Chapter 4 Solutions — Principles of Inheritance and Variation

Chapter-end Exercises

1. 1.
   Mention the advantages of selecting pea plant for experiment by Mendel.
2. 2.
   Differentiate between the following —

   • (a) Dominance and Recessive
   • (b) Homozygous and Heterozygous
   • (c) Monohybrid and Dihybrid.
3. 3.
   A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
4. 4.
   Explain the Law of Dominance using a monohybrid cross.
5. 5.
   Define and design a test-cross.
6. 6.
   Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
7. 7.
   When a cross is made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be

   • (a) tall and green.
   • (b) dwarf and green.
8. 8.
   Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F₁ generation for a dihybrid cross?
9. 9.
   Briefly mention the contribution of T.H. Morgan in genetics.
10. 10.
    What is pedigree analysis? Suggest how such an analysis can be useful.
11. 11.
    How is sex determined in human beings?
12. 12.
    A child has blood group O. If the father has blood group A and mother has blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
13. 13.
    Explain the following terms with example

    • (a) Co-dominance
    • (b) Incomplete dominance
14. 14.
    What is point mutation? Give one example.
15. 15.
    Who had proposed the chromosomal theory of the inheritance?
16. 16.
    Mention any two autosomal genetic disorders with their symptoms.