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प्रश्न
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उत्तर
In a dihybrid cross , two pairs of alleles or contrasting characters are considered in parents.
For example, cotyledon colour and seed shape of pea are used as two pairs of alleles.
Suppose, among the two parents, one was true breeding dominant i.e. yellow coloured cotyledons and round seeds, YYRR and the other was a true breeding recessive i.e. green coloured cotyledons and wrinkled seeds, yyrr. On crossing the two parents, F1 generation so obtained had all yellow and round seeds.
On self pollinating, the hybrids - YyRr produced four types of seeds in F2 generation:
(i) Yellow cotyledons and round seeds (YYRR)
(ii) Yellow cotyledons and wrinkled seeds (YYrr)
(iii) Green cotyledons and round seeds (yyRR)
(iv) Green cotyledons and wrinkled seeds (yyrr)
Thus the phenotypic ratio of a dihybrid cross is 9:3:3:1.
APPEARS IN
संबंधित प्रश्न
A homozygous Tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf plant (t) bearing white flowers (r):
(1) Give the Genotype and Phenotype of the F2 generation.
(2) Give the possible combinations of the gametes that can be obtained from the F2 hybrid.
(3) Give the dihybrid ratio and the phenotype of the offsprings of the F2 generation when two plants of the F1 generation above are crossed.
Complete the following sentence with appropriate word:
A character that is suppressed is _________.
Test cross involves
Select the period for Mendel’s hybridization experiments
Identify the statementls that is/are NOT the correct reason/s for Mendel's success in his hybridization experiments.
i. Each factor controlled the single trait and is located on separate chromosomes.
ii. In the pea plant, contrasting characters can be easily recognized.
iii. Mendel carefully recorded the number of plants of each type and expressed his results as ratios.
iv. Mendel performed biochemical assays for identifying the position of 'factors' on chromosome.
In a dihybrid cross AABB x aabb, F2 progeny of AABB, AABb, AaBB and AaBb occurs in the ratio of ______.
Mendel’s Law of independent assortment holds good for genes situated on the ______.
Independent assortment means:
The ratio of 9 : 3 : 3 : 1 is due to:
What is the first step in Mendel's experimental sequence for studying heredity?
