Black (B) color in guinea pigs is dominant to white (b).A female from a pure-bre

Question

Black (B) color in guinea pigs is dominant to white (b).A female from a pure-breeding black strain is crossed with a male from a pure-breeding white strain.Answer the following questions about the cross.

Parental cross (P generation cross) – draw a Punnett square (1 pt):

Parental Gametes (HINT: when you join these two haploid gametes together, you get a diploid F1 generation organism) (1 pt):

Female gives::__________         Male gives::__________

F1 Genotype ratio (the alleles for the gene in the offspring - how many and what are they?) (1 pt):

F1 Phenotype ratio (coat color of offspring – what color and how many?) (1 pt):

F1 cross and Punnett square (draw a Punnett square for two F1 offspring) (1 pt):

F2 Genotype ratio (the alleles for the gene in the offspring - there should be 3 combinations) (1 pt):

F2 Phenotype ratio (coat color of offspring and how many; there should be 2 different colors) (1 pt):

Explanation / Answer

Answer:

Based on given information:

Parental Gametes (HINT: when you join these two haploid gametes together, you get a diploid F1 generation organism) (1 pt):

Female gives::_b gametes_         Male gives::_B gametes_

F1 Genotype ratio (the alleles for the gene in the offspring - how many and what are they?) (1 pt):

F1 Phenotype ratio (coat color of offspring – what color and how many?) (1 pt):

F1 cross and Punnett square (draw a Punnett square for two F1 offspring) (1 pt):

The genotype BB = 1/4 or 25%

The genotype Bb = 2/4 = 50%

The genotype bb= 1/4 = 25%

Phenotype Black color = 3/4 = 75%

Phenotype white color = 1/4 = 25%

F2 Genotype ratio (the alleles for the gene in the offspring - there should be 3 combinations) (1 pt):

F2 Phenotype ratio (coat color of offspring and how many; there should be 2 different colors) (1 pt):

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