1.  The correct answer is 2. They are RL and Rl. 

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2.       Parents:  YyDd   x  YyDd 

          Punnett square: 

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3.  Parents:  YYdd   x  yyDD 

          Punnett square: 

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4. Parents:  YyDd   x  yydd  

          Punnett square: 

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5. Parents:  YyDd   x  Yydd 

          Punnett square: 
 

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6. Parents:  YyDd   x  YyDD 

          Punnett square: 

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7. Parents:  YyDD   x  yydd 

          Punnett square: 

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8. YyDd      Two sets of genes are represented by this genotype. They are "Y"  and "D". 

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9.   Four alleles are represented by this genotype -  Y,  y,  D,   d. 

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10.   This represents a diploid cell because the alleles are in pairs. 

       YYDD  = diploid                  YD    = haploid 
       SsFFGgDd = diploid             SFgd = haploid 

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 If a yellow sphere-shaped fruit plant is crossed with a green disk-shaped plant, give the genotypes of the parents when the F1 ratio is as follows: 

1 yellow disk-shaped 
1 yellow sphere-shaped 
1 green disk-shaped 
1 green sphere 
 
11. Since the problem refers to two phenotypes, this is a dihybrid problem. Therefore you would set the problem as follows: 

Draw four lines and label two as P1 and two as P2. Each line represents a single set of genes for the parents. Each parent has two sets of genes because this is a dihybrid problem. 

     P1        _____      _____         X      P2 _____      ______ 
 
                color        shape                         color         shape 

Since parent one is yellow and sphere, it must have at least one large "Y" and two small  "d".  Parent two is green and disk, it must have at least two small  "y"  and one large "D".. See below. 

                  Y              dd                              yy            D 
     P1        _____      _____         X      P2 _____      ______ 
 

Now examine the  F1 offspring. 

Remember all offspring must receive one allele from each parent. Since some of the offspring are green, each parent must have a small "y" allele present. Therefore parent one must be Yy. Since some of the offspring are sphere, each parent must have a small "d" allele present. Therefore parent two must be Dd  and 

                                        Yy          dd                           yy             Dd 
  the answer is :   P1        _____      _____         X      P2 _____      ______ 
 
Your can work this problem using Punnett square to see you obtain a 1:1:1:1 ratio to check  your answer. 
 
 

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 If a yellow disk-shaped fruit plant is crossed with a green disk-shaped plant produce the following phenotype ratio, what are the  genotypes of the parents? 

3 yellow disk-shaped 
1 yellow sphere-shaped 
3 green disk-shaped 
1 green sphere YyDD x yydd 
 
12. Since the problem refers to two phenotypes, this is a dihybrid problem. Therefore you would set the problem as follows: 

Draw four lines and label two as P1 and two as P2. Each line represents a single set of genes for the parents. Each parent has two sets of genes because this is a dihybrid problem. 

     P1        _____      _____         X      P2 _____      ______ 
 
                color        shape                         color         shape 

Since parent one is yellow and disk, it must have at least one large "Y" and one large   "D".  Parent two is green and disk, it must have at least two small  "y"  and one large "D".. See below. 

                  Y              D                              yy            D 
     P1        _____      _____         X      P2 _____      ______ 
 

Now examine the  F1 offspring. 

Remember all offspring must receive one allele from each parent. Since some of the offspring are green, each parent must have a small "y" allele present. Therefore parent one must be Yy. Since some of the offspring are sphere, each parent must have a small "d" allele present. Therefore parent two must be Dd  and 

                                        Yy          Dd                           yy             Dd 
  the answer is :   P1        _____      _____         X      P2 _____      ______ 
 
Your can work this problem using Punnett square to see you obtain a 3:1:3:1 ratio to check  your answer. 
 
 
 

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 Give the genotypes of the parents when both parents are yellow disk-shaped and produce the following offspring: 

10 green disk-shaped 
5 green sphere-shaped 
29 yellow disk-shaped 
11 yellow sphere-shaped 
 
13. Since the problem refers to two phenotypes, this is a dihybrid problem. Therefore you would set the problem as follows: 

The difference is this problem is that raw numbers are being used in place of ratios. You should be able to turn these numbers into ratios. What would be the approximate ratio  involved in this problem?  1: 2: 2.1: 6 

This will eventually equate to a  9: 3: 3: 1 ratio 

Draw four lines and label two as P1 and two as P2. Each line represents a single set of genes for the parents. Each parent has two sets of genes because this is a dihybrid problem. 

     P1        _____      _____         X      P2 _____      ______ 
 
                color        shape                         color         shape 

Since parent one is yellow and disk, it must have at least one large "Y" and one large   "D".  Parent two is yellow  and disk, it must have at least one large  "Y"  and one large "D".. See below. 

                  Y              D                              Y            D 
     P1        _____      _____         X      P2 _____      ______ 
 

Now examine the  F1 offspring. 

