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प्रश्न
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.
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उत्तर
On crossing red and white flower only red colour flower appeared in the F1 generation. But the white colour flower again appear in the F2 generation which is raised out of the F1 individuals only. Mendel reasoned that there is a factor of each and every character. Accordingly, there has to be one factor (R) for red flower and other one factor (r) for white flower. In case, an organism possess only one copy of the gene then the possibility of reappearance of white flower in the F2 generation of the given cross is not there. Also the ratio (3:1 of red and white) indicates that each organism must possess two copies of a particular gene.
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संबंधित प्रश्न
When a cross is made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be:
- Tall and green.
- Dwarf and green.
Mention whether the cross is a monohybrid or dihybrid.
Name the conditions when both the alleles are identical?
What do you understand by the terms phenotype and genotype?
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?
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.
Which type of plants was missing in the F1 generation but reappeared in the F2 generation?
Differentiate between inherited and acquired characters. Give one example for each type.
Give reasons why acquired characters are not inherited.
Genotypic ratio of a monohybrid cross is ______.
When a tall plant with rounded seeds (TTRR) is grossed with a Dwarf plant with wrinkled seeds (ttrr) the F1 generation consists of tall plants with rounded seeds. How many types of gametes the F1 plant would produce?
Punnett square is used to know
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.
In a cross between red coloured and white coloured flowers, when plants with red coloured flowers of F1 generation were self pollinated, plants of F2 generation were obtained in which 75% of plants were with red flowers and 2.5% plants were with white flowers.
Explain the inheritance of traits in the above cross with the help of a flow chart only along with the ratio of plants obtained.
