Monohybrid and Dihybrid Cross - Unsolved Practice Set
Chapter: Principles of Inheritance and Variation | Topic: Monohybrid and Dihybrid Cross
MONOHYBRID AND DIHYBRID CROSS - UNSOLVED PRACTICE SET
Topic: Monohybrid and Dihybrid Cross
Multiple Choice Questions
Q1. In a typical monohybrid cross between two heterozygous parents, the expected phenotypic ratio in the F2 generation is:
- 1:1
- 3:1
- 9:3:3:1
- 1:2:1
Q2. The genotypic ratio expected in the F2 generation of a monohybrid cross is:
- 3:1
- 1:2:1
- 9:3:3:1
- 1:1:1:1
Q3. A test cross is performed by crossing an individual showing the dominant phenotype with:
- Another individual of unknown genotype
- A homozygous recessive individual
- A homozygous dominant individual
- Itself
Q4. The classic phenotypic ratio obtained in a dihybrid cross between two heterozygous individuals (F1 × F1) is:
- 3:1
- 1:2:1
- 9:3:3:1
- 1:1
Q5. A Punnett square is primarily used to:
- Measure plant height
- Predict the possible genotype and phenotype combinations of offspring
- Extract DNA
- Count chromosomes
Short Answer Questions
Q6. What is a test cross, and why is it useful in genetics?
Q7. Differentiate between a monohybrid cross and a dihybrid cross.
Q8. Why does a dihybrid cross result in four different phenotypic classes in the F2 generation?
Q9. How does a Punnett square help visualise the outcome of a genetic cross?
Long Answer Questions
Q10. Using a suitable example, explain how a monohybrid cross is carried out, and describe both the phenotypic and genotypic ratios obtained in the F2 generation.
Q11. Describe how a dihybrid cross between two heterozygous parents (for two independently assorting traits) results in the classic 9:3:3:1 ratio in the F2 generation.
APPLICATION / ANALYSIS
Q12. A plant breeder crosses a tall, heterozygous pea plant (Tt) with a short pea plant (tt) to determine the genotype of the tall plant with certainty. Explain which type of cross this represents, and what results would confirm the tall plant's genotype.
Q13. In a dihybrid cross between two pea plants heterozygous for seed shape and seed colour (RrYy × RrYy), calculate the expected number of plants with round, green seeds if 160 seeds are obtained in total, assuming the classic dihybrid ratio holds.