Question

A cross made between two pea plants produces 50% tall and 50% short pea plants. The gene combination of the parental pea plants must be

• A. Tt and Tt
• B. TT and Tt
• C. Tt and tt
• D. TT and tt

Answer 1

The Correct Option is C

Step 1: Problem Definition:
Two pea plants produce offspring with a 50% tall and 50% short phenotype. Plant height inheritance is Mendelian, with tall (T) dominant and short (t) recessive. Genotypes for tall plants are TT or Tt, and for short plants are tt.

Step 2: Offspring Ratio Analysis:
The observed 50% tall and 50% short ratio in offspring is a 1:1 ratio. This ratio is characteristic of a monohybrid cross between a heterozygous parent (Tt) and a homozygous recessive parent (tt).

Step 3: Parental Genotype Determination:
Consider a cross between a heterozygous parent (Tt) and a homozygous recessive parent (tt). The possible offspring genotypes and their probabilities are:
- Tt (tall): 50% probability
- tt (short): 50% probability
This yields the observed 50% tall and 50% short offspring ratio.

Step 4: Conclusion:
To achieve a 1:1 ratio of tall to short pea plants in the offspring, the parental genotypes must be Tt and tt.

Correct Answer: Tt and tt