Read the given paragraph to answerIn a certain plant, yellow fruit col...
When YyRr is crossed with double recessive parent then genotypic and phenotypic ratio will be 1:1:1:1
Phenotypic ratio = 1 yellow round : 1 yellow oval : 1 green round : 1 green and oval. This represent a test cross.
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Read the given paragraph to answerIn a certain plant, yellow fruit col...
Explanation:
To understand the correct answer, let's first analyze the genotypes of the parents and the possible combinations in the offspring:
- Parent 1: YyRr (yellow fruit color, round shape)
- Parent 2: yyrr (green fruit color, oval shape)
Possible gametes:
- Parent 1: YR, Yr, yR, yr
- Parent 2: yr, yr
F1 generation:
When the parents are crossed, the possible combinations of gametes are:
- YR yr
- Yr yr
- yR yr
- yr yr
The resulting offspring will have the following genotypes:
- YyRr (yellow fruit color, round shape)
- Yyrr (yellow fruit color, oval shape)
- yyRr (green fruit color, round shape)
- yyrr (green fruit color, oval shape)
Predicted phenotypes:
- Yellow, round fruit: YyRr, Yyrr, yyRr (3)
- Yellow, oval fruit: Yyrr (1)
- Green, round fruit: yyRr (1)
- Green, oval fruit: yyrr (1)
Explanation of the options:
a) 9:3:3:1 ratio of phenotypes only: This ratio suggests that there should be nine plants with yellow, round fruit, three plants with yellow, oval fruit, three plants with green, round fruit, and one plant with green, oval fruit. However, this does not match the possible phenotypes we determined earlier.
b) 9:3:3:1 ratio of genotypes only: This ratio suggests that there should be nine plants with the genotype YyRr, three plants with the genotype Yyrr, three plants with the genotype yyRr, and one plant with the genotype yyrr. Again, this does not match the possible genotypes we determined earlier.
c) 1:1:1:1 ratio of phenotypes only: This ratio suggests that there should be an equal number of plants with each phenotype. However, this does not match the possible phenotypes we determined earlier.
d) 1:1:1:1 ratio of phenotypes and genotypes: This ratio suggests that there should be an equal number of plants with each phenotype and genotype. This matches the possible phenotypes and genotypes we determined earlier. Therefore, option D is the correct answer.
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