Which of the following description of eye colour is true for fruit fly ?

Options

A. White eye colour is dominant over red eye colour and its gene is located on autosome .
B. Red eye colour dominant over red eye colour and its gene is located on autosome
C. White eye colour is dominant over red eye colour and its gene is located on the X chromosome .
D. Red eye colour dominant over white eye colour and its gene is located on the X chromosome .

Answer

To solve the question regarding the eye color of fruit flies, we need to analyze the genetic traits associated with eye color in Drosophila melanogaster (fruit flies). Here’s a step-by-step breakdown:

### Step 1: Understand the Genetic Basis of Eye Color
In fruit flies, eye color is a trait that is determined by specific genes. The two primary eye colors discussed are red and white.

**Hint:** Remember that traits can be dominant or recessive, and they can be located on different chromosomes.

### Step 2: Identify the Dominance Relationship
The question presents two eye colors: red and white. In fruit flies, red eye color is known to be the dominant trait, while white eye color is recessive. This means that if a fly has at least one allele for red eyes, it will display red eyes.

**Hint:** Dominant traits will mask the expression of recessive traits when both are present.

### Step 3: Determine the Chromosomal Location
The genes responsible for eye color in fruit flies are located on the X chromosome. This is significant because it indicates that the inheritance pattern will follow sex-linked inheritance rules.

**Hint:** Recall that males have one X chromosome and one Y chromosome, while females have two X chromosomes.

### Step 4: Analyze the Inheritance Pattern
Since the gene for eye color is on the X chromosome, males (XY) will express the trait associated with their single X chromosome. Females (XX) will express the trait associated with both of their X chromosomes. Therefore, for a female to express white eyes, she must inherit the recessive allele from both parents.

**Hint:** Consider how traits are inherited differently in males and females due to their sex chromosomes.

### Step 5: Conclusion
Based on the analysis, we conclude that the correct statement regarding eye color in fruit flies is: "Red eye color is dominant over white eye color, and its gene is located on the X chromosome."

**Final Answer:** The correct option is: "Red eye color is dominant over white eye color and its gene is located on the X chromosome."