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When a heterozygous dominant is crossed ...

When a heterozygous dominant is crossed with homozygous recessive than ratio of progeny will be

A

`1 : 1 `

B

`3 : 1 `

C

`2 : 1`

D

`1 : 2 : 1 `

Text Solution

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The correct Answer is:
To solve the problem of determining the ratio of progeny when a heterozygous dominant is crossed with a homozygous recessive, we can follow these steps: ### Step-by-Step Solution: 1. **Define the Genotypes**: - The heterozygous dominant genotype can be represented as **Tt** (where **T** is the dominant allele and **t** is the recessive allele). - The homozygous recessive genotype is represented as **tt**. 2. **Determine the Gametes**: - The gametes produced by the heterozygous dominant (Tt) will be **T** and **t**. - The gametes produced by the homozygous recessive (tt) will be **t** and **t**. 3. **Set Up the Punnett Square**: - Create a Punnett square to visualize the cross: ``` T | t ---------------- t | Tt | tt ---------------- t | Tt | tt ``` 4. **Analyze the Offspring**: - From the Punnett square, we can see the possible genotypes of the offspring: - **Tt** (heterozygous dominant) - 2 occurrences - **tt** (homozygous recessive) - 2 occurrences 5. **Determine the Phenotypic Ratio**: - The phenotypes corresponding to these genotypes are: - **Tt** will express the dominant trait (e.g., tall plants). - **tt** will express the recessive trait (e.g., short plants). - Thus, the ratio of phenotypes will be: - Tall plants (Tt): 2 - Short plants (tt): 2 - Therefore, the phenotypic ratio is **1:1**. ### Final Answer: The ratio of progeny when a heterozygous dominant is crossed with a homozygous recessive is **1:1**. ---
To solve the problem of determining the ratio of progeny when a heterozygous dominant is crossed with a homozygous recessive, we can follow these steps: ### Step-by-Step Solution: 1. **Define the Genotypes**: - The heterozygous dominant genotype can be represented as **Tt** (where **T** is the dominant allele and **t** is the recessive allele). - The homozygous recessive genotype is represented as **tt**. ...
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