In a monohybrid cross, what is the phenotypic ratio observed in the F2 generation, assuming complete dominance?
For a monohybrid cross (e.g., Tt x Tt), the F2 phenotypic ratio is 3 Dominant : 1 Recessive (e.g., 3 Tall : 1 Dwarf).
Question 112 of 519
📘 CLASS XII
If a pure tall pea plant (TT) is crossed with a pure dwarf pea plant (tt), all the F1 offspring are tall (Tt). This illustrates which of Mendel's laws?
The Law of Dominance states that in a heterozygous condition, the dominant allele (T) expresses itself and masks the effect of the recessive allele (t).
Question 113 of 519
📘 CLASS XII
A test cross involves crossing an individual with an unknown genotype with a parent having which type of genotype?
A test cross is performed by crossing an organism with an unknown genotype with a homozygous recessive parent to determine if the unknown is homozygous dominant or heterozygous.
Question 114 of 519
📘 CLASS XII
In a dihybrid cross involving pea plants for seed shape (Round/Wrinkled) and seed color (Yellow/Green), what is the expected phenotypic ratio in the F2 generation?
The Law of Independent Assortment dictates that the F2 phenotypic ratio of a dihybrid cross is 9 (Double Dominant) : 3 (Dominant/Recessive) : 3 (Recessive/Dominant) : 1 (Double Recessive).
Question 115 of 519
📘 CLASS XII
What is the phenotypic outcome of a cross between a red-flowered snapdragon (RR) and a white-flowered snapdragon (rr) in the F1 generation, if the trait shows incomplete dominance?
In incomplete dominance, the heterozygote (Rr) expresses an intermediate phenotype, resulting in pink flowers.
Question 116 of 519
📘 CLASS XII
Human ABO blood groups are an excellent example of which non-Mendelian inheritance pattern?
The ABO blood group system is governed by three alleles (IA, IB, i), showing Multiple Allelism, and IA, IB show Co-dominance in IAIB genotype.
Question 117 of 519
📘 CLASS XII
Which genotype represents Blood Group AB in humans?
Blood Group AB is the result of co-dominance between the IA and IB alleles.
Question 118 of 519
📘 CLASS XII
If a child has blood group O (ii), and the father has blood group A (IA i), what is the mother's most likely genotype, assuming she is blood group B?
For the child to be blood group O (ii), both parents must contribute the i allele; thus, the mother must be IB i.
Question 119 of 519
📘 CLASS XII
What is the phenotypic ratio in the F2 generation of an incomplete dominance cross (e.g., pink snapdragons × pink snapdragons)?
In incomplete dominance, the genotypic ratio 1:2:1 matches the phenotypic ratio (1 Red : 2 Pink : 1 White).
Question 120 of 519
📘 CLASS XII
Linkage is the exception to which of Mendel's laws?
Linkage occurs when genes are close on the same chromosome and inherited together, violating independent assortment.
