Question

33. Explain the inheritance of seed colour and shape of the seed of pea plant Pisumsativum.
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Answer 1

The starch synthesis in pea plants is controlled by a single gene. It has two alleles B and b. BB homozygotes produced large starch grains as compared to that produced by bb homozygotes. After maturation it was observed that BB seeds were round and bb were wrinkled. When they were crossed the resultant progeny were intermediate-sized Bb seeds. The cross involved is

 

B

B

b

Bb

Bb

b

Bb

Bb

Deviation from Mendel's law of dominance: If starch grain size is considered as the phenotype, then from this angle, the alleles show incomplete dominance. Thus, dominance is not an autonomous feature of a gene, it depends on gene product and production of particular phenotype from this product.

Answer 2

Answer:

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The starch synthesis in pea plants is controlled by a single gene. It has two alleles B and b. BB homozygotes produced large starch grains as compared to that produced by bb homozygotes. After maturation it was observed that BB seeds were round and bb were wrinkled. When they were crossed the resultant progeny were intermediate-sized Bb seeds. The cross involved isB b b Bb BbbBbBb

Deviation from Mendel's law of dominance: If starch grain size is considered as the phenotype, then from this angle, the alleles show incomplete dominance. Thus, dominance is not an autonomous feature of a gene, it depends on gene product and production of particular phenotype from this product.