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प्रश्न
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
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उत्तर १
No. This information is not sufficient to determine which of the traits – blood group A or O – is dominant. This is because we do not know about the blood group of all the progeny.
Blood group A can be genotypically AA or AO. Hence, the information is incomplete to draw any such conclusion.
उत्तर २
- If blood group A is dominant: The mother would be homozygous for the recessive allele O. The father, with blood group A, could be either homozygous or heterozygous. If he is homozygous, he would not carry the allele O. The daughter would inherit allele O only from her mother, but since allele O is recessive, it would not be expressed. However, if the father is heterozygous, he would also have an allele for O. In this case, the daughter could inherit allele O from both parents and if homozygous for the recessive allele O, she would have blood group O.
- If blood group O is dominant: The father would lack allele O in order to have blood group A. The mother could be either homozygous or heterozygous for allele O. In both situations, the daughter would inherit one allele for blood group O, and since allele O is dominant, it would always be expressed, resulting in the daughter having blood group O.
Thus, since the daughter could have blood group O in both scenarios, we cannot definitively say which blood group is dominant.
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संबंधित प्रश्न
How did Mendel interpret his results to show that traits may be dominant or recessive? Describe briefly.
In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F1 generation. However, on selfing the F1 generation pea plants, he obtained both tall and short plants in F2 generation. On the basis of above observations with other angiosperms also, can the scientist arrive at a law? If yes, explain the law. If not, give justification for your answer.
A cross was made between pure breeding pea plants one with round and green seeds and the other with wrinkled and yellow seeds.
(a) Write the phenotype of F1 progeny. Give reason for your answer.
(b) Write the different types of F2 progeny obtained along with their ration when F1 progeny was selfed.
List any two contrasting characters other than height that Mendel used in his experiments in pea plants.
Mendel in one of his experiments with pea plants crossed a variety having round seed with one having wrinkled seeds. Write his observations, giving reasons, of F1 and F2 progeny
To perform an experiment to identify the different parts of an embryo of a dicot seed, first of all you require a dicot seed. Select dicot seeds from the following group:
Wheat, Gram, Maize, Pea, Barley, Ground-nut
(A) Wheat, Gram and Pea
(B) Gram, Pea and Ground-nut
(C) Maize, Pea and Barley
(D) Gram, Maize and Ground-nut
Fill in the following blank with suitable word .
In pea plants, the gene for dwarfness is ..............whereas that for tallness is ............ .
What is the genotype of dwarf plants whose parental cross always produces tall offspring?
What sizes of plants are produced if both parents have genes Tt?
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :
Round seed
In order to ensure that he had pure-breeding plants for his experiments, Mendel :
(a) cross-fertilised each variety with each other
(b) let each variety self fertilise for several generations
(c) removed the female parts of the plants
(d) removed the male parts of the plants.
Pure-bred round-yellow pea seeds have genotype RRYY and the pure-bred wrinkled-green pea seeds have genotype rryy. Keeping this in mind, write the phenotypes of the following genotypes of hybrid pea seeds :
(a) Rryy
(b) rrYy
(c) rrYY
(d) RrYy
(e) RRyy
Only one of the following characteristic of the parents can be inherited by their children. This one is:
If we pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F1 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F1 generation but appeared in F2 generation, mentioning the reason for the same.
Why are the traits acquired during the life time of an individual not inherited? Explain.
In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of eyes of the persons having combinations
(i) Bb and (ii) BB?
Two pink coloured flowers on crossing resulted in 1 red, 2 pink and 1 white flower progeny. The nature of the cross will be
A cross between pea plant with white flowers (vv) and pea plant with violet flowers (VV) resulted in F2 progeny in which ratio of violet (VV) and white (vv) flowers will be ______.
