Remark: Linkage is the physical association of genes. Recombination is the generation of non-parental combinations. Low recombination (e.g., 1.3%) indicates tightly linked genes. High recombination (e.g., 37.2%) indicates loosely linked genes.
Match List-I (Genetic Condition) with List-II (Molecular Basis):
List-I
List-II
A. Sickle-cell anaemia (RBC shape)
I. Changes from biconcave disc to elongated sickle-like structure
B. Molecular change in Beta Globin gene
II. Single base substitution from GAG to GUG
C. Amino acid substitution
III. Glutamic acid (Glu) substituted by Valine (Val)
D. Thalassemia
IV. Reduced rate of synthesis of globin chains (α or β)
Choose the correct answer from the options given below:
Remark: In sickle-cell anaemia, RBC shape changes to sickle-like under low oxygen tension. The molecular change is a single base substitution (GAG to GUG). This causes the amino acid substitution of Glutamic acid by Valine. Thalassemia involves a reduced rate of synthesis of globin chains (quantitative problem).
Match List-I (Allele Function) with List-II (Resulting Trait):
List-I
List-II
A. Unmodified (functioning) allele
I. Dominant trait/Original phenotype
B. Modified allele (non-functional enzyme)
II. Recessive trait (if homozygous)
C. Modified allele (less efficient enzyme)
III. Phenotype may be effected, leading to a recessive trait
D. Modified allele (equivalent enzyme)
IV. Same phenotype as the unmodified allele
Choose the correct answer from the options given below:
Remark: The unmodified (functioning) allele represents the original, dominant phenotype. A modified allele producing a non-functional enzyme leads generally to a recessive trait. A less efficient enzyme (C) can also lead to an effected phenotype. If the modified allele produces an equivalent enzyme, the phenotype is the same (IV).
Match List-I (Genetic Phenomenon) with List-II (Example/Associated Trait):
List-I
List-II
A. Polygenic trait
I. Human skin colour/height
B. Pleiotropy
II. Phenylketonuria (Mental retardation and pigmentation loss)
C. Multiple Alleles
III. ABO blood grouping system ($I^A, I^B, i$)
D. X-linked recessive disorder
IV. Colour blindness/Haemophilia
Choose the correct answer from the options given below:
Remark: Human skin colour and height are polygenic traits. Phenylketonuria is a pleiotropic disease resulting in multiple effects like mental retardation. ABO blood groups involve three alleles, demonstrating multiple alleles. Colour blindness and haemophilia are X-linked recessive disorders.
Match List-I (Mutation Type) with List-II (Mechanism/Example):
List-I
List-II
A. Point Mutation
I. Change in a single base pair of DNA (e.g., Sickle-cell anaemia)
B. Chromosomal Aberrations
II. Loss or gain of a segment of DNA
C. Aneuploidy
III. Gain or loss of a chromosome(s)
D. Frame-shift mutations
IV. Deletions and insertions of base pairs of DNA
Choose the correct answer from the options given below:
Remark: Point mutation involves a change in a single base pair. Chromosomal aberrations involve loss or gain of a DNA segment, commonly seen in cancer cells. Aneuploidy is the gain or loss of whole chromosomes due to failure of segregation. Frame-shift mutations result from deletions and insertions of base pairs.
Match List-I (Drosophila Suitability) with List-II (Characteristic):
List-I
List-II
A. Life cycle duration
I. About two weeks
B. Progeny count
II. Large number of progeny flies from a single mating
C. Sex differentiation
III. Male and female are easily distinguishable
D. Maintenance
IV. Grown on simple synthetic medium in the laboratory
Choose the correct answer from the options given below:
Remark: Drosophila completes its life cycle in about two weeks. A single mating produces a large number of progeny. Sexes are clearly differentiated. They are suitable because they can be grown on a simple synthetic medium.
Match List-I (Sickle-Cell Anaemia Basis) with List-II (Molecular Change):
List-I
List-II
A. Type of disease problem
I. Qualitative problem of synthesizing incorrectly functioning globin
B. Codon change (6th position)
II. GAG to GUG
C. Amino acid change (6th position)
III. Glutamic acid substituted by Valine
D. RBC structural change
IV. Biconcave disc changes to elongated sickle-like structure
Choose the correct answer from the options given below:
Remark: Sickle-cell anaemia is a qualitative problem (incorrect globin). The codon changes from GAG to GUG. This substitutes Glutamic acid for Valine. Under low oxygen tension, RBCs change shape to elongated sickle-like structures.
Match List-I (Thalassemia Characteristics) with List-II (Defining Feature):
List-I
List-II
A. Type of disease problem
I. Quantitative problem of synthesizing too few globin molecules
B. $\alpha$ Thalassemia control
II. Two closely linked genes (HBA1 and HBA2) on chromosome 16
C. $\beta$ Thalassemia control
III. Single gene (HBB) on chromosome 11
D. Result of mutation/deletion
IV. Reduced rate of synthesis of $\alpha$ or $\beta$ globin chains
Choose the correct answer from the options given below:
Remark: Thalassemia is a quantitative problem (too few globin molecules). $\alpha$ Thalassemia is controlled by HBA1 and HBA2 on chromosome 16. $\beta$ Thalassemia is controlled by HBB on chromosome 11. The underlying defect leads to a reduced rate of globin chain synthesis.
Match List-I (Sex Determination Mechanism) with List-II (Organism/Gametes):
List-I
List-II
A. Male Heterogamety (XO)
I. Grasshopper: Males produce sperm with X or no X
B. Male Heterogamety (XY)
II. Humans: Males produce sperm with X or Y
C. Female Heterogamety (ZW)
III. Birds: Females produce gametes Z or W
D. Female Homogamety (XX)
IV. Humans: Females produce only X-containing ova
Choose the correct answer from the options given below:
Remark: XO type (Grasshopper) involves males producing X or O gametes. XY type (Humans/Drosophila) involves males producing X or Y gametes. ZW type (Birds) involves females producing Z or W gametes. Human females (XX) produce only X-containing ova.
Match List-I (Mendelian Law/Principle) with List-II (Explanation/Concept):
List-I
List-II
A. Factors occur in pairs
I. Basis of the Law of Dominance and Law of Segregation
B. Alleles do not blend
II. Core concept of the Law of Segregation
C. Characters are controlled by discrete units
III. Factors (now called genes)
D. Independent segregation of two pairs of characters
IV. Law of Independent Assortment
Choose the correct answer from the options given below:
Remark: Factors (genes) occur in pairs, providing the foundation for Mendel's laws. The lack of allele blending is the core basis of the Law of Segregation. Characters are controlled by discrete units called factors. Independent segregation of two pairs of characters is the Law of Independent Assortment.