Remember all offspring must receive one allele from each parent. Since some of the offspring are green, each parent must have a small "y" allele present. Therefore parent one must be Yy. Since some of the offspring are sphere, each parent must have a small "d" allele present. Therefore parent two must be Dd  and 

                                        Yy          Dd                           Yy             Dd 
  the answer is :   P1        _____      _____         X      P2 _____      ______ 
 
Your can work this problem using Punnett square to see you obtain a 9:3:3:1 ratio to check  your answer. 
 
 
 

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Give the genotypes of the parents when the following offspring are produced. 

22 green disk-shaped 
23 green sphere-shaped 
25 yellow disk-shaped 
21 yellow sphere-shaped 
 . 
14. Since the problem refers to two phenotypes, this is a dihybrid problem. Therefore you would set the problem as follows: 

The difference is this problem is that raw numbers are being used in place of ratios. You should be able to turn these numbers into ratios. What would be the approximate ratio  involved in this problem?  1: 1.2 : 1 : 1.2 

This will eventually equate to a  1: 1: 1: 1 ratio 
 

Draw four lines and label two as P1 and two as P2. Each line represents a single set of genes for the parents. Each parent has two sets of genes because this is a dihybrid problem. 

     P1        _____      _____         X      P2 _____      ______ 
 
                color        shape                         color         shape 

 
Now examine the  F1 offspring. 

Remember all offspring must receive one allele from each parent. Since some of the offspring are Yellow and Disk than a "Y" and a "D" must be in one or both of the parents. 

                 Y              D 
     P1        _____      _____         X      P2 _____      ______ 
 
Since some of the offspring are green, each parent must have a small "y" allele present. Therefore parent one must be Yy. Since some of the offspring are sphere, each parent must have a small "d" allele present. 

                 Yy              Dd                               y             d 
     P1        _____      _____         X      P2 _____      ______ 
 
Nearly one half of the offspring are yellow and one half are green, also one half are disk and one half are sphere. What must the missing alleles be to get a 1:1 ratio? 

                                        Yy          Dd                           yy             dd 
  the answer is :   P1        _____      _____         X      P2 _____      ______ 
 
Your can work this problem using Punnett square to see you obtain a 1:1:1:1 ratio to check  your answer. 
 
 
 

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15.    GGss  x   ggSs,  Ggss  x  ggSS, GGss x  ggSS, or  Ggss  x ggSs 
      Four combinations. 

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16.   Parents are  GGSS  x  gg ss 
 
 
 

       F1 offspring are all  GgSs    "gray and straight wings" 
 

       F2   9 gray and straight wings 
              3 gray and curved wings 
              3 ebony and straight wings 
              1 ebony and curved wings 
 

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 State the genotypes of the Drosophila parents if a gray body straight-winged and ebony body straight-winged should produce the following: 

19 ebony body straight-winged 
5   ebony body curved-winged 
20 gray body straight winged 
7   gray body curved-winged 
 
17. Since the problem refers to two phenotypes, this is a dihybrid problem. Therefore you would set the problem as follows: 

The difference is this problem is that raw numbers are being used in place of ratios. You should be able to turn these numbers into ratios. What would be the approximate ratio  involved in this problem?  1: 1.2 : 3.6 : 4 

This will eventually equate to a  1: 3: 1: 3 ratio 
 

Draw four lines and label two as P1 and two as P2. Each line represents a single set of genes for the parents. Each parent has two sets of genes because this is a dihybrid problem. 

     P1        _____      _____         X      P2 _____      ______ 
                                wing                                           wing 
                color        shape                         color         shape 

 
Since parent one is gray and straight , it must have at least one large "G" and one large   "S".  Parent two is ebony and straight, it must have at least two small  "g"  and one large "S".. See below. 

                  G              S                              gg            S 
     P1        _____      _____         X      P2 _____      ______ 
 

Now examine the  F1 offspring. 

Remember all offspring must receive one allele from each parent. Since some of the offspring are ebony, each parent must have a small "g" allele present. Therefore parent one must be Gg. Since some of the offspring are curved winged, each parent must have a small "s" allele present. Therefore both parents  must be Ss  and 

                                        Gg          Ss                           gg             Ss 
  the answer is :   P1        _____      _____         X      P2 _____      ______ 
 
Your can work this problem using Punnett square to see you obtain a 3:1:3:1 ratio to check  your answer. 

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18.   Since all of the offspring are straight wing, one of the parents must be SS, the other parent may be SS, Ss, or ss.  Since three fourth are gray, one parent must be Gg and the other parent must also be Gg. 
 

Therefore  there are several answers: 

   GgSS x GgSS,  GgSS x GgSs, GgSS x  Ggss 
 

 
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19.Since all of the offspring are ebony body, both of the parents must be gg. 
Since one half  are straight winged, one parent must be Ss and the other parent must  be ss. 
 

Therefore  the answer is :   ggSs  x  ggss 

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20. 

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21. 

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22. 

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23. 

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24. 
 

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