In Fruit Flies,the Recessive Pr and Cn Mutations Cause Brown

question 52

Multiple Choice

In fruit flies,the recessive pr and cn mutations cause brown and bright-red eyes,respectively (wild-type flies have brick-red eyes) .The double mutant pr cn combination has orange eyes.A female who has wild-type eyes is crossed to an orange-eyed male.Their progeny have the following distribution of eye colours: $$\begin{array} { | l | r | } \hline \text { wild-type } & 8 \\\hline \text { brown } & 241 \\\hline \text { bright-red } & 239 \\\hline \text { orange } & 12 \\\hline & 500 \\\hline\end{array}$$
What is the map distance between the pr and cn genes?

• A) 20 m.u.
• B) 2 m.u.
• C) 4 m.u.
• D) 46 m.u.
• E) 8 m.u.

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Definitions:

Primary Key

A unique identifier for each record in a database, used to ensure that each row represents a unique instance of the entity modeled by the table.

Secondary Key

A database attribute used for sorting and/or indexing data, which is not the primary key.

Relational Database Model

Data model based on the simple concept of tables in order to capitalize on characteristics of rows and columns of data.

Two-Dimensional

Pertaining to an object or image that has width and height but no depth, often used in reference to graphics or shapes on a surface.