Question

How many of the following genotypes possibly represent normal wings in Drosophila?
 (i) \( Vg^+Vg^+ \) 
(ii) \( Vg^+Vg^{ni} \) 
(iii) \( Vg^+Vg^{no} \) 
(iv) \( Vg^+Vg^{st} \) 
(v) \( Vg^+Vg \) 
 

• A. (i), (ii), and (iii) only
• B. (i) and (ii) only
• C. Only (i)
• D. (i), (ii), (iii), (iv), and (v)

Hint:

When evaluating phenotypes, ensure at least one dominant allele is present for the dominant phenotype to express. Homozygous recessive combinations always result in recessive phenotypes.

Answer 1

The Correct Option is D

In Drosophila, normal wing phenotype is dictated by the presence of at least one dominant \( Vg^+ \) allele. Recessive alleles, such as \( Vg^{ni}, Vg^{no}, Vg^{st}, Vg \), result in abnormal wing development exclusively when present in homozygous recessive states.

Step 1: Evaluate each genotype. \( Vg^+Vg^+ \): Both alleles are wild type, leading to normal wings. 

Normal wings. \( Vg^+Vg^{ni} \): The presence of a single dominant \( Vg^+ \) allele ensures normal wings. 

Normal wings. \( Vg^+Vg^{no} \): The presence of a single dominant \( Vg^+ \) allele ensures normal wings. 

Normal wings. \( Vg^+Vg^{st} \): The presence of a single dominant \( Vg^+ \) allele ensures normal wings. 

Normal wings. \( Vg^+Vg \): The presence of a single dominant \( Vg^+ \) allele ensures normal wings. 

Normal wings. Step 2: Tally the genotypes. All five genotypes possess at least one dominant \( Vg^+ \) allele, thus exhibiting normal wings. \[ \text{Genotypes resulting in normal wings} = (i), (ii), (iii), (iv), (v). \] Consequently, the accurate selection is: \[ \mathbf{(D) \ (i), (ii), (iii), (iv), \text{and} (v)}. \]