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Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYPrinciples of Inheritance and Variation3 Marks
Question
  1. You are given tall pea plants with yellow seeds whose genotypes are unknown. How would you find the genotype of these plants? Explain with the help of cross.
  2. Identify a, b and c in the table given below:
S. No.
Pattern of inheritance
Monohybrid $F_1$ phenotypic expression
i.
Co-dominance
a
ii.
b
The progeny resembled only one of the parents
iii.
Incomplete dominance
c
✓

Answer

  1. The given plant has to be crossed with a dwarf plant with green seeds.
Tallness and yellow seeds are dominant traits whereas dwarfness and green seeds are recessive traits.

If the progeny consists of tall plants with yellow seeds, the given plant is homozygous. (Cross 1)

If the progeny shows four phenotypes in the ratio of 1 : 1 : 1 : 1, the given plant is heterozygous for both the traits. (Cross 2)

  1.  
  • a - Both the dominant forms of a trait are expressed in the individual.
  • b- Dominance
  • c- The phenotype is intermediate between the two parental forms of the trait.

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