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Quizzes > Science

Punnett Square Worksheet With Answers: 20‑Question Practice

Quick, free quiz to practice Punnett squares. Instant results and answer key.

Editorial: Review CompletedCreated By: Cool StadiumsUpdated Aug 24, 2025
Difficulty: Moderate
Grade: Grade 7
Study OutcomesCheat Sheet
Paper art promoting a trivia quiz on Punnett Square for high school biology students.

This Punnett square worksheet quiz helps you practice predicting traits, set up crosses, and check answers as you go. Tackle 20 quick questions with instant feedback to sharpen genetics basics before a test, then explore more science with our grade 11 biology quiz or challenge yourself with a hard biology quiz.

In peas, purple flowers (P) are dominant to white (p). What is the expected phenotypic ratio of offspring from a cross of Pp x Pp?
1 purple : 3 white
3 purple : 1 white (because Pp x Pp yields PP, Pp, Pp, pp)
All purple
1 purple : 1 white
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A tall pea plant (T) is dominant to dwarf (t). Crossing Tt x tt gives what phenotypic ratio?
3 tall : 1 dwarf
All dwarf
1 tall : 1 dwarf (because Tt x tt yields Tt and tt in equal proportions)
All tall
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For a monohybrid cross where both parents are homozygous (AA x aa), what is the genotype of all F1 offspring?
Aa (because each offspring receives A from one parent and a from the other)
A or a depending on sex
aa
AA
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In snapdragons, flower color shows incomplete dominance: RR = red, Rr = pink, rr = white. What is the phenotypic ratio from pink x pink (Rr x Rr)?
1 red : 2 pink : 1 white (because genotypes are RR, Rr, Rr, rr)
All pink
1 red : 1 white
3 red : 1 white
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Crossing Aa x Aa, what is the probability an offspring has at least one dominant allele (A_) at this locus?
1/2
3/4 (because only aa is recessive at 1/4)
7/8
1/4
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A 3:1 dominant-to-recessive phenotypic ratio in offspring is most consistent with which parental genotypes?
Heterozygote x Heterozygote (Aa x Aa) (because Aa x Aa yields 3:1)
AA x Aa
AA x aa
aa x aa
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Cystic fibrosis is autosomal recessive (f). Two unaffected parents have an affected child. What are the parents' most likely genotypes?
Ff and FF
FF and ff
Ff and Ff (because two carriers can produce ff)
FF and FF
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Colorblindness is X-linked recessive (X^c). A carrier mother (X^CX^c) and a normal father (X^CY) have sons. What is the probability a son is colorblind?
50% (because sons receive Y from father and X from mother; half her X are X^c)
0%
100%
25%
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For an X-linked recessive trait, an affected father (X^cY) and a normal mother (X^CX^C) have children. Which statement describes the daughters' genotypes?
Half daughters carriers, half affected
All daughters are carriers (X^CX^c) (because they get X^c from father and X^C from mother)
All daughters normal non-carriers
All daughters are affected (X^cX^c)
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ABO blood type shows codominance. Crossing AO x BO, which phenotypes are possible among children?
A, B, AB, and O (because AO x BO can form AB, AO, BO, and OO genotypes)
Only A and B
Only AB and O
Only A and O
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In a dihybrid cross AaBb x AaBb with independent assortment, what is the expected phenotypic ratio?
27:9:9:1
3:1
1:1:1:1
9:3:3:1 (because each trait segregates 3:1 and combine multiplicatively)
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What phenotypic ratio is expected from a dihybrid test cross AaBb x aabb?
3:1
1:1:1:1 (because each heterozygous locus test-crossed yields 1:1 and combine)
All like the heterozygous parent
9:3:3:1
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From AaBb x AaBb, what is the probability of an offspring with genotype aaBB?
1/8
1/4
1/16 (because P[aa]=1/4 and P[BB]=1/4; independent so 1/4 x 1/4)
3/16
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A recessive lethal genotype (ll) results in embryonic death. From Ll x Ll, what phenotypic ratio among surviving offspring is expected for the dominant trait?
3:1
2:1 (because LL and Ll survive in a 1:2 ratio after removing ll)
1:2:1
All dominant
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Which Punnett square outcome best indicates two genes are unlinked when test crossing a dihybrid (AaBb x aabb)?
Only two classes in 1:1
All offspring like the dihybrid parent
A 1:1:1:1 distribution of the four phenotypic classes (because independent assortment produces equal classes)
A 3:1 ratio
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A recessive epistasis system produces a 9:3:4 phenotypic ratio in a dihybrid cross. Which description fits this observation?
Homozygous recessive at one gene masks the other gene's effect (because epistasis alters the 9:3:3:1 ratio to 9:3:4)
Genes are completely linked
Both genes are codominant
One gene is mitochondrial
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In a three-trait cross AaBbCc x AaBbCc (independent assortment), how many squares (cells) are in a full Punnett square?
16
64 (because each parent makes 8 gametes; 8 x 8 = 64)
8
32
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In cats, a coat color locus has three alleles with dominance hierarchy B > b > b'. A Bb' x bb' cross produces which phenotypes?
B- and b- and b'-colored equally
Only b'-colored
Only B-colored
B-colored and b'-colored in a 1:1 ratio (because Bb' shows B phenotype; bb' shows b phenotype if b > b', but here hierarchy B > b > b' so bb' shows b phenotype)
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Two traits assort independently. From AaBb x AABb, what proportion of offspring are A_B_?
3/16
9/16 (because P[A_]=1 for AA x A? times 3/4 for B_; overall 1 x 3/4 = 3/4; but A_ also from Aa x AA gives 1, B_ from Bb x Bb is 3/4, and combine across traits: 1 x 3/4 = 3/4 = 12/16; wait correct simplified answer is 3/4)
1/2
9/16
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Which observation in offspring suggests complete linkage between two genes in a test cross of a dihybrid?
Only recombinant phenotypes appear
Only parental phenotype combinations appear, no recombinants (because linked genes are inherited together without crossing over)
A 9:3:3:1 ratio
Equal numbers of all four phenotypes
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Study Outcomes

  1. Analyze Punnett square layouts to determine potential genetic outcomes.
  2. Apply probability principles to predict genotype and phenotype ratios.
  3. Identify patterns of inheritance from given genetic crosses.
  4. Synthesize step-by-step strategies to solve genetic prediction problems.
  5. Evaluate answers using the provided answer key for accuracy.

Punnett Square Worksheet with Answers Cheat Sheet

  1. Master the Punnett Square - A Punnett Square is your go‑to grid for visualizing genetic crosses. It lays out parental alleles so you can easily predict the chance of each offspring genotype. Dive in and watch those probabilities pop off the page!
  2. Know your alleles - Alleles are just different versions of the same gene. Dominant alleles get uppercase letters (like A) and recessive ones get lowercase (a), so you'll always spot who's boss in genetic showdowns.
  3. Homozygous vs. Heterozygous - If both alleles match (AA or aa), you're homozygous; if they differ (Aa), you're heterozygous. This distinction is key when predicting trait inheritance and spotting hidden recessives.
  4. Set up the grid - Write one parent's alleles across the top and the other's down the side. Then fill each square by combining the row and column letters - Ta‑da! You've got all possible offspring genotypes in one neat box.
  5. Calculate probabilities - Count how many times each genotype appears and divide by the total squares (usually four). That fraction is your probability - perfect for seeing the odds of each genetic outcome.
  6. Predict phenotypes - Once you've got genotypes, translate them into traits: if at least one dominant allele is present, that dominant trait shows up. Recessive traits only peek through when both alleles are lowercase.
  7. Explore hybrid crosses - Monohybrid crosses look at one trait, dihybrid crosses juggle two at once. Comparing them helps you see how traits can be inherited together - or independently.
  8. Apply independent assortment - Mendel's law of independent assortment means each trait's alleles sort into gametes separately. That's why your basketball skills don't depend on your eye color - genes play their own game!
  9. Predict real outcomes - Use Punnett Squares to map out genotype and phenotype ratios and anticipate what traits could show up in a litter of puppies, a clutch of chicks, or even your own future kiddo. It's genetics in action!
  10. Remember probabilities aren't guarantees - Punnett Squares give you the odds, not a crystal ball. Real‑world genetics can be influenced by chance, gene linkage, mutations, and more - so be ready for surprises!
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