The genotype of a plant showing the dominat phenotype can be determined by :

Options

A. Back cross
B. Test cross
C. Dihybrid cross
D. Pedigree analysis

Answer

To determine the genotype of a plant showing the dominant phenotype, we can follow these steps:

### Step 1: Understand the Phenotype and Genotype
- The phenotype refers to the observable traits of an organism, while the genotype refers to the genetic makeup. A dominant phenotype can be expressed by either a homozygous dominant genotype (AA) or a heterozygous genotype (Aa).

### Step 2: Conduct a Test Cross
- To determine the genotype of the plant with the dominant phenotype, we perform a test cross. This involves crossing the plant in question (which shows the dominant phenotype) with a plant that has a double recessive genotype (aa).

### Step 3: Analyze the Offspring
- After performing the test cross, we observe the offspring. The phenotypic ratio of the offspring will help us infer the genotype of the parent with the dominant phenotype.
- If all offspring display the dominant phenotype, the genotype of the dominant parent is likely homozygous dominant (AA).
- If there is a mix of offspring showing both dominant and recessive phenotypes (1:1 ratio), the genotype of the dominant parent is heterozygous (Aa).

### Step 4: Conclusion
- Based on the results of the test cross, we can confidently determine whether the plant showing the dominant phenotype is homozygous (AA) or heterozygous (Aa).

### Final Answer
- The genotype of a plant showing the dominant phenotype can be determined by a **test cross**.

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