What percentage of progenies when there is marriage between colourblind father's son and colourblind mother's daughter -

Options

A. 50% sons colour blind
B. 50% daughters carriers
C. 50% daughters normal
D. All of these

Answer

To solve the problem of determining the percentage of progenies when there is a marriage between a colorblind father's son and a colorblind mother's daughter, we can follow these steps:

### Step 1: Understand the Genetic Background
Color blindness is a sex-linked recessive trait carried on the X chromosome. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). A male with color blindness has the genotype XcY (where Xc represents the X chromosome with the colorblind allele), and a female who is a carrier has the genotype XcX (where Xc is the X chromosome with the colorblind allele and X is the normal allele).

### Step 2: Identify the Genotypes of the Parents
- The father (colorblind) has the genotype: **XcY**
- The mother (colorblind) has the genotype: **XcX**

### Step 3: Determine the Possible Gametes
- The father can produce two types of gametes: **Xc** and **Y**.
- The mother can produce two types of gametes: **Xc** and **X**.

### Step 4: Set Up the Punnett Square
We can set up a Punnett square to visualize the possible combinations of gametes from both parents:

| | **Xc** (from mother) | **X** (from mother) |
|---------|-----------------------|----------------------|
| **Xc** (from father) | XcXc (carrier female) | XcX (normal female) |
| **Y** (from father) | XcY (colorblind male) | XY (normal male) |

### Step 5: Analyze the Results
From the Punnett square, we can see the following combinations:
1. XcXc - Carrier Female
2. XcX - Normal Female
3. XcY - Colorblind Male
4. XY - Normal Male

### Step 6: Calculate the Percentages
Now we can calculate the percentages of each type of progeny:
- 1 Carrier Female (XcXc) = 25%
- 1 Normal Female (XcX) = 25%
- 1 Colorblind Male (XcY) = 25%
- 1 Normal Male (XY) = 25%

### Final Result
- 50% of the progenies will be colorblind males (XcY).
- 50% of the progenies will be normal males (XY) and carrier females (XcX).
- Thus, the percentage of progenies that are colorblind is **25%**.

### Summary
The percentage of progenies that will be colorblind when there is a marriage between a colorblind father's son and a colorblind mother's daughter is **25%**.

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