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: Understanding the problem:
In this case, we are dealing with a genetic cross between two pea plants that produce 50% tall and 50% short pea plants in the offspring. The trait for plant height follows Mendelian inheritance, where tall (T) is dominant and short (t) is recessive. Tall plants will have the genotype TT or Tt, and short plants will have the genotype tt.

Step 2: Analyzing the offspring ratio:
The offspring have a 50% tall and 50% short phenotype. This suggests a 1:1 ratio, which is typically seen in a monohybrid cross between a heterozygous (Tt) and a homozygous recessive (tt) parent.

Step 3: Analyzing the parental genotypes:
- If one parent is heterozygous (Tt) and the other is homozygous recessive (tt), the possible offspring genotypes from this cross will be:
- Tt (tall) with a 50% probability
- tt (short) with a 50% probability
This results in the 50% tall and 50% short ratio in the offspring, matching the given condition.

Step 4: Conclusion:
The gene combination of the parental pea plants must be Tt and tt to produce a 1:1 ratio of tall to short pea plants in the offspring.

Correct Answer: Tt and tt