In a Mendel's dihybrid experiment, a homozygous pea plant with round yellow seeds was crossed with a homozygous plant with wrinkled green seeds. F₁ intercross produced 560 F₂ progeny. The number of F₂ progeny having both dominant traits (round and yellow) is ________
Diploid Inheritance Calculation
In Mendel's dihybrid cross, the inheritance of two different traits is studied. The initial cross is between a homozygous plant with dominant traits (Round Yellow seeds, genotype $RRYY$) and a homozygous plant with recessive traits (wrinkled green seeds, genotype $rryy$).
F₁ Generation
All F₁ offspring are heterozygous ($RrYy$) and display the dominant phenotypes (Round and Yellow).
F₂ Generation Phenotypic Ratio
When F₁ plants ($RrYy$) self-cross ($RrYy$ x $RrYy$), the F₂ generation exhibits a specific phenotypic ratio based on independent assortment:
- 9 Dominant, Dominant (Round, Yellow)
- 3 Dominant, Recessive (Round, green)
- 3 Recessive, Dominant (wrinkled, Yellow)
- 1 Recessive, Recessive (wrinkled, green)
The total ratio is $9 + 3 + 3 + 1 = 16$.
Calculating F₂ Progeny Count
The question states that the F₁ intercross produced 560 F₂ progeny. We need to find the number of progeny exhibiting both dominant traits (Round and Yellow).
The proportion of F₂ progeny with both dominant traits is 9 out of 16 ($\frac{9}{16}$).
The expected number of F₂ progeny with both dominant traits is calculated as:
$ \text{Number} = \left(\frac{9}{16}\right) \times \text{Total F₂ Progeny} $ $ \text{Number} = \left(\frac{9}{16}\right) \times 560 $ $ \text{Number} = 9 \times \left(\frac{560}{16}\right) $ $ \text{Number} = 9 \times 35 $ $ \text{Number} = 315 $Therefore, the number of F₂ progeny having both dominant traits (round and yellow) is 315.
Important Questions from Mendelian Inheritance
- Mendel's 'law of segregation' applies to the segregation of __________ during gamete formation.
- Fabry disease in humans is a X-linked disease. The probability (in percentage) for a phenotypically normal father and a carrier mother to have a son with Fabry disease is ________.
The allele associated with albinism in humans is recessive ($c$). The probability that an albino male ($cc$) and a carrier female ($Cc$) will have an offspring with normal skin pigmentation is _________.
(Round off to one decimal place)
- The blood group of the mother is A⁺ and that of the father is AB⁺. Which of the following statements is/are correct?
- Assuming independent assortment and no recombination, the number of different combinations of maternal and paternal chromosomes in gametes of an organism with a diploid number of 12 is ________.
