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Q.
Heterozygous individual shows intermediate phenotype, find the odd man out for the given condition
NTA AbhyasNTA Abhyas 2020
Solution:
If a heterozygous individual shows intermediate phenotypes, then it is the phenomenon of incomplete dominance.
Stem height in pea plant shows complete dominance. It is a heterozygous condition wherein the allele that is considered as dominant completely masks the effect of the allele that is recessive, only one allele in the genotype is seen in the phenotype.
Flower colour in mirabilis and antirrhinum shows co-dominance. It is a form of inheritance wherein the alleles of a gene pair in a heterozygote are fully expressed. In this case, both the plants show two types of colour in homozygous condition - Red (RR) and White (rr). If we cross these two, then we get a Pink (Rr) coloured flower in the F1 generation. The colour of the flower is due to the blending of red and white, hence it's an example of incomplete dominance.
The starch grain in pea plants shows incomplete dominance. In this, a heterozygous individual combines the two traits of a single gene. It has two alleles B and b that produce large starch grains (BB) and smaller starch grains (bb) in homozygous condition. It was observed that seeds containing BB were round and the bb ones were wrinkled. When they were crossed, the outcome was intermediate-sized (Bb) seeds.