Question

What is the phenotypic ratio?
14. Cross a homozygous dominant plant with a heterozygous plant.

Answer 1

To determine the phenotypic ratio from the cross of a homozygous dominant plant with a heterozygous plant, we need to define the alleles:

- Let’s denote the dominant allele as "A" and the recessive allele as "a."
- A homozygous dominant plant would have the genotype "AA" and a heterozygous plant would have the genotype "Aa."

Now, we can set up the cross:

1. Parent 1 (homozygous dominant): AA
2. Parent 2 (heterozygous): Aa

To find the offspring, we can use a Punnett square:

```
A A
----------------
A | AA | AA |
----------------
a | Aa | Aa |
----------------
```

From the Punnett square, the possible genotypes of the offspring are:

- 2 AA (homozygous dominant)
- 2 Aa (heterozygous)

Now let's consider the phenotypes. Both AA and Aa exhibit the dominant phenotype (A).

Thus, the phenotypic ratio is:

- 4 showing the dominant phenotype (2 AA + 2 Aa)
- 0 showing the recessive phenotype (aa)

Therefore, the phenotypic ratio is **4:0**, which can also be expressed simply as **100% dominant phenotype**.