Question
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What is the step-by-step process of a monohybrid cross?

Verified Answer

A monohybrid cross is a genetic cross that studies the inheritance of a single trait between two organisms. It follows a systematic process to determine how traits are passed to offspring.

Step-by-step process of a monohybrid cross:

1. Selection of parent generation (P generation)
Choose two pure-breeding parents with contrasting traits:
Example: Tall plant (TT) × Dwarf plant (tt)

2. Formation of gametes
Each parent produces gametes carrying one allele:

  • TT → T, T

  • tt → t, t

3. Fertilization (F₁ generation)
Gametes combine randomly:

  • T × t → all offspring are Tt (heterozygous)

Result: All F₁ plants are tall (dominant trait expressed)

4. Self-crossing of F₁ generation
F₁ plants (Tt × Tt) are crossed to produce F₂ generation

5. Formation of gametes from F₁
Each Tt plant produces two types of gametes: T and t

6. Formation of F₂ generation (Punnett square):

Possible combinations:

  • TT

  • Tt

  • Tt

  • tt

Genotypic ratio:
1 TT : 2 Tt : 1 tt

Phenotypic ratio:
3 Tall : 1 Dwarf

Conclusion:

  • Demonstrates the law of dominance and segregation

  • Shows predictable inheritance pattern

In simple terms: A monohybrid cross tracks how one trait is inherited from parents to offspring using allele combinations.