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 gametes of the \(SS\) parent are all \(S\), and the gametes of the \(ss\) parent are all \(s\).
• The offspring (\(F_1\) generation) will all have the genotype \(Ss\). This means each offspring has one allele for straight wings (\(S\)) and one allele for curly wings (\(s\)).
• The first option is wrong because offspring have \(Ss\) (not \(SS\)). The second option is wrong as gametes from \(F_1\) (\(Ss\)) can be \(S\) or \(s\). The fourth option is wrong since there are two types of alleles (\(S\) and \(s\)) in the \(F_1\) generation for the wing - type gene.

Answer:

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