Principles of Inheritance and Variation
- In a certain plant, red fruit (R) is dominant over yellow fruit (r) and tallness (T) is dominant over shortness (t) .If a plant with RRTt genotype is crossed with a plant rrtt genotype, what will be the percentage of tall plants with red fruits in the progeny?
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Ratio = 1: 1 red fruit yellow fruitCorrect Option: A
Ratio = 1: 1 red fruit yellow fruit
- A self-fertilizing trihybrid plant forms
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A self-fertilizing trihybrid plant forms 8 different gametes and 64 different zygotes.
The genotype of trihybrid plant is AaBbCc.
Number of gametes formed = 2n = 23 = 8
Here n = no. of heterozygosity = 3 in present case.
No. of zygotes formed = 82 = 64.Correct Option: A
A self-fertilizing trihybrid plant forms 8 different gametes and 64 different zygotes.
The genotype of trihybrid plant is AaBbCc.
Number of gametes formed = 2n = 23 = 8
Here n = no. of heterozygosity = 3 in present case.
No. of zygotes formed = 82 = 64.
- A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperms will be abh?
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Chance of getting a = 1 2 Chance of getting b = 1 2 Chance of getting b = 1 2 Chance of getting sperms with abh = 1 × 1 × 1 = 1 2 2 2 8
Correct Option: A
Chance of getting a = 1 2 Chance of getting b = 1 2 Chance of getting b = 1 2 Chance of getting sperms with abh = 1 × 1 × 1 = 1 2 2 2 8
- The recessive genes located on X-chromosome in humans are always
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Males have only one X - chromosome. Hence any gene present on the one X - chromosome expresses itself n males. Females have two X- chromosomes. The mutant allele must be present on both the X-Chromosomes to express itself phenotypically. If only one copy of allele present, then the female only becomes a carrier showing no external manifestation of the gene. Sublethal condition can never arise in males.
Correct Option: C
Males have only one X - chromosome. Hence any gene present on the one X - chromosome expresses itself n males. Females have two X- chromosomes. The mutant allele must be present on both the X-Chromosomes to express itself phenotypically. If only one copy of allele present, then the female only becomes a carrier showing no external manifestation of the gene. Sublethal condition can never arise in males.
- Lack of independent assortment of two genes A and B in fruit fly Drosophila is due to
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The lack of independent assortment in sweet pea and Drosophila is due to linkage.
Correct Option: C
The lack of independent assortment in sweet pea and Drosophila is due to linkage.
