You are working with two recessive mutations in Drosophila: e causes ebony and ro causes rough eyes. You cross a true-breeding strain of ebony flies (e e, ) with a true-breeding strain of rough-eyed flies ( , ro ro). You then cross the F1 to a true-breeding strain with ebony body and rough eyes. a) What are the predicted F2 genotype proportions if e and ro are on separate chromosomes

The predicted F2 genotype proportions are 1:1:1:1

Explanation:

Available data:

A- Cross a true-breeding strain of ebony flies (e e, ++) with a true-breeding strain of rough-eyed flies (++, ro ro)

Parental)    e e , + +      x       + + , ro ro

Gametes) e+   e+   e+   e+    +ro   +ro   +ro   +ro

Punnet square)         e+       e+        e+      e+

                    +ro    +e+ro  +e+ro  +e+ro  +e+ro

                    +ro    +e+ro  +e+ro  +e+ro  +e+ro

                    +ro    +e+ro  +e+ro  +e+ro  +e+ro

                    +ro    +e+ro  +e+ro  +e+ro  +e+ro

F1) 100% +e+ro

B- Cross the F1 to a true-breeding strain with ebony body and rough eyes.

Parental)     +e,+ro     x      ee, roro

Gametes) ++  ro+  e+  ero    ero  ero  ero  ero

Punnet square)         ++         +ro        e+       ero

                    ero    +e+ro   +eroro   ee+ro  eeroro

                    ero    +e+ro   +eroro   ee+ro  eeroro

                    ero    +e+ro   +eroro   ee+ro  eeroro

                    ero    +e+ro   +eroro   ee+ro  eeroro

F2) 4/16=1/4 +e,+ro

     4/16=1/4  +e,roro

     4/16=1/4  ee,+ro

     4/16=1/4  ee,roro

The predicted F2 genotype proportions are 1:1:1:1

You can also calculate it by making the punnet square for each gene and then multipling the genotypic proportions, like this:

Parental)                     e +  x  e e                   + ro   x   ro ro

Gametes)                 e   +   e   e                  +   ro       ro   ro

Punnet Squares)         e        +                             ro       +

                             e     ee      +e                  ro    roro    +ro

                              e      ee      +e                 ro    roro    +ro

F1) 1/2 ee                                                 F1) 1/2 +ro

     1/2 +e                                                      1/2 roro

F2 genotype proportions)

+e,+ro = 1/2 +e  x  1/2 +ro= 1/4 +e,+ro

+e,roro= 1/2 +e  x  1/2 roro= 1/4 +e,roro

ee,+ro= 1/2 ee  x  1/2 +ro= 1/4 ee,+ro

ee,roro= 1/2 ee  x  1/2 roro= 1/4 ee,roro

the organisms are not adapted to live in some communities or habitats.

[ answer ]

foliated

[ explanation ]

foliation forms in a rock when pressure squeezes the rock together. the rock then has a design of many different color little lines. there are three types of foliated rock. the types are slate, schist, and gneiss. each type of foliated rock is different based on grain size and foliation characteristics. the lines appear when the rock has been under pressure.

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