In Drosophila, the Recessive Allele P, When Homozygous, Determines Pink

question 89

Multiple Choice

In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, whereas the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.Assume that no crossing over occurs, and that the F₂ generation is produced by interbreeding the F₁ progeny.For the cross PPByBy  ppbyby, what is the genotype ratio of the F₂ generation?

• A) 3 PPByBy : 1 ppbyby
• B) 1 PPByBy : 3 ppbyby
• C) 1 PPByBy : 2 PpByby: 1 ppbyby
• D) 3 PpByby : 1 ppbyby
• E) 1 PpByby : 3 PPByBy

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Definitions:

Microelectrode

A tiny electrode used to record electrical signals from single neurons.

Millivolts

A unit of electric potential equal to one thousandth of a volt.

Refractory Period

A period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation.

Action Potential

A brief electrical impulse that enables the transmission of signals along the neuron, crucial for nerve impulse propagation.