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प्रश्न
Given below is a schematic representation of the inheritance of the shape of the seeds of garden peas. Answer the questions that follow:
- Which is the dominant and recessive allele of the trait?
- What does the ratio 3 : 1 in the F2 generation represent?
- State Mendel's Law of Dominance.
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उत्तर
- The dominant allele is R (for round seeds), while the recessive allele is r (for wrinkled seeds). This is obvious because only round seeds develop in F1, whereas the wrinkled characteristic is entirely concealed.
- 3:1 indicates that three of the four seeds are spherical and one is wrinkled. That is, 75% of the F2 progeny have round seeds (the dominant characteristic), but only 25% have wrinkled seeds (the recessive trait).
- Mendel's law of dominance states that if an organism has two distinct alleles for a trait, the dominant allele will be expressed, hiding the recessive allele. This means that only the dominant allele determines the organism's phenotype.
संबंधित प्रश्न
Given below are the F2 – phenotypic ratios of two independently carried monohybrid crosses :
(i) 1 : 2 : 1
(ii) 3 : 1
Mention what does each ratio suggest.
A certain couple got four daughters in a sequence and no son. Does it mean that the husband does not produce Y-chromosome bearing sperms? Explain. What is the chance of this couple having a daughter?
A pure tall plant (TT) is crossed with the pure dwarf plant (tt), what would be the F1 and F2 generations? Explain.
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in the F1 generation are then selfed to produce F2 generation of pea plants.
What do the plants of the F1 generation look like?
Genotypic ratio of a monohybrid cross is ______.
In a monohybrid cross of plants with red and white flowered plants, Mendel got only red-flowered plants. On self-pollinating these F1 plants got both red and white flowered plants in 3:1 ratio. Explain the basis of using RR and rr symbols to represent the genotype of plants of parental generation.
In a plant tallness is dominant over dwarfness and red flower is dominant over white. Starting with the parents work out a dihybrid cross. What is standard dihybrid ratio? Do you think the values would deviate if the two genes in question are interacting with each other?
Pooja has green eyes while her parents and brother have black eyes. Pooja’s husband Ravi has black eyes while his mother has green eyes and father has black eyes.
a. On the basis of the above given information, is the green eye colour a dominant or recessive trait? Justify your answer
b. What is the possible genetic makeup of Pooja’s brother’s eye colour?
c. What is the probability that the offspring of Pooja and Ravi will have green eyes? Also, show the inheritance of eye colour in the offspring with the help of a suitable cross.
OR
c. 50% of the offspring of Pooja’s brother are green eyed. With help of cross show how this is possible.
What are the phenotype and genotype of all offspring produced by \[TT \times tt\]?
