Questions on Punnett Squares
20 multiple-choice questions about Punnett Squares, each with five alternatives, followed by the answers at the end.
Multiple-Choice Questions: Punnett Squares
1. What is the main purpose of a Punnett square?
A) To determine DNA sequences
B) To predict the probability of offspring genotypes
C) To identify mutations
D) To measure gene expression
E) To map chromosomes
2. In a Punnett square, what do the letters outside the grid represent?
A) Possible offspring genotypes
B) Parent alleles
C) Phenotypes of offspring
D) Mutation rates
E) Environmental factors
3. If a cross is between two heterozygous individuals (Aa x Aa), what is the expected genotypic ratio?
A) 1:1
B) 3:1
C) 1:2:1
D) 2:2
E) 4:0
4. In a monohybrid Punnett square, how many possible offspring genotypes are there when crossing two heterozygotes?
A) 1
B) 2
C) 3
D) 4
E) 5
5. Which of these shows a correct genotype for a homozygous dominant individual?
A) Aa
B) aa
C) AA
D) AB
E) Bb
6. How many boxes are in a typical Punnett square for a monohybrid cross?
A) 1
B) 2
C) 3
D) 4
E) 6
7. In a dihybrid cross Punnett square, how many boxes are there?
A) 4
B) 8
C) 9
D) 16
E) 20
8. What does each box inside a Punnett square represent?
A) A possible gamete from a parent
B) A possible genotype of offspring
C) A mutation site
D) A chromosome pair
E) An environmental effect
9. In a cross between homozygous dominant (AA) and homozygous recessive (aa), what will be the genotype of the offspring?
A) AA only
B) aa only
C) Aa only
D) AA and aa
E) Aa and aa
10. What is the phenotypic ratio expected from a monohybrid cross of two heterozygous parents if the trait is dominant-recessive?
A) 1:1
B) 3:1
C) 1:2:1
D) 2:2
E) 4:0
11. If the alleles are represented by T (tall) and t (short), what are the possible gametes of a Tt individual?
A) TT and tt
B) T only
C) t only
D) T or t
E) TT only
12. How is a heterozygous genotype represented in a Punnett square?
A) AA
B) aa
C) Aa
D) aA only
E) Both C and D
13. What kind of traits can be predicted with a Punnett square?
A) Only dominant traits
B) Only recessive traits
C) Both dominant and recessive traits
D) Only environmental traits
E) Only traits controlled by multiple genes
14. In a dihybrid cross, what are the possible gamete combinations for an individual with genotype AaBb?
A) AB, ab
B) AB, Ab, aB, ab
C) Aa, Bb
D) AB only
E) AaBb only
15. Which term describes the physical appearance of an organism based on its genotype?
A) Genotype
B) Phenotype
C) Allele
D) Mutation
E) Chromosome
16. If two heterozygous parents (Aa) are crossed, what is the probability that their offspring will be homozygous recessive (aa)?
A) 25%
B) 50%
C) 75%
D) 100%
E) 0%
17. What information do Punnett squares NOT provide?
A) Probability of genotypes
B) Probability of phenotypes
C) Actual number of offspring
D) Possible allele combinations
E) Patterns of inheritance
18. Which of the following is an example of a genotype?
A) Tall
B) Round seeds
C) Aa
D) Brown eyes
E) Curly hair
19. In a Punnett square, how are recessive alleles usually represented?
A) Capital letters
B) Numbers
C) Lowercase letters
D) Symbols
E) Greek letters
20. If a Punnett square shows 1 AA : 2 Aa : 1 aa genotype ratio, what is the phenotypic ratio assuming complete dominance?
A) 1:2:1
B) 3:1
C) 1:1
D) 2:2
E) 4:0
- Questions Mendel’s Second Law – Law of Independent Assortment
- Questions on Mendel’s First Law – Law of Segregation
- Questions on Life Cycle
Answer Key
1. B
2. B
3. C
4. C
5. C
6. D
7. D
8. B
9. C
10. B
11. D
12. E
13. C
14. B
15. B
16. A
17. C
18. C
19. C
20. B
Dive into the groundbreaking science of neurotransmitters—your brain’s invisible architects—in Chemical Harmony: How Neurotransmitters Shape Our Lives (2025). This meticulously researched book reveals how serotonin, dopamine, GABA, and other brain chemicals silently orchestrate every aspect of your existence, from decision-making and relationships to mental health and emotional resilience.Click here to buy
👉 +3000 Biology Questions with Answers Key.
Share Online!
