Question

a scientist is studying fruit fly wings. straight wings are dominant, and curly wings are recessive. which statement correctly describes the f₁ generation if a straight - winged parent is crossed with a curly - winged parent and if both parents are true breeding?
the offspring will have two genes for straight wings.
the offspring will produce only gametes that have genes for curly wings.
the offspring will have one allele for straight wings and one allele for curly wings.
the offspring will have only one kind of allele for the gene that determines wing type.

Explanation:

Let's assume the allele for straight wings is \(S\) (dominant) and for curly wings is \(s\) (recessive). A true - breeding straight - winged parent has the genotype \(SS\), and a true - breeding curly - winged parent has the genotype \(ss\).
When \(SS\times ss\), using the Punnett square method (a common genetic cross - analysis tool), the \(F_1\) generation will all have the genotype \(Ss\).

• Option 1: Offspring with two genes for straight wings (\(SS\)) is incorrect because one parent has \(ss\).
• Option 2: Offspring producing only gametes with \(s\) (curly - winged allele) is wrong. Since the genotype is \(Ss\), gametes can be \(S\) or \(s\).
• Option 3: With genotype \(Ss\), the offspring has one allele for straight (\(S\)) and one for curly (\(s\)), which is correct.
• Option 4: Having only one kind of allele (either \(S\) or \(s\)) is incorrect as the cross \(SS\times ss\) gives \(Ss\) (two different alleles for the wing - type gene).

Answer:

The offspring will have one allele for straight wings and one allele for curly wings.