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When two strains of white colored flowers are crossed with each other, the F1 generation is all purple flowered. This means both the genes contribute for the purple color. In absence of even one of them, the color is not produced and the flowers are white. This is an example of which type of epistasis ?
- a)Dominant epistasis
- b)Duplicate recessive epistasis
- c)Recessive epistasis
- d)Duplicate dominant epistasis
Correct answer is option 'B'. Can you explain this answer?
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When two strains of white colored flowers are crossed with each other,...
This is an example of duplicate recessive epistasis where the ratio of F2 generation is 9 : 7 instead of 9 : 3 : 3 : 1.
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When two strains of white colored flowers are crossed with each other,...
Epistasis is a phenomenon in genetics where the expression of one gene is dependent on the presence or absence of another gene. There are several types of epistasis, including dominant epistasis, recessive epistasis, and duplicate epistasis. In this case, the example given represents duplicate recessive epistasis.
Duplicate recessive epistasis occurs when the presence of two recessive alleles at different gene loci is required to inhibit the expression of a trait. In other words, the phenotype is only observed when both genes have the recessive alleles, and the dominant alleles at either locus are capable of producing the trait.
Explanation:
When two strains of white-colored flowers are crossed with each other, the F1 generation is all purple-flowered. This suggests that both genes contribute to the production of the purple color. If either one of the genes is absent, the color is not produced, and the flowers remain white.
Let's suppose that the white color is controlled by two genes, gene A and gene B. Both genes have two alleles each, where the dominant allele (A or B) produces the purple color, and the recessive allele (a or b) produces the white color.
- Gene A: A (dominant allele) and a (recessive allele)
- Gene B: B (dominant allele) and b (recessive allele)
When two white-flowered strains are crossed, they would have the genotype aaBB and AAbb. The F1 generation would have the genotype AaBb, where both genes contribute to the production of the purple color.
If we perform a test cross between the F1 generation and a white-flowered strain (aaBB), we would observe the following phenotypic ratio in the F2 generation:
- 9 purple-flowered: A_B_
- 3 white-flowered: aaB_
- 3 white-flowered: A_bb
- 1 white-flowered: aabb
From the phenotypic ratio, we can see that the presence of either one of the dominant alleles (A or B) is enough to produce the purple color. However, if both recessive alleles (a and b) are present, the color is not produced, and the flowers remain white.
Therefore, this example represents duplicate recessive epistasis, where the presence of two recessive alleles (aabb) inhibits the expression of the purple color, and the dominant alleles at either locus (A or B) are capable of producing the purple color.
Hence, the correct answer is option B (Duplicate recessive epistasis).
Duplicate recessive epistasis occurs when the presence of two recessive alleles at different gene loci is required to inhibit the expression of a trait. In other words, the phenotype is only observed when both genes have the recessive alleles, and the dominant alleles at either locus are capable of producing the trait.
Explanation:
When two strains of white-colored flowers are crossed with each other, the F1 generation is all purple-flowered. This suggests that both genes contribute to the production of the purple color. If either one of the genes is absent, the color is not produced, and the flowers remain white.
Let's suppose that the white color is controlled by two genes, gene A and gene B. Both genes have two alleles each, where the dominant allele (A or B) produces the purple color, and the recessive allele (a or b) produces the white color.
- Gene A: A (dominant allele) and a (recessive allele)
- Gene B: B (dominant allele) and b (recessive allele)
When two white-flowered strains are crossed, they would have the genotype aaBB and AAbb. The F1 generation would have the genotype AaBb, where both genes contribute to the production of the purple color.
If we perform a test cross between the F1 generation and a white-flowered strain (aaBB), we would observe the following phenotypic ratio in the F2 generation:
- 9 purple-flowered: A_B_
- 3 white-flowered: aaB_
- 3 white-flowered: A_bb
- 1 white-flowered: aabb
From the phenotypic ratio, we can see that the presence of either one of the dominant alleles (A or B) is enough to produce the purple color. However, if both recessive alleles (a and b) are present, the color is not produced, and the flowers remain white.
Therefore, this example represents duplicate recessive epistasis, where the presence of two recessive alleles (aabb) inhibits the expression of the purple color, and the dominant alleles at either locus (A or B) are capable of producing the purple color.
Hence, the correct answer is option B (Duplicate recessive epistasis).
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When two strains of white colored flowers are crossed with each other, the F1 generation is all purple flowered. This means both the genes contribute for the purple color. In absence of even one of them, the color is not produced and the flowers are white. This is an example of which type of epistasis ?a)Dominant epistasisb)Duplicate recessive epistasisc)Recessive epistasisd)Duplicate dominant epistasisCorrect answer is option 'B'. Can you explain this answer?
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When two strains of white colored flowers are crossed with each other, the F1 generation is all purple flowered. This means both the genes contribute for the purple color. In absence of even one of them, the color is not produced and the flowers are white. This is an example of which type of epistasis ?a)Dominant epistasisb)Duplicate recessive epistasisc)Recessive epistasisd)Duplicate dominant epistasisCorrect answer is option 'B'. Can you explain this answer? for IIT JAM 2024 is part of IIT JAM preparation. The Question and answers have been prepared according to the IIT JAM exam syllabus. Information about When two strains of white colored flowers are crossed with each other, the F1 generation is all purple flowered. This means both the genes contribute for the purple color. In absence of even one of them, the color is not produced and the flowers are white. This is an example of which type of epistasis ?a)Dominant epistasisb)Duplicate recessive epistasisc)Recessive epistasisd)Duplicate dominant epistasisCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for IIT JAM 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for When two strains of white colored flowers are crossed with each other, the F1 generation is all purple flowered. This means both the genes contribute for the purple color. In absence of even one of them, the color is not produced and the flowers are white. This is an example of which type of epistasis ?a)Dominant epistasisb)Duplicate recessive epistasisc)Recessive epistasisd)Duplicate dominant epistasisCorrect answer is option 'B'. Can you explain this answer?.
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