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प्रश्न
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?
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उत्तर
The following Punnett Square shows a cross between a tall plant with red flowers (TTRR)and a dwarf plant with white flowers (ttrr). All the plants in F1 generation will be tall and will produce red flowers.
When plants of F1 generation are allowed to self-pollinated, phenotype of plants in F2 generation can be shown by following Punnett Square.
In this case, the standard dihybrid ratio 9 : 3 : 3 : 1 which can be shown as follows:
Tall plant red flower = 9
Tall plant white flower = 3
Dwarf plant red flower = 3
Dwarf plant white flower = 1
The standard dihybrid ratio works only when the genes for contrasting characters are on different chromosomes. If characters are on the same chromosome, they may interact with each other. In that situation, the dihybrid ratio would show variation from the standard hybrid ratio.
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संबंधित प्रश्न
Differentiate between the following:
Monohybrid and Dihybrid
A child has blood group O. If the father has blood group A and the mother has blood group B, work out the genotypes of the parents and the possible genotypes of the other offspring.
Explain Mendel’s monohybrid progeny with the help of any one cross.
Mention whether the cross is a monohybrid or dihybrid.
What is a monohybrid cross? How did Mendel perform this cross?
Differentiate Between Monohybrid and Dihybrid cross.
What do you understand by the terms phenotype and genotype?
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?
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?
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.
Mendel used a monohybrid cross to understand how which feature passes from parents to offspring?
Which gametes are produced by each \[Tt\] plant during selfing in F1?
What are the four genotypic outcomes of the cross \[Tt \times Tt\]?
