Question

What is the difference between gynandromorphs and intersexes in {Drosophila?}

• A. Intersexes are genetically similar throughout their bodies, whereas gynandromorph consists of two genetically different tissues
• B. Intersexes are not genetically similar throughout their bodies, whereas gynandromorph genetically similar throughout their bodies
• C. Intersexes are sterile, whereas gynandromorphs are genetically similar throughout their bodies
• D. Intersexes are genetically similar throughout their bodies, whereas gynandromorph consists of four genetically different tissues

Hint:

Remember the prefixes:

\textbf{Inter-} means "between," so intersexes have a phenotype between male and female, caused by a uniform but abnormal genetic ratio.
\textbf{Gyn-} means female and \textbf{andro-} means male. A gynandromorph is a single organism with both male and female parts, resulting from a genetic mosaic. \end{itemize}

Answer 1

The Correct Option is A

Step 1: Concept Overview:
This question explores intersexes and gynandromorphs in {Drosophila}, two types of sexual development abnormalities resulting from distinct genetic mechanisms.

Step 2: Detailed Explanation:
- Intersexes: In {Drosophila}, sex determination relies on the X chromosome to autosome ratio (X/A). Intersex individuals possess an intermediate X/A ratio between a normal male (0.5) and a normal female (1.0), such as 0.67 (2X chromosomes/3 sets of autosomes). Importantly, all cells within an intersex fly share the same abnormal genetic makeup. They are genetically uniform throughout, exhibiting an intermediate sexual phenotype.
- Gynandromorphs: Gynandromorphs are genetic mosaics, composed of cells with different genotypes. In {Drosophila}, this usually arises when a female (XX) zygote loses an X chromosome during early mitosis. This creates two cell lines: XX (female) and XO (male). Subsequent cell divisions lead to an organism with patches of male and female tissue. Thus, a gynandromorph comprises two genetically distinct tissues.

Step 3: Option Analysis:
- (A) Correctly describes both: intersexes are genetically uniform, while gynandromorphs are mosaics of two genetically different tissues.
- (B) Incorrectly reverses the descriptions.
- (C) While intersexes are typically sterile, it incorrectly claims gynandromorphs are genetically similar.
- (D) Correctly describes intersexes but incorrectly states gynandromorphs consist of four tissues; it's typically two.

Step 4: Conclusion:
Option (A) accurately distinguishes between intersexes and gynandromorphs.