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प्रश्न
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?
उत्तर
Daughter or son is a matter of chance for Y- or X-chromosome carrying sperm to fertilize the egg. It is always 50% The couple got four daughters as a matter of chance encounter of the X-chromosome carrying sperm fertilizing the eggs. The chance of the couple getting another daughter is again 50% (so is for the son).
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संबंधित प्रश्न
Differentiate between the following -
Homozygous and Heterozygous
When a cross in 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.
How would you find out whether a given tall garden pea plant is homozygous or heterzygous? Substantiate your answer with the help fo Punnett squares.
What is a monohybrid cross? How did Mendel perform this cross?
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 is the ratio of tall plants to dwarf plants in the F2 generation?
Cross between hybrid and recessive parent:
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?
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.
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.
