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Q15:
Who had proposed the chromosomal theory of the inheritance?
Solution :
The Chromosomal Theory of Inheritance: Proponents and Theoretical Basis
The Chromosomal Theory of Inheritance was independently proposed by two prominent biologists in the early 20th century. This theory serves as the fundamental bridge between Mendelian genetics and cytological observations.
Step 1: Identifying the Proponents
The theory was proposed by Walter Sutton and Theodor Boveri in the year 1902. Consequently, it is formally known as the Sutton-Boveri Theory.
Step 2: Analytical Core of the Theory
Sutton and Boveri observed that the behavior of chromosomes during meiosis parallels the behavior of Mendel’s factors (genes). The core tenets established by this theory include:
- Pairing: Like genes, chromosomes are found in homologous pairs in diploid cells [Per the Law of Segregation].
- Segregation: During the formation of gametes, members of a chromosome pair segregate into different gametes, ensuring that each gamete contains only one allele for each trait.
- Independent Assortment: Different chromosome pairs migrate to the gametes independently of one another during Anaphase I of meiosis [Per the Law of Independent Assortment].
Step 3: Comparative Analysis
| Characteristic | Mendelian Factor (Gene) | Chromosomal Behavior |
|---|---|---|
| Occurrence | Occur in pairs | Occur in pairs |
| Segregation | Segregate at gametogenesis | Segregate at meiosis |
| Assortment | Independent assortment | Independent assortment |
Visualization of Chromosomal Segregation
Step 4: Theoretical Synthesis
By identifying that chromosomes represent the physical vehicles of heredity, Sutton and Boveri provided the cytological basis for Mendel's laws. This unification of the particulate theory of inheritance and the physical structure of the cell is known as the Sutton-Boveri Chromosomal Theory of Inheritance.
Final Solution: The Chromosomal Theory of Inheritance was proposed by Walter Sutton and Theodor Boveri in 1902.
More Questions from Class 12 Biology Principles of Inheritance and Variation EXERCISES
- Q1: Mention the advantages of selecting pea plant for experiment by Mendel.
- Q1: Mention the advantages of selecting pea plant for experiment by Mendel.
- Q2(a): Differentiate between the following – (a) Dominance and Recessive
- Q2(a): Differentiate between the following – (a) Dominance and Recessive
- Q2(b): Differentiate between the following – (b) Homozygous and Heterozygous
- Q2(b): Differentiate between the following – (b) Homozygous and Heterozygous
- Q2(c): Differentiate between the following – (c) Monohybrid and Dihybrid.
- Q2(c): Differentiate between the following – (c) Monohybrid and Dihybrid.
- Q3: A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
- Q3: A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
- Q4: Explain the Law of Dominance using a monohybrid cross.
- Q4: Explain the Law of Dominance using a monohybrid cross.
- Q5: Define and design a test-cross.
- Q5: Define and design a test-cross.
- Q6: 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.
- Q6: 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.
- Q7(a): When a cross in 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.
- Q7(a): When a cross in 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.
- Q7(b): When a cross in 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 (b) dwarf and green.
- Q7(b): When a cross in 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 (b) dwarf and green.
- Q8: Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in \(F_{1}\) generation for a dibybrid cross?
- Q8: Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in (F_{1}) generation for a dibybrid cross?
- Q9: Briefly mention the contribution of T.H. Morgan in genetics.
- Q9: Briefly mention the contribution of T.H. Morgan in genetics.
- Q10: What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q10: What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q11: How is sex determined in human beings?
- Q11: How is sex determined in human beings?
- Q12: A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
- Q12: A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
- Q13(a): Explain the following terms with example (a) Co-dominance
- Q13(a): Explain the following terms with example (a) Co-dominance
- Q13(b): Explain the following terms with example (b) Incomplete dominance
- Q13(b): Explain the following terms with example (b) Incomplete dominance
- Q14: What is point mutation? Give one example.
- Q14: What is point mutation? Give one example.
- Q15: Who had proposed the chromosomal theory of the inheritance?
- Q16: Mention any two autosomal genetic disorders with their symptoms.
- Q16: Mention any two autosomal genetic disorders with their symptoms.
CBSE Solutions for Class 12 Biology Principles of Inheritance and Variation
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
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