Match List-I with List-II

Choose the correct answer from the options given below.

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

The correct answer is Option (2) → (A)-(IV), (B)-(III), (C)-(II), (D)-(I)

(A) Multiple alleles → (IV) Population study

• Definition: More than two alternative forms of a gene in a population (though an individual carries only two at a time). Example: ABO blood group system in humans is governed by three alleles – IA, IB, and i.

Why Population study because multiple alleles can be studied only when we analyze gene frequency in populations, not in a single individual.

(B) Mendelian disorder → (III) Pedigree analysis

• Definition: Genetic disorders caused by single genes following Mendel’s inheritance laws. Examples: Sickle cell anemia, Phenylketonuria, Cystic fibrosis. These disorders are often rare; to study how they are inherited across generations, we use pedigree charts (family trees).

(C) Chromosomal disorder → (II) Non-segregation of chromatids during cell division

• Definition: Disorders caused by abnormalities in chromosome number or structure. Examples: Down’s syndrome (trisomy 21), Turner’s syndrome (monosomy X), Klinefelter’s syndrome (XXY). During meiosis, if chromosomes or chromatids fail to separate (nondisjunction), gametes get abnormal chromosome numbers  leading to chromosomal disorders.

(D) Mutation → (I) Variation in DNA

• Definition: Sudden, heritable change in DNA sequence. Examples: Point mutation (sickle cell anemia), frame-shift mutation, insertion, deletion. Mutation directly alters the DNA sequence  causing genetic variability, sometimes leading to diseases.