Question

If a heterozygous tall plant (Tt) is crossed with a dwarf plant (tt), what will be the phenotypic ratio of the offspring?
 

• A. 1 Tall : 3 Dwarf
• B. 1 Tall : 1 Dwarf
• C. All Tall
• D. All Dwarf

Hint:

A Punnett square is a powerful tool to visualize genetic crosses and determine the probability of offspring genotypes and phenotypes. In cases where you have dominant and recessive traits, always check the genotype of the parents before drawing the Punnett square!

Answer 1

The Correct Option is B

To solve the problem, we need to understand basic genetics concepts involving dominant and recessive traits and how they are inherited through crosses.

1. Understanding the Concepts:

- Each plant has two alleles (versions of a gene) for height: T (tall) and t (dwarf).
- The tall trait (T) is dominant over dwarf (t).
- A heterozygous tall plant has genotype Tt, meaning one tall allele and one dwarf allele.
- A dwarf plant has genotype tt, meaning two dwarf alleles.
- When these plants are crossed, their offspring’s genotypes and phenotypes depend on the combinations of alleles they inherit.

2. Set Up the Cross:

Parents:
- Heterozygous tall (Tt)
- Dwarf (tt)

3. Possible Gametes:

• Heterozygous tall (Tt) can produce two types of gametes: T and t.
• Dwarf (tt) can produce only one type of gamete: t.

4. Punnett Square:

	t (from tt)
T (from Tt)	Tt
t (from Tt)	tt

5. Offspring Genotypes and Phenotypes:

• Tt: Tall (because T is dominant)
• tt: Dwarf

6. Phenotypic Ratio:

- Number of tall offspring = 1
- Number of dwarf offspring = 1
- Ratio = 1 Tall : 1 Dwarf

Final Answer:

The phenotypic ratio of the offspring will be 1 tall : 1 dwarf.