
Punnett square (2×2):
Y | YY | Yy
y | Yy | yy
Genotype ratio: 2 Yy : 1 YY : 1 yy
Phenotype ratio: 3 undefined : 1 green (yellow : green)
Check (product rule): YY=1/4, Yy=1/2, yy=1/4 — agrees
Answer: 2 Yy : 1 YY : 1 yy; 3 undefined : 1 green
9. In flower color, purple (P) is dominant to white (p). A plant with genotype Pp is crossed with a plant with genotype PP. What are the expected genotype and phenotype ratios of the offspring?
Solution:
Parent 1 (Pp) produces gametes: P, p
Parent 2 (PP) produces gametes: P, P
Punnett square (2×2):
P | PP | PP
p | Pp | Pp
Genotype ratio: 2 PP : 2 Pp
Phenotype ratio: 4 undefined (purple : white)
Check (product rule): PP=1/2, Pp=1/2 — agrees
Answer: 2 PP : 2 Pp; 4 undefined
10. In pod color, green (G) is dominant to yellow (g). A Gg plant is crossed with a Gg plant. What is the probability of getting a GG offspring?
Solution:
Parent 1 (Gg) gametes: G, g
Parent 2 (Gg) gametes: G, g
Method A (counting): count GG cells / total cells
Method B (product rule): multiply probabilities at each locus
P(GG) = 1/4 = 25.0%
Both methods agree: yes
Answer: 1/4; 25.0%
Answers computed by code and double-checked by two independent methods.
Assumptions and Conventions
Assumptions:
- Complete dominance unless stated otherwise.
- Allele notation: uppercase = dominant, lowercase = recessive.
- Independent assortment is assumed for dihybrid crosses.
- Probabilities describe offspring of this one cross, not a population.
- Pedigree symbols: square = male, circle = female, filled = affected, half-filled = carrier.
Conventions:
- Course: biology
- Difficulty: standard
Made with TeachSpark
Punnett Squares and Genetics - Biology - Sex-linked traits
Punnett squares, pedigrees, and probability with exact fractions. No AI, no credits.